Machinery industry – Page 13 – CNC Machining & Turning, Milling, Metal parts

The development trend of heat flow path

The components of the heat flow path technology show several main development trends.

It’s the miniaturization of components. Miniaturization of the components can realize the first mock exam of small products and multi gate filling of large products. By reducing the nozzle space, more cavity can be arranged on the mold, which can improve the product production and injection machine utilization rate, which is very important for the modern plastic processing industry with “time is money”. Moldmaters, an international famous mold enterprise, has developed nozzles for small parts, including integral heater, needle tip and melt channel, with a volume diameter of less than 9 mm, and gate spacing of only 10 mm, and can be molded into products with a quality of 1-30 G.
It is component standardization. At present, the user requires that the die design and manufacturing cycle is shorter and shorter, and standardizing the hot runner elements is not only conducive to reducing the repetition of design work and reducing the cost of the mold, but also for the replacement and maintenance of vulnerable parts. Nozzles, stem and diverter plates from companies such as Husky, Presto and moldmaters are standard, which facilitate rapid replacement and delivery of moulds. Now, the mold can be delivered only four weeks abroad.
It is the reliability of design. Nowadays, the design of hot runner plate and the research and development of pressure distribution, temperature distribution and sealing of the heat nozzle joint are paid great attention to by the major mold companies at home and abroad. The development and utilization of the injection mold for laminated hot runner are also hot spots. The number of cavity can be increased effectively by the stack mold, but the requirement of the injection machine die closing force only needs to increase by 10% – 15%. The stack hot runner mold has been industrialized in some developed countries abroad.
It is the accuracy of temperature control system. In the mold molding of hot runner, developing more precise temperature control device and controlling the temperature of molten resin in hot runner plate and gate are effective measures to prevent resin from overheating degradation and product performance reduction.

The wide application of heat runner technology is a great change of plastic mold. In the aspect of injection molding, it has many incomparable advantages. With the technology becoming more mature and the manufacturing cost is reduced, the heat flow path technology will show more and more great advantages. In recent years, the world famous hot runner technology suppliers have entered the Chinese market in various ways, which shows the huge development potential of the hot runner mould Market in China.

During the forming process of hot runner, the temperature of plastic melt is controlled accurately in the runner system. Plastic can flow into each cavity in a more uniform and uniform state, and the result is the parts of the same quality. The quality of gate of hot runner is good, the residual stress is low after demoulding and the deformation of parts is small. So many high quality products in the market are produced by hot runner die. For example, many plastic parts in the familiar Motorola mobile phone, HP printer and Dell notebook are made by hot runner die.

Eliminating the subsequent processes is conducive to production automation.

The finished product is finished after the hot runner mold is formed. There is no need to trim the gate and recycle the cold runner. It is conducive to production automation. Many foreign manufacturers combine heat flow path with automation to greatly improve production efficiency.

Chip removal method for deep hole machining of die

Twist drill can be used to drill holes with small depth. In order to remove chips smoothly, iron chips should be straight out into thin strips and bring out small fragments. At the same time, the coolant is easy to enter. The grinding method of drill bit can be the grinding method created by Ni Zhifu with three points and seven edges (called group drilling in order not to highlight individuals in the Cultural Revolution)

Increase the angle of the drill edge to 130-140 degrees to increase the chip thickness and change the direction of chip discharge (the direction of chip discharge is perpendicular to the edge)
Grinding the transverse edge to reduce the axial cutting tool, at the same time, the cutting edge near the core produces a break angle to facilitate chip separation.
If the drilling diameter is large, the chip separation groove can be ground on one side of the cutting edge to balance the cutting force of the two cutting edges. If the diameter is large, the chip separation groove can be grinded at the two cutting edges.
Reverse 1 mm 45 degrees to the outside corner of the edge to reduce wear and improve finish.

5。 The drilling speed is slightly lower, and the feed rate should be larger, so that the chip thickness is discharged in a strip shape.

The nozzle of the coolant should face the hole inward to facilitate the coolant to enter the cutting area,

Mold deep hole processing manufacturers found that when the hole diameter ratio is more than 8 times and the batch is large, it is best to drill on a special deep hole drilling machine, which has high efficiency. It has tried to produce lathe spindle diameter of 32 and length of about 850 mm, and 45 steel only takes 13 minutes.

