Qiqihar North Machinery Co., Ltd. (Heilongjiang 161000) Zhao Xiangyu has four main methods for thread processing: the first one is turning, which is mainly used to machine the thread of various rotary parts; the second is the collision, mainly used for Non-rotating body parts and hole type thread processing with higher positional accuracy (as shown); the third type is processing method such as rolling wire, mainly used for mass production of standard parts; the fourth type is bench work, mainly For threads that are not suitable for machining.
As a main processing method, boring is widely used in the processing of thread. Previous thread processing was mainly done using a conventional horizontal boring machine. With the development of numerical control technology, CNC boring machines are widely used in all aspects of production. There are many machining methods for CNC boring machines in thread machining. In the following, only the main methods of machining the thread of the CNC boring machine are analyzed from the aspects of programming, tool and application range.
The processing principle is that the machine tool performs helical interpolation while milling the material of 018mm aluminum rod (LY12), and the cutting fluid used is QL-3L type cutting fluid produced by Beijing Powerful Cutting Fluid Factory.
The handle machining program is as follows (partial): cutting, that is, the machine tool performs circular interpolation in the plane of the shaft, and the Z-axis performs corresponding linear interpolation to form a spiral line which is consistent with the thread pitch of the machined thread. In the thread milling process of the CNC boring machine, the running path of the machine tool is a spiral line. The feed rate of the machine tool and the spindle speed are independent of the pitch of the thread. Therefore, the feed rate and spindle speed of the machine tool can be adjusted in real time during the cutting process. In the ordinary horizontal boring machine threading process, the machine tool performs a simple linear motion, and the feed rate and spindle speed cannot be adjusted.
G3, TURN instructions. In the following, the machining of the M125x2-6H internal thread in the illustrated part is taken as an example to introduce the thread milling of the CNC boring machine.
In the program, G2 represents a circular arc motion in a clockwise direction; G3 represents a circular arc motion in a counterclockwise direction; the end point coordinates of the XYZR table spiral interpolation; IK represents the axis coordinate of the spiral; TURN = an integer representing the spiral Number of turns. In actual programming, it should be noted that if the number of turns of the helical interpolation is just an integer /V circle, then TURN=(/V-1) in programming; if the number of turns of the helical interpolation is a non-integer circle/ When V. /1 lap, the TURN=/V in the programming is to round off the fractional part of the U circle. For example, the number of turns of the helical interpolation is 8.9 laps, then TURN=8 in the programming. After the practice, the above method is used. The handle of the part has no burrs on the end face. After the processing is completed, it is only necessary to use the polishing sandpaper to gently drop the end face. Because the tool cuts the workpiece and also turns and turns the left end of the workpiece. () 2 internal grain program, the length of the spiral is 32mm, the susceptibility is P=2mm, so the total 16 (the length of the squall line is 32/嫘 2) is the distance (integer circle), then TURN=(16-1) : Programming, execute feedrate C00T1D1Z200M03S600; fast run to Z200, use TID1 tool parameter, spindle forward rotation 600r/min interpolation to XOYO, feed rate 500mm/min Y-62.784, Z-120.5; axis of suspected rotation The heart coordinate is 1062.784 (relative coordinate with the starting point of the sinus line as the origin); the number of turns of the squall line is 16 TURN=15(16-1)N45Z100F500; the linear interpolation is to Z100, the feed rate is different due to different processing principles, CNC Trampoline spiral interpolation method The tool used for processing the grain is very different from the thread of the ordinary horizontal boring machine.
In mass production, the CNC boring machine can be machined with an indexable internal thread cyclone milling cutter. The tool is a machine clamp type with multiple cutting edges. The spindle is cut multiple times per revolution. The insert is made of hard alloy and can be used. High cutting speed and high processing efficiency (as shown in a). In medium-volume production, it can be machined with an indexable single-blade thread milling cutter. The tool is clip-on but only has one cutting edge. The spindle is only cut once per revolution. Since the blade used is a coated carbide insert, Achieving high cutting speeds, low machining efficiency and low tool costs (as indicated by b). In single-piece and small-volume production, it can be processed with the combination of hard alloy ordinary inner butterfly boring head and rough boring bar. This tool is characterized in that only one cutting edge is welded carbide structure and the cutting speed is low. Low processing efficiency, but good tool versatility and low cost, suitable for processing a wide range of threads (as shown in c).
