November 2020 – Page 6 – 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.

CNC computer gongs thread milling method

CNC computer gong processing needs to be proficient in horizontal processing, and large gantry (moving beam, top beam) processing. Must have good fixture foundation and measurement technology level. The difficulty of fixture analysis is that it can only be qualitative and difficult to quantify. The operation also pays attention to the handle.

In the CNC computer gongs processing process, there is a method called thread milling method, which specifically refers to it? Thread milling is to use thread milling tool, machining center three axis linkage, namely x, Y axis arc interpolation, Z axis linear feed milling method.

Thread milling is mainly used for machining large hole thread and thread hole of difficult to machine material. It has the following characteristics:

(1) high speed, high efficiency and high precision. The material is generally cemented carbide material, and the cutting speed is fast. The manufacturing precision of cutting tool is high, so the precision of thread milling is high.

(2) milling tools are widely used. As long as the pitch is the same, whether it is * * thread or right-hand thread, one tool can be used, which is conducive to reducing the cost of the tool.

(3) milling is easy to chip removal and cooling. Compared with the tap, the cutting condition is better. It is especially suitable for the thread processing of difficult to machine materials such as aluminum, copper, stainless steel, etc., especially for the thread processing of large parts and components of valuable materials, which can ensure the quality of thread processing and the safety of the workpiece.

(4) because there is no tool front-end guide, it is suitable for machining blind holes with short thread bottom holes and holes without undercut groove

Computer gong processing parameters

The gear parameters of the front center are: modulus M = 4, number of teeth z = 9, addendum height coefficient ha = 1, addendum clearance coefficient C = 0.25, radial modification coefficient X = 0.4, number of teeth across k = 2, common normal line wn = 19.5 + 0.2 + 0.1 (mm). CAXA does not provide professional gear modeling command, and can model through function curve, but this method is cumbersome and more difficult to model with modification coefficient.

It is not easy to ensure the size of the curve groove at the lower end of the front of the part, and the two 90 ° gaps are not closed. It is necessary to do auxiliary line closure before programming.

There are two ellipses with different directions on the inner contour edge of the back, the inner and outer hexagonal petals formed by arc, and two arc curve islands on the upper and lower sides. These elements need to be rounded in the processing, so it is more convenient to choose a reasonable shape.

1、 Analysis of parts processing technology

When CAXA is used to manufacture engineering parts, there is no need to draw complete parts for reprocessing. Firstly, the downtime is long and the processing time is wasted. Secondly, when selecting local processing, the elements of parts will interfere, which makes it inconvenient to get the program path.

When machining plane contour elements, the software supports only drawing out the contour line of parts for rough and finish machining. Surface machining can be programmed by solid or surface machining. Surface must be used to realize local machining, and some finishing commands can only use curved surface to select machining.

The rough machining command can not only realize rough machining, but also be used as finishing command.

The finishing command can use the track translation to form multiple levels, and the connecting track becomes a whole rough machining command; the rough machining command can change a layer of machining track into a finishing command by setting the layer height.

The plane contour elements of “CAXA Manufacturing Engineer” can use plane area rough machining and contour line finishing to finish the rough and finish machining of parts, and can also use contour finishing to do rough machining. Surface roughing can use equal height rough machining, or two finishing commands of parameter line finishing and three-dimensional offset surface for rough and finish machining.

Due to the high dimensional accuracy in the drawing, it is decided to use rough machining, semi finishing and finishing to achieve dimensional accuracy. Semi finishing and finishing use the same cutting tool and cutting parameters, which can correct various geometric errors of the cutter and elastic deformation of parts, and ensure the size easily. It is also necessary to finish the important bottom surface.

The part is processed by FANUC CNC machining center. All tool paths are generated according to FANUC post format, and the transmission uses CAXA’s own communication function according to FANUC settings. The larger surface program is processed online. The later processing programming ends with tool path. For parts such as box, bracket and connecting rod, the plane should be machined first and then the hole should be processed. In this way, the hole can be processed by plane positioning, which ensures the accuracy of plane and hole orientation, and brings convenience to the processing of holes on the plane.

2、 Machining datum plane first

In the process of parts processing, the surface as the positioning reference should be processed first, so as to provide the precise reference for the subsequent processing as soon as possible. It is called “benchmark first”.

3、 Finishing

The finishing of the primary surface (such as grinding, honing, finishing grinding / rolling, etc.) should be carried out at the final stage of the process road. After processing, the surface finish should be above ra0.9um, and slight bumping will damage the appearance. In Japan, Germany and other countries, after finishing, it is necessary to use flannelette for maintenance. It is absolutely forbidden to touch the workpiece directly with hands or other objects to avoid polishing The appearance of the finishing process is damaged by the transfer and installation between processes.

4、 Distinguish processing stages

The appearance with high machining quality is divided into three stages: rough machining, semi finishing and finishing. The first is to ensure the quality of processing; it is conducive to the rational use of equipment; it is convenient to organize the heat treatment process; and it is convenient to find the defects of the blank.

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

Positioning accuracy of computer gong processing

The positioning accuracy is about 10 μ M. High precision machining center, resolution of 0.1 μ m, maximum feed rate of 15 ~ 100M / min, positioning accuracy of about 2 μ M. In the range of 2-10 μ m, the more is ± 5 μ m, which can be called precision grade.

NC machining center NC  edit NC machining center is a kind of CNC machine tool with tool library and automatic tool change, which can carry out a variety of processing operations on the workpiece in a certain range.

The characteristics of machining parts on the machining center are: after the machined parts are clamped once, the CNC system can control the machine tool to automatically select and change the tool according to different working procedures; it can automatically change the spindle speed, feed rate, motion track of the cutter relative to the workpiece and other auxiliary functions, and automatically drill, countersink, ream, bore and screw on each machining surface of the workpiece Multi process processing such as grain, milling, etc. Because the machining center can finish many kinds of working procedures in a centralized and automatic way, it can avoid the artificial operation error, reduce the time of workpiece clamping, measuring and machine tool adjustment, as well as the time of workpiece turnover, handling and storage, and greatly improve the processing efficiency and accuracy, so it has good economic benefits. Machining center can be divided into vertical machining center and horizontal machining center according to the position of spindle in space.

Performance of computer gong deep hole drilling machine

The computer gong processing deep hole drilling machine is different from the traditional hole processing method. The computer gong processing mainly relies on the specific drilling technology (such as gun drill, BTA drill, spray drill, etc.), and the special machine tool for drilling the deep hole system with the length diameter ratio greater than 10 and the precision shallow hole is collectively referred to as the deep hole drilling machine. It has the following five characteristics in practical application

The casting of the whole machine is made of high-quality mihanna cast iron, and the aging treatment makes the casting structure uniform and stable, high rigidity and good stability.
Three coordinate deep hole drilling machine adopts imported high rigidity and high-speed CNC to process high-precision screw rod, which can provide more powerful torque and be more durable.
High quality servo motor and driver are used for three-dimensional feed drive, and they are directly connected with ball screw. Mechanical parts are processed and transmitted smoothly without backlash. At the same time, its good rigidity and optimized shock absorption performance greatly improve the dynamic rigidity of the transmission system and realize rapid movement.
The main shaft adopts powerful motor, which can meet the processing requirements of high and low speed. CNC machining and automatic oil cooling system ensure the constant temperature during processing.
The operating system adopts Taiwan system, which can be compatible with CAD / CAM software and can be more diversified.