Deep hole drilling can be divided into external chip removal and internal chip removal. The smaller diameter drill pipe adopts the external chip removal method, because the drill pipe is too small. There is enough space for chip removal in the inner hole of the drill pipe for the larger diameter hole. High pressure oil is pressed between the hole wall and the drill pipe to discharge the chips and heat from the rod. The drill bit is specially made and generally uses cemented carbide, which is divided into two parts: the direction and the cutting edge, The chip edge is ground into a trapezoid to separate chips. The height and width of the chip breaking groove depend on the material and feed rate of the workpiece. It is better to ensure that the chip shape is compact and small in shape of C or tile.

报错笔记

Computer gong machining – crankshaft

In internal combustion engine, the function of crankshaft is to convert reciprocating motion of piston into rotary motion. This means severe acceleration and deceleration, accompanied by high bending deformation, high torque and vibration impact, results in very high and variable stresses.

Such extreme stress requires careful design and calculation, selection of suitable materials and batch production process. These stresses are mainly located at the fillet radius between the bearing journal and the balance weight plate as well as on the oil hole, so it is necessary to pay special attention to the fine fabrication of these spaces.

In today’s market, automobile manufacturers are required to provide smaller engines while meeting higher power and speed requirements, which further increases the load and stress of the crankshaft. As a result, manufacturers are constantly looking for higher strength materials for these parts, usually including high alloy metals.

Ductile iron is the standard material for lower load engines (mainly gasoline engines), while high-power engines (including most diesel engines) use more expensive alloy steel forgings. The steels used for crankshafts are generally subjected to various heat treatments, such as quenching and tempering. In some special high-end use areas (including racing cars), crankshafts may be made directly from round steel.

At present, the requirement of large-scale precision machining for crankshaft is the most strict. Crankshaft manufacturing line has also become the largest consumer of cemented carbide in the whole process of automobile production.

A simple method of finishing both ends and Journal of crankshaft is turning on a traditional lathe or turning center. This clearly requires sufficient space from the handle to the finished journal appearance. The advantages of this approach include the ability to apply standardized machine tools, tool heads and blades to achieve high flexibility and low cost.

With the ability of turning and turning, a special machine tool can finish the Journal on the crankshaft rotation center. The blades used for rough and fine manufacturing can be installed on the same cutter head at the same time. High speed computer gongs can be used to make a special shape in one complete cutting stroke. Other benefits include repeated positioning accuracy, good finish appearance quality, smaller tolerance, longer tool head life, higher machine tool utilization due to reduced tool change times, and shorter finishing time. The disadvantage of turning and drawing fine production is that the cost of special machine tool and cutter head is high, and a large number of blades are needed. A more professional way of turning is to use multi tooth turning blades to achieve cost reduction efforts conducive to scrap iron control and not to use broaching action.

No matter what method is adopted, the overall goal of crankshaft finishing includes scrap iron control, prolonging tool head life, shortening finishing beat and improving product quality. Crankshafts are usually manufactured in large quantities on a production line consisting of several special machine tools. However, the one-piece refinement method can also be used in some special turnkey projects, such as racing engine crankshaft and marine diesel crankshaft.

External and internal milling represents another approach, especially the finishing of the connecting rod neck. If the balance weight has large allowance to be removed, the milling cutter head with cutter block with blade is an attractive choice. Sandvik has more than 40 years of experience with these uses. Oil hole drilling and milling are the most consumed technologies of cemented carbide in crankshaft manufacturing.

In the crankshaft oil hole, the hole depth is usually 20 times of the diameter, so it is very difficult to finish the task. The most widely used tools include gun drill and carbide twist drill lubricated by oil mist. High quality precision fabrication is also essential because of the possibility of major stresses around the borehole.

Stefan Knecht, global solutions manager of the crankshaft capability center in Dusseldorf, Germany, said: “although there are hundreds of cutting tool head manufacturers in the world, only six have the ability to supply cutting heads for crankshaft precision manufacturing, and even fewer companies really promote the technology development of the industry. Sandvik is one of the few

The center works with OEMs and machine tool manufacturers around the world, with projects in about 20 countries. Emerging markets are expanding in this area, especially in China, where the centre recently opened a new branch.

Crankshaft precision manufacturing is one of the most demanding industries in automobile production. The key requirements of all finishing methods are the same, including scrap iron control, prolonging tool head life, shortening finishing beat and improving product quality.

Computer gong processing – knife alignment

The feed machining route of CNC lathe refers to the path that the tool moves from the point of alignment (or fixed origin of machine tool) until it returns to the point and ends the machining procedure, including the path of cutting and the path of cutting tool cutting and cutting out.

The feed route of finishing is basically carried out in the order of the outline of parts. Therefore, the key to determine the feed route is to determine the feed route of rough machining and empty stroke.