2. Milling thread combs using boring cutters (knife combs) can be divided into two types: machine clamp type and integral type. The overall structure has a plurality of cutting edges, and each blade has a plurality of cuts and is processed. The threaded solid part has the same size groove, the standard pitch is between the groove and the groove, there is no thread rising angle between the groove and the groove, and the chip pocket is opened on the cutter body. The machining principle of using a thread comb is similar to that of a CNC boring machine. The difference is that the threaded comb can only be threaded with one revolution. In order to complete the processing of a thread, TURN=U-1) in the program, that is, TURN=0, the TURN parameter is omitted. The structure and processing method of the thread comb are as shown. In order to conveniently control the size of the machining thread, use parameter R1 to record the radius value of the tool, and adjust the value of R1 to adjust the size of each upper knife and the size of the machining thread. The procedure for machining the M125x2 internal thread in 1 is still used. For example, the program is programmed: programming, executing the feed per minute Z200, using the T1D1 tool parameter, the spindle forward rotation 200r/min cancels the tool radius compensation, linear interpolation to X0Y0, feed rate 500mm/min25 2-8.5; Linear interpolation to 7-8.5N30XOY=-62.784+R1F200; linear interpolation to the starting point of the spiral R1Z-120.5I0=62.784-R1; clockwise helical interpolation, the end point of the rotation is X0Y= -62.784+R1Z-120.5 The axis coordinate of the rotation line is 10=62.784-R1 (relative coordinate with the starting point of the rotation line as the origin), the number of turns of the squall line is 1 circle TURN=0 is omitted in the program â–² cold-working CNC boring machine uses thread comb to machine thread It has the advantage of high processing efficiency and is suitable for mass production. However, its limitations are also great. First of all, the versatility of the tool is poor. Each blade of the clip-on comb can only process a thread with a fixed pitch. For different types of threads, the corresponding blade must be purchased, and the integrated thread comb is also Only threads with a fixed pitch can be machined, and different types of threads must be re-purchased or manufactured. Secondly, the thread comb is not suitable for processing large pitch and thread length, mainly because of its large cutting edge length and intermittent cutting. The cutting force is large during the machining process, and the tool is prone to elastic deformation and cause errors. Moreover, if the thread length is greater than the length of the blade, the depth of the feed increases, and the thread comb will lose the advantage of high processing efficiency. The third is the high price of the thread comb, which is expensive to use in single-piece and small-batch production.
3. Imitate the ordinary trampoline, and use the method of proportionally rotating the spindle speed and feed. The tool used in this method is the same as the tool used in the ordinary boring machine thread. There are two main types, the hard alloy common internal thread boring tool. The head is machined with a rough boring bar. The machining method is difficult to adjust the tool accurately, and the technical level of the worker is high; the CNC boring machine with complete equipment attachment can be threaded by the multi-function rotary cutter holder (small tool holder), which can complete the thread and 镗Holes, grooving, cutting planes, 镗 external circles and other processing, easy to achieve accurate adjustment of the tool radial dimension, low requirements for workers' technical level. This machining method can be programmed with the compensation fixture tapping command G63 (flexible tapping command). Due to the processing principle, the principle of programming is: unit time feed /= unit time spindle speed nx pitch P. The feed and spindle speed trim switch is set to 100% by the G63 command. That is, during the execution of the G63 command, the feedrate/ and the spindle speed per unit time n can only be fixed values ​​set in the program, and on the machine. The spindle and feedrate override switch are disabled. In the machining, the fine adjustment device of the multi-function rotary cutting tool holder is used to accurately adjust the radial dimension of the tool, thereby controlling the size of the thread to be processed. For example, the machining of the M125x2 internal thread is still taken, the pitch P=2mm, when the absolute coordinate is programmed, the feed per minute is executed, the spindle orientation SPS=G4Fm; the machining Os G40G7G0X0Y0F5OO is paused; the working plane is selected as G17 flat, the tool radius is canceled. Compensation, linear interpolation to X0Y0, feed rate 500mm/min (knife stove away from sweat Li machining plane, to prevent scratching the thread during retraction) Several processing methods introduced above, due to processing principles and the use of tools and other factors, generally Suitable for threading with large diameters. For smaller diameter threads, we use tap tapping to machine. The tapping of the CNC boring machine can be divided into two types: rigid tapping (tapping without compensation jig) and flexible tapping (using the offset of the compensating jig). The two tools used are the same taps. However, the requirements for machine tool functions during machining are different from those used. Rigid tapping requires that the spindle of the machine tool must have a spindle orientation function, and the rigidity of the spindle is required to be high. The tap used can be clamped with a powerful milling chuck. Flexible tapping does not require the machine to have a spindle orientation function, but the tap must be clamped using a tapped chuck holder. The chuck has an overload protection function, which can automatically unload after the cutting load of the tap exceeds a certain range to prevent the tap from breaking. Rigid tapping and flexible tapping can not be used for the second thread after the first tapping of the same thread. Otherwise, it will be caused by the inability to align the knife; but the rigid tapping is due to its The spindle orientation function allows multiple tapping of the same thread in one setup without changing the tool. Flexible tapping does not have this capability. The thread is machined by the rigid tapping method. During the machining process, the spindle speed can be adjusted manually by the spindle speed override switch according to the actual production situation. At this time, the feed rate of the machine tool is automatically adjusted proportionally to the spindle speed by the CNC system to ensure the advancement. The proportional relationship between the amount of the feed and the spindle rotation is in accordance with the suspected distance of the thread being machined. However, due to the large cutting force of the tapping process and the large change of the cutting force during the spindle speed adjustment, the tap is easily damaged. Therefore, in the rigid tapping process, the cutting parameters such as the spindle speed should be avoided as much as possible. In the block before the rigid tapping command, the spindle orientation command SPOS= must be used for spindle orientation. Rigid tapping is programmed with the G331 and G332 commands.