In the NC lathe processing, the determination of the processing route should follow the following principles.

① The accuracy and surface roughness of the workpiece to be processed shall be guaranteed.

② The shortest processing route, reducing the time of empty travel and improving the processing efficiency.

③ The work of numerical calculation and the processing procedure are simplified as much as possible.

④ For some reuse programs, subroutines should be used.

CNC advantages and disadvantages CNC machining has the following advantages:

① A large number of tooling is reduced, and complex tooling is not needed for parts with complex shapes. To change the shape and size of parts, only the part processing procedure needs to be modified, which is suitable for the development and modification of new products.

② The machining quality is stable, the processing precision is high, the repetition precision is high, which is suitable for the machining requirements of the aircraft.

③ The production efficiency is high under the condition of multi variety and small batch production, which can reduce the time of production preparation, machine tool adjustment and process inspection, and reduce the cutting time due to the use of the best cutting quantity.

④ The complex profile which can be processed by conventional methods is difficult to process, and even some parts which cannot be observed can be processed.

The disadvantage of NC machining is that the machine tool equipment is expensive, and it requires the maintenance personnel to have a high level.

Turn milling compound machining

According to the accuracy requirements, that is, the dimensional accuracy, positioning accuracy and surface roughness of the workpiece, the control accuracy of the CNC lathe is selected. Reliability is the guarantee to improve product quality and production efficiency. The reliability of CNC machine tool means that the machine tool can run stably for a long time without failure when it performs its functions under specified conditions. That is, the average time between failures is long, even if there is a fault, it can be recovered in a short time and put into use again. Select the machine tools with reasonable structure, excellent manufacturing and mass production. Generally, the more users, the higher the reliability of CNC system.

Turning center 2. Machine tool accessories and tool selection

Machine tool accessories, spare parts and their supply capacity, cutting tools are very important for CNC lathes and turning centers that have been put into production. When selecting machine tools, the matching of tools and accessories should be carefully considered.

Pay attention to the identity of control system

Manufacturers generally choose the same manufacturer’s products, at least the same manufacturer’s control system, which brings great convenience to the maintenance work. Teaching units, due to the need for students to be knowledgeable, choose different systems, equipped with a variety of simulation software is a wise choice.

Select according to the performance price ratio

Do not idle and waste functions and accuracy, and do not choose functions irrelevant to your own needs.

Protection of machine tool

If necessary, the machine tool can be equipped with fully enclosed or semi enclosed protective devices and automatic chip removal devices.

When selecting CNC lathe and turning center, the above principles should be considered comprehensively.

Determine the process requirements of typical parts and the batch of processed workpieces. The function of NC lathe is to prepare well in the early stage, and the precondition of reasonable selection of CNC lathe meets the process requirements of typical parts.

The process requirements of typical parts are mainly the structural size, processing range and precision requirements of the parts. According to the accuracy requirements, that is, the dimensional accuracy, positioning accuracy and surface roughness of the workpiece, the control accuracy of the CNC lathe is selected. Reliability is the guarantee to improve product quality and production efficiency. The reliability of CNC machine tool means that the machine tool can run stably for a long time without failure when it performs its functions under specified conditions. That is, the average time between failures is long, even if there is a fault, it can be recovered in a short time and put into use again. Select the machine tools with reasonable structure, excellent manufacturing and mass production. Generally, the more users, the higher the reliability of CNC system.

Turning center 2. Machine tool accessories and tool selection

Pay attention to the identity of control system

Select according to the performance price ratio

Do not idle and waste functions and accuracy, and do not choose functions irrelevant to your own needs.

Protection of machine tool

If necessary, the machine tool can be equipped with fully enclosed or semi enclosed protective devices and automatic chip removal devices.

When selecting CNC lathe and turning center, the above principles should be considered comprehensively.

Firstly, determine the process requirements of parts and the batch of processed workpieces, draw up the functions that the CNC lathe should have, prepare well in the early stage, and reasonably select the preconditions of CNC lathe to meet the process requirements of typical parts. The process requirements of typical parts mainly include the structural dimension, processing range and precision requirements of the parts. According to the accuracy requirements, that is, the dimensional accuracy, positioning accuracy and surface roughness of the workpiece, the control accuracy of the CNC lathe is selected. Reliability is the guarantee to improve product quality and production efficiency. The reliability of CNC machine tool means that the machine tool can run stably for a long time without failure when it performs its functions under specified conditions. That is, the average time between failures is long, even if there is a fault, it can be recovered in a short time and put into use again. Select the machine tools with reasonable structure, excellent manufacturing and mass production. Generally, the more users, the higher the reliability of CNC system. General import system has Japan Sanling, farnac, Germany’s Siemens, domestic Guangshu, Kandi, new generation more commonly used

CNC lathe processing materials are: 304, 316 stainless steel, carbon steel, copper, aluminum, alloy, plastic, POM, etc. However, the products of different materials need to choose different quality cutting tools to ensure the accuracy required by each product. Composite machining is one of the most popular machining technologies in the field of mechanical processing. It is an advanced manufacturing technology. Compound machining is to realize several different processing technologies on one machine tool. Compound machining is the most widely used and the most difficult one is turn milling compound machining. Turning milling compound machining center is equivalent to the compound of a CNC lathe and a machining center.

At present, most of the turn milling compound machining is completed on the turning center, while the general turning center only changes the ordinary turret turret of CNC lathe into the turret turret with power tool, and the spindle adds the c-axis function. Due to the limitation of turret structure and dimension, the power of power head is small, and the speed is not high

CNC engraving and milling machine

The spindle speed of engraving and milling machine is high, which is suitable for processing small cutting tools, and its torque is relatively small. It focuses on the “carving” function, such as wood (wood carving machine for special processing of wood), dual color board, acrylic plate and other plates with low hardness. It is not suitable for CNC processing of large workpieces with strong cutting. At present, most of the products marked with engraving machine banner are mainly for processing handicrafts with low cost, Due to the low precision, it is not suitable for mold development, but there are also exceptions, such as wafer engraving machine. Advantages: it can carry out relatively small processing and high machining accuracy. High speed machining is possible for soft metals; disadvantage: heavy cutting is not possible due to poor rigidity.

Troubleshooting of CNC engraving and milling machine

（1） . usage environment

CNC engraving and milling machine is a high-tech mechatronics equipment, which has certain requirements for the working environment.

The voltage is required to be stable and avoid large fluctuation. It is better to use voltage regulator.
The machine should not work in strong acid and alkali environment for a long time.
Avoid strong electricity, strong magnetism and other equipment that seriously affect the signal transmission of engraving and milling machine. Such as: welding machine, launch tower, etc.
Use three core power supply to ensure good grounding of engraving and milling machine and reduce interference.

（2） . processing problems

Operators

The proficiency and sense of responsibility of operators also have a great impact on the machining accuracy.

Wear and tear of the machine

CNC engraving and milling machine wear is inevitable in the process of use, with the passage of time, machine wear will reduce the accuracy of the machine.

Rationality of processing technology

In addition to CNC engraving and milling machine to ensure the machining accuracy, reasonable processing technology is also very important. CNC machining in order to ensure the accuracy of processing, please pay attention to the rationality of the processing technology.

Tool use

The machining accuracy is affected by the manufacturing process and accuracy of the tool itself. Therefore, please select the suitable tool for machining.

（3） . maintenance and maintenance

CNC engraving and milling machine is mostly used in processing business, which produces a lot of powder foam and dust. During use, attention should be paid to keep the screw rod, polished rod and other parts clean and lubricated, timely clean up the dust and add oil to the transmission parts; the operator should clean and add oil in time, and it is strictly forbidden to plug and plug with electricity.

（4） . software usage problems

There are many engraving and milling software for CNC engraving and milling machine. In order to meet your engraving and milling requirements, please select the correct operation software. At present, most enterprises in CNC cutting machine tool industry rely on reducing the product price to obtain the market. The result is that the product price is low, the added value is low, the profit is low, and the enterprise does not have enough funds for sustainable development. Low price competition, imitation and OEM production are limited to a certain historical stage. With the development of the industry and the upgrading of competition, it is the best choice for enterprises to improve the technical content of products, have independent patents and designs, and pay attention to brand building and marketing.

The decorative development trend of CNC machine tools can be seen. CNC cutting machine tools emphasize more on mechanical properties, simple operation, economic price, stable processing accuracy and so on. Nowadays, with the increasing demand for popularization and batch processing of metal materials, CNC cutting machine tools should not only meet the above functions, but also have the applicability of multiple cutting methods. At present, CNC cutting machine tools can be divided into flame cutting and plasma cutting. In recent years, with the continuous improvement of downstream industry demand, the CNC machine tool accessories put forward greater demand and higher requirements.

It is understood that the next few years will be the high-speed development and shock period of CNC machine tool industry. The direct consequence of this high-speed shock is that the polarization trend in the current decoration CNC machine tool brand camp is more obvious and expanded. CNC machining is expected to be able to survive in the market in the next few years, the number of CNC machine tool enterprises will drop sharply. However, the high-speed vibration of CNC machine tool industry will also bring great opportunities to make the market operation more rational and standardized.