Box cold plus I where X, Y, Z represent the depth of the tapping thread, and 1 represents the pitch of the X-direction tapping thread, the pitch representing the Y-direction tapping thread, and K represents the pitch of the Z-direction tapping thread. The symbols of I, K are It means that the spindle is rotated clockwise and the thread is right-handed. The symbol is negative. The spindle is counterclockwise. The thread is left-handed. The programming method is described below by taking the rigid tapping of the M24x 3 threaded hole as an example.
Programming, the feed parameter is executed as the plane G17 plane, linear interpolation to XOYO, feed rate 500mm/min N25Z6; linear interpolation to Z6N30SPOS=0; spindle orientation SPOS=0N35G331Z-36K3S20; rigid tapping depth end point is Z-36, right-handed striated pattern, suspected distance 3mm, spindle speed 20r/min N40G332Z6K3; rigid attack pattern returned to Z6, pitch 3imn due to the difference of processing principle, the tool setting method on the tool setting tool before machining There are differences, such as the use of media rotary interpolation milling thread and multi-function rotary cutting tool holder to process the crepe, the accuracy of the cutting edge angle should be ensured when a is set, the two cutting edges are symmetrical with the horizontal direction and the theoretical cutting edge The extension of the angle is tangent. At this time, the value displayed by the tool is the length and radius of the tool. It should be noted that the radius of the corner of the tool should be smaller than the radius of the bottom of the thread. When using the thread comb to machine the thread, in addition to ensuring the above points, the rounding error of the tool should also be checked to ensure that the plane of each cutting edge is on the same cylindrical surface when it is rotated around the reference axis (the axis of the tool holder and the spindle). Inside. When the part structure allows, the second pitch cutting edge of the tool can be used as the tool point of the tool length. At this time, the first pitch cutting edge with the worst tool strength does not participate in the cutting, which can prevent the damage of the tool and improve the tool. life. In rigid tapping and flexible tapping, since the tool is used as a tap, it is only necessary to measure the length of the tool without regard to the radius.
Among various thread processing methods, spiral interpolation milling and crepe is a relatively special processing method. In actual production, there was a batch of casting box parts that were threaded after partial repair welding. They could not be processed by various processing methods. The reason for the analysis was that the hardness of the repair joint was 篼, and the tool was at the repair joint. The cutting force is much larger than that of other unwelded positions, which can cause serious knife-shaping. In the case of other unwelded positions, the threaded column cannot pass at the repair joint. After the analysis, the thread is interpolated by the method of helical interpolation, because the cutting force of the helical interpolation milling thread is the smallest in various processing methods, and the amount of back-feeding is reduced in the processing, The second pass, the reduction of feed in the repair welding position and other measures, after the use of thread sample column inspection, thus avoiding the scrapping of this batch of products, there is a certain reference in actual production.
The above several methods for processing the median boring machine are summarized.
The machining principles, programming methods, machining tools and the items to be noted in the machining methods used in these several machining methods are different. In use, it is necessary to select according to the actual production conditions. The programming method described in this article is based on a CNC boring machine using the SIEMENS 840D operating system and differs in programming and processing due to the different settings of the machine tool manufacturer. The use of CNC boring machines to machine non-rotating body parts and threading of high-position hole-type parts can improve machining efficiency, reduce tooling design, and provide a good guarantee for the accuracy of the machined parts. () Israel's "Urban Aviation" company used CimatronE software to design the world's first automotive vertical takeoff and landing aircraft mrnE to design the new X-Eagle aircraft. Another model of the car that City Airlines and Bell Helicopters developed was used to carry the army.
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