Surface roughness of computer gongs

Because the spindle speed and range of CNC machine tools are far higher than ordinary machine tools, and the output power of the spindle is large, compared with the traditional processing methods, higher requirements are put forward for the CNC machining tools, including high precision, high strength, good rigidity, high durability, and the size stability, convenient installation and adjustment, and the characteristics of the spindle drive system of CNC machine tools. This requires that the structure of the tool is reasonable, the geometric parameters are standardized and serialized. NC tool is one of the preconditions to improve the machining efficiency. Its selection depends on the geometry of the parts to be processed, the material state, the fixture and the rigidity of the selected tool. The following aspects should be considered:

(1) The cutting tool is selected according to the cutting performance of the part material. If turning or milling high strength steel, titanium alloy, stainless steel parts, it is recommended to select indexable carbide tool with good wear resistance.

(2) Select the tool according to the hardware parts processing stage. That is to say, in the rough machining stage, the cutting tool with better rigidity and lower precision should be selected; in the semi finishing and finishing stage, the machining accuracy and product quality of the parts should be guaranteed; the tools with high durability and high precision should be selected; the precision of the tools used in the rough machining stage is the lowest, while that in the finishing stage is the highest. If the same tool is selected for rough machining and finish machining, it is recommended to select the tool eliminated from finish machining during rough machining, because most of the tool wear out of finishing machining is slight wear on the edge, and coating wear and polishing. Continuous use will affect the quality of finish machining, but the impact on rough machining is small.

(3) According to the characteristics of NC lathe processing area, the tool and geometric parameters are selected. The tool with large diameter and small ratio of length to diameter should be selected if the structure of the part is allowed; the end edge of the cross center milling cutter for cutting thin-walled and ultra-thin-wall parts should have enough centripetal angle to reduce the cutting force of the cutter and cutting parts. When processing aluminum, copper and other soft material parts, the end mill with larger front angle should be selected, and the number of teeth should not exceed 4.

When selecting the tool, the size of the tool should be compatible with the surface size of the workpiece to be processed. In production, end milling cutter is often used for peripheral contour processing of plane parts; when milling plane, carbide blade milling cutter should be selected; when machining boss and groove, high-speed steel end milling cutter should be selected; when hardware processing blank surface or rough machining hole, corn milling cutter with cemented carbide blade can be selected; Ball end milling cutter, ring milling cutter, conical milling cutter and disc milling cutter are often used in the machining of solid surface and variable bevel profile.

In the process of free-form surface machining, because the cutting speed of the ball end cutter is zero, in order to ensure the NC machining accuracy, the cutting row spacing is generally very small, so ball end milling cutter is suitable for surface finishing. The end milling cutter is far better than the ball end milling cutter in both surface processing quality and processing efficiency. Therefore, under the premise of ensuring that the parts can not be cut, the end milling cutter should be selected as far as possible when rough machining and semi finishing surface machining. In addition, the durability and accuracy of cutting tools are closely related to the price of cutting tools. It must be noted that in most cases, although the selection of good tools increases the cost of cutting tools, the improvement of processing quality and efficiency brought about by this can greatly reduce the whole processing cost.

In the machining center, all the tools are pre installed in the tool library, and the corresponding tool change action is carried out through the tool selection and tool change instructions of the NC program. It is necessary to select the corresponding standard tool holder suitable for the machine tool system specification, so that the tool for NC machining can be quickly and accurately installed on the machine tool spindle or returned to the tool magazine. The programmer should be able to understand the structure size, adjustment method and adjustment range of the tool holder used by the machine tool, so as to ensure that the radial and axial dimensions of the tool can be determined and the arrangement order of the tool can be arranged reasonably.

The surface geometric characteristics of NC machining include surface roughness, surface waviness and surface texture. Surface roughness is the basic unit of geometric characteristics of machined surface. When machining workpiece surface with metal cutting tools, surface roughness is mainly affected by geometric factors, physical factors and NC machining process factors.

(1) Geometric factors

From the geometric point of view, the shape and geometric angle of the tool, especially the radius of the tool tip arc, the main deflection angle, the secondary deflection angle and the feed rate in cutting parameters have a great influence on the surface roughness.

(2) Physical factors

Considering the physical essence of the cutting process, the metal material plastic deformation is caused by the corner of the cutting edge and the extrusion and friction behind the tool, which seriously worsens the surface roughness. When the plastic material is processed by numerical control lathe to form strip chip, it is easy to form chip accretion with high hardness on the rake face. It can replace the rake face and cutting edge for cutting, so that the geometric angle of the cutter and the back feed can be changed. The contour of the chip accretion is very irregular, so that the depth and width of the workpiece surface are constantly changing. In CNC machining, some chips are embedded in the workpiece surface, which increases the surface roughness. The vibration during cutting increases the surface roughness parameters.

(3) Technological factors

From the perspective of technology, the influence on the surface roughness of metal parts is mainly related to cutting tools, workpiece materials and CNC processing conditions.

Accuracy of slender rod like tools

Accuracy analysis of machining slender rod-shaped tools by CNC machine tools: the improvement of the accuracy of rod-shaped tools has always been a difficulty in tool manufacturing. The main reason is that the effective part of the tool is too long and the cutting edge of the tool is too far from the clamping part during manufacturing. Because the cutting edge is too far away from the clamping part, and the chuck has certain clamping accuracy (generally 0.002 ~ 0.005mm), the radial circular runout at the cutting edge of the cutter may have reached 0.005mm ~ 0.01mm (or even greater) before grinding. Due to the large grinding force and the large elastic deformation of the tool, there will be many problems in the machining process, such as the asymmetry of the tool groove, the size of the tool’s outer circle, the parameters of the cutting edge and the shape error are not up to the requirements, and even the tool is broken in serious cases. The following is a simple analysis of the accuracy of the tool when machining slender rod-shaped tools with CNC machine tools.

1、 The influence of machine tools on tool accuracy. The influence of machine tool accuracy on tool accuracy the accuracy of machine tool is the key to determine the accuracy of any tool, and the slender rod-shaped tool is no exception. The support block equipped with this machine tool is mainly used for CNC machining slender rod-shaped tools. Its position can be adjusted in the horizontal and longitudinal direction, and can be positioned according to the actual situation. If the position of the support block in the transverse direction (i.e. the axial direction of the tool) is not reasonable, the qualified slender rod-shaped tool cannot be machined. If the support block is too low, the support force to the tool is not enough, which will cause the tool groove to form an inverted cone in the axial direction; if the support block is too high, the support block will force the tool against the tool, which will lead to the tool groove forming a cone along the axis. Therefore, the accurate positioning of the support block is also very important to the accuracy of the tool.

2、 The influence of CNC grinding wheel on tool accuracy. All parameters of the cutter are determined by the relative motion between the grinding wheel and the cutter. Therefore, the diameter of the grinding wheel, the angle of the grinding wheel directly participating in the cutting, the flange length of the grinding wheel shaft, the wear of the grinding wheel and the grain size of the grinding wheel all affect the accuracy of the cutter. The accuracy of grinding wheel angle measurement or input may cause: the width of cutting edge belt does not conform to the requirements; the angle of stepped cutter’s step surface does not meet the requirements; the position or angle of tool back angle has error; the groove angle of chip removal groove has error.

3、 The cooling effect of the coolant on the grinding area will directly affect the accuracy of the cutting tool when machining hardware parts. The selection of coolant with good performance and proper cooling pressure is conducive to the coolant entering the grinding zone, which can take away the cutting heat and chips in time, and effectively reduce the surface roughness of the tool.

CNC punch press is a kind of equipment which can automatically blanking sheet metal according to the NC machining program. The ideal processing program should not only ensure that the hardware parts can be processed to meet the design requirements of qualified parts, but also can make the CNC punch get reasonable application and give full play to its performance.

With the development of stamping equipment, more and more numerical control blanking technology is used. Through the research and analysis of the process characteristics of numerical control processing, this paper puts forward some matters that should be paid attention to in the program design of numerical control punching, and illustrates the correct method to complete each work with corresponding examples. The author of the article has rich practical experience, because some articles have strong practicability.

When designing numerical control program, whether it is manual programming or automatic programming, it is necessary to analyze the processing technology of hardware parts before programming, and then work out the processing scheme, formulate the correct and reasonable processing process, and select the appropriate mold and processing speed. In the design of numerical control program, hardware processing plant should pay more attention to some process methods of program design. If some process details are ignored, sometimes even if the processing program is correct, due to the unreasonable process method of the program, it is impossible to process qualified parts. What’s more, it will cause alarm and damage to the machine tool.

Influence of cutting tools on accuracy

However, these standards impose various restrictions on milling cutters and inserts, which stipulate the shape and thickness of the blades, the inscribed circle of the cutting blades, the dimensions of the blade holder and wedge clamping parts, and the size of the cutter body. Due to the limited design range of blade material, edge and chip breaking groove, the standard tool suppliers and production are limited by the machining function.

However, today, the concept of milling cutter tends to be flexible. Computer gong machining provides tool developers with the freedom to adopt new tool and blade design. These designs can be optimized. With the new tool concept, CNC machining can better solve the problems of machining safety, accuracy, surface quality, metal removal rate, tool overhang, high-speed cutting, and the ability of different cutting paths Question.

Today’s milling tools are constantly optimized to meet the needs of modern production, machine tools and data, and are widely accepted by all industries. The new cutting tool can remove metal several times faster, with smaller cutting force and better orientation. Its typical runout is only a fraction of that of the old standard tool. Therefore, the machining tolerance can always be controlled in a smaller range, and the cutting edge loss is also smaller and more ideal. The axial and radial runout is very small, which means that the cutting edge accuracy is improved, so the surface quality of the workpiece is better, the tolerance is smaller, the tool life is longer, and the cutting load is more evenly distributed, so as to improve the cutting speed and reduce the noise, vibration and loss.

The use of tools also helps to increase spindle speed, high speed feed and hard part milling, and extends the opportunities for dry cutting. The design of these tools is more concise, and the amount of work required for adjustment and maintenance is very small. The cutter body is rigid and accurate in size. It is made of pre hardened steel to ensure that the blade is accurately and firmly installed on the milling cutter body, and the appropriate tooth pitch can be selected according to different application.

The new milling tools use the blade material and groove type developed for specific data or process. The functions and achievements of the new milling cutters equipped with these blades are far better than those of ISO or ans standard tools and inserts. Compared with most standard blades, modern new blades and tools can provide larger positive rake angle and more complex groove shape, thus reducing cutting force and forming synergistic effect of faster and more stable metal removal.

Strengthen the concept of die precision

Die is a precision forming tool used for batch forming and stamping. Mold precision includes the accuracy of parts obtained in processing and the quality awareness of ensuring product accuracy during production. However, the mold precision generally refers to the accuracy of working parts of mold.

① The concept of precision in mold processing refers to the degree of conformity between the actual geometric parameters and the designed geometric parameters after the mold parts are processed and assembled.

② The concept of precision in die and mould production refers to the various thinking modes and quality consciousness formed gradually by the employees in the production practice to guide their production behavior. It is a kind of quality consciousness that the enterprise staff and workers always implement the quality consciousness of grasping the product precision in their behaviors.

The precision of mould includes four aspects: dimension precision, shape precision, position precision and surface precision. Due to the working time of the mold, the upper die and the lower die are two parts, so the position accuracy between the upper and lower dies is the most important among the four kinds of precision.

When the machining precision is very high, the mold is often surplus but force is insufficient. The precision of the die is about 1.0 ~ 0.01 mm, which is much higher than that of the former one. However, such as the engine components, but the accuracy is required to be less than one thousandth of a millimeter, or even smaller. Therefore, it is impossible to completely replace cutting with die.

Mold now its own smoothness, roughness has been a great leap forward. However, the mold itself is also made by machine tools. If the accuracy of the machine tool used to manufacture the mold itself can not pass the standard, the precision of the products produced must not be high.

Computer gong processing – rough, smooth knife

Opening: under the maximum load of machine tool, the most cases should choose the largest knife as possible, the maximum feed amount and the fastest feed as possible. In the same case, the feed is inversely proportional to the feed quantity. Generally, the load of machine tool is not a problem. The principle of selecting tool is mainly considered whether the two-dimensional angle and three-dimensional arc of the product are too small. After selecting the tool, the length of the tool is determined. The principle is that the length of the tool is greater than the processing depth. If the large workpiece is involved, the interference of the chuck should be considered.

Smooth knife: the purpose of the smooth knife is to meet the machining requirements of the surface finish of the workpiece and reserve appropriate allowance. Similarly, the light knife is selected as large as possible, and the time is as fast as possible, because the fine knife takes a long time, and the most suitable feed and feed are used. The larger the transverse feed is, the faster the surface feed is, the surface feed quantity is related to the finish after processing, the feeding size is related to the surface shape. In the case of no damage to the surface, the minimum allowance, the maximum knife, the fastest speed and proper feed are reserved.

2、 Clamping method:

All clamps are horizontal, vertical and short.
Vice Clamp: the height of clamping shall not be less than 10 mm. The height of clamping and machining height must be specified when machining workpiece. The machining height shall be about 5mm higher than the plane of the vise, so as to ensure the firmness and avoid damaging the vise. This kind of clamp is a general clamp, and the height of the clamping is also related to the size of the workpiece. The larger the workpiece, the higher the clamping height will increase accordingly.
Clamp: the clamp is coded on the workbench, and the workpiece is locked on the plywood with screws. This clamp is suitable for the workpiece with insufficient clamping height and large processing force. Generally, medium and large workpieces have good effect.
Iron clamp: when the workpiece is large and the clamping height is not enough, and it is not allowed to lock the thread at the bottom, the clamp shall be installed with code iron. This kind of clamp needs to be installed twice. The four corners shall be coded first, other parts shall be processed, then four sides shall be coded to process the four corners. When installing the clamp twice, do not let the workpiece loose, code and then loosen. You can also code both sides first and process the other side.
Clamping of tools: the diameter is more than 10 mm, the length of clamping is not less than 30mm; the diameter is less than 10 mm, and the clamping length is not less than 20mm. The clamping of the tool shall be firm, and the tool shall be strictly prevented from collision and direct insertion into the workpiece.

3、 Classification and application range of tools:

By material:

White steel knife: easy to wear, used for copper and small steel material to open coarse.

Tungsten steel knife: used for angle cleaning (especially steel material) and light knife.

Alloy knife: similar to tungsten steel knife.

Purple knife; used for high speed cutting, not easy to wear.

According to the cutting head:

Flat bottom knife: used for flat and straight side, clear plane angle.

Ball knife: used for various surface light, light knife.

Nose knife (unilateral, bilateral and five sides): used for steel material opening (r0.8, r0.3, r0.5, r0.4).

Rough leather knife: used for opening and paying attention to the method of remaining the allowance (0.3).

According to the knife rod:

Straight pole knife: straight pole knife is suitable for various occasions.

Inclined pole knife: but not applicable to straight body surface and face with slope less than the bar slope.

According to the blade:

The more the number of blades, the better the effect is, but the more work is done, the corresponding adjustment of speed and feed is, and the number of blades has long life.

Difference between ball knife and flying knife light knife:

Ball knife: concave ruler is smaller than the ball ruler, and when the plane ruler is less than ball R, the light can not be reached (the bottom angle can not be cleared).

Flying knife: the advantage is to clear the bottom corner. Comparison of the same parameters: v = R * ω has a lot of speed (flying knife), the things out of the force are bright, and the flying knives are used for equal height shape, sometimes the flying knife does not need medium light. The disadvantage is that the concave size and plane ruler are less than the diameter of the flying knife.

4、 CNC works with EDM and copper company:

What circumstances need to be made of copper:

If the knife is completely down, it is necessary to be a copper male. In a copper male, there is still something that cannot be lowered. The shape is protruding and needs to be divided again.

The knife can go down, but the knife that is easy to break also needs to be made of copper, which depends on the actual situation.

The products with spark pattern are required to be made of copper.

Copper can not be made, the bone position is too thin and too high, vulnerable and easy to deformation, deformation and spark deformation in processing, so insert is required.

The surface of the East and West (especially the surface will be smooth and even) can overcome many problems in the gong and many problems in the drawing.

If the precise shape or surplus is required, the coarse copper male must be made.

Copper company’s practice:

Select the surface to be made of copper, fill the surface to be repaired, or extend the extended surface to ensure that all edges of copper male are larger than the surface to be punched, and the surface of other products will not be damaged. Unnecessary plane angle (deeper glue position is at the intersection of plane angle) shall be removed to form regular shape; find out the maximum shape of copper male, and then project it to the supporting surface with one side boundary; determine the size of reference frame , cut off the supporting surface, and the copper common drawing is basically completed; material preparation: length * width * height, length and width ≥ ymax and xmax are the actual copper material length and width of the reference frame must be larger than the reference frame on the drawing. The theoretical dimension of the high or equal to copper male + the height of the reference frame + the height of the clamp.

5、 Drawing sizing:

Under the condition of no ready-made processing surface, the plane is divided into four sides, the center is to the origin, the top face is zero, and the top surface is not normally (for copper male) to leave a margin of 0.1, that is, when the number of collisions is 0 (z), the figure is lower than 0.1.
When there are ready-made machining surfaces, make the ready-made face 0 (z) on the drawing, and divide the plane energy into the middle. Otherwise, if the ready-made edge impact number (one side) processing surface is used, the actual height, width, length and drawing difference shall be checked, and the actual material shall be used to program. Generally, the dimensions on the drawing are processed first and then the shape on the drawing is processed