JPH0527491B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a device for preventing bending of a metal tube after drawing in cold drawing. [Conventional technology] Drawing is performed with the main purpose of improving the dimensional accuracy, surface grade, and strength of the tube. However, during drawing, the main tube is deflected on the die entry side, making it difficult for the tube to approach the die entry side. By being deviated from the center of the die hole, and by being pulled out by a carriage through a gripper on the exit side of the die to a draw center that is different from the draw center on the die entry side, the stress on the upper and lower surfaces of the tube after passing through the die is increased. When a difference occurs and the drawing force is released, the amount of spring back will be different and bending will occur in the tube. In addition, the mandrel hangs down under its own weight, causing the plug to tilt, which shifts the relative positions of the die and the plug, resulting in non-uniform deformation in the circumferential direction and bending of the tube. When the tube is bent as described above, the following problems occur. In other words, it becomes impossible to process in the next process or to transport to the next process. Further, a bending process is required after drawing. Furthermore, the bending could not be done accurately,
Dimensional accuracy deteriorates during bending, and roll scratches, roll marks, pressing, etc. occur. Therefore, various measures have been taken in the past to prevent drawing bends in pipes. For example, two dies may be superimposed and the incoming die may be lightly drawn, or the die may be passed through without being processed to serve as a centering guide to the outgoing die. A method of centering the main pipe with the mandrel by attaching an auxiliary ring that is loosely inscribed in the inner diameter of the main pipe to the mandrel (Japanese Patent Laid-Open No. 51-9705). A method to prevent drawing bending of the main tube by adjusting the inclination of the die. A method of centering the main tube by inserting a small diameter tube into a drawing machine with a guide tube. A drawing method that applies repeated bending moments to the main tube on the exit side of the die. (Tokuko Showa 56-
20925), (Japanese Patent Publication No. 49-73360). etc., but all of these methods have drawbacks,
In this method, the diameter of the pipe becomes longer and the yield deteriorates, and since only the entry die has the role of centering, the main tube sags at a position far from the entry side, which has little effect on preventing bending and reduces the lubricant. Scratches are likely to occur due to peeling. This method is effective when the mandrel itself has high rigidity, but is less effective for small-diameter mandrels with low rigidity. Furthermore, it is necessary to prepare an auxiliary ring depending on the inner diameter of the main pipe, which takes time and effort for setup changes. In addition, this method largely depends on the skill of the operator, making it difficult to obtain a consistent effect, and the inclination of the dice cannot be adjusted unless several trial drawings are performed. It is necessary to prepare various tubes depending on the outer diameter of the main tube, and it takes time to change the setup. Both of these methods involve repeated bending straightening on the exit side of the die, and repeated bending under drawing force requires a large amount of energy. Particularly for large-diameter materials, the equipment would be too large, making it difficult to implement. [Problems to be Solved by the Invention] The object of the present invention is to provide a method that does not have the drawbacks of the above-mentioned conventional techniques, has high drawing efficiency, does not require setup changeover time, and does not cause deterioration in yield. An object of the present invention is to provide a device that effectively prevents bending of a pipe after drawing. [Means for Solving the Problems] The present invention relates to a cold drawing machine that is attached with a device that supports the main tube and the mandrel at a predetermined height on the die entry side of the drawing machine, and the present invention relates to a cold drawing machine that is attached with a device that supports the main tube and the mandrel at a predetermined height on the die entry side of the drawing machine. In inter-drawing, in order to support the main pipe and mandrel at a predetermined height on the die entry side, by inputting two or more sets of support devices equipped with rollers that move up and down, the diameter of the main pipe and the diameter of the mandrel, A computer control device that raises and lowers the rollers of the support device to a position where the main pipe or the mandrel is supported at a predetermined height, and a computer that recognizes when the tube end of the main pipe passes the position of the rollers of the support device and supports the main pipe or the mandrel at a predetermined height. The gist of the present invention is a cold drawing apparatus for metal tubes, which is equipped with a device for instructing a control device of the apparatus to change the roller to a predetermined height for supporting a mandrel. Referring to FIGS. 1A and 1B, the elevating mechanism of the support device 5, which supports the main tube 1 at a predetermined height starting from the entrance side of the die 3, and then supports the mandrel at a predetermined height, has a position. Select one that satisfies various conditions such as accuracy, response speed, load, and required stroke. Here, the predetermined height generally means the draw center, but due to the unique characteristics of the drawing machine, the bending effect may be improved by drawing at a height slightly different from the draw center. Furthermore, since the acceptable range for drawing without any practical problems is about ±2% of the outer diameter of the main tube, these conditions should be taken into consideration when designing. The suitability of several examples of elevating mechanisms for the present apparatus based on the accuracy, response speed, etc. is as follows.

[Effect]

Figures 2A and 2B show a state in which the present invention is implemented in a three-drum chain chain drawing machine, A is a front view showing a cross section at the support device installation position on the die entry side, and B is a line A--A in Figure 2A. It is a view taken along the line A. In the figure, 11 is a drum, and 13 is three tubes installed on the inner periphery of the drum.The main tube is inserted into this, and by rotating the drum 11, each of the three tubes is brought to the drawing position. Ru. 5 is a support device for lifting and lowering a V-shaped roller 6 to support the main pipe or mandrel, 7 is a lifting motor, and 8 is a speed reducer for carrying out the present invention. Needless to explain, drum 11 and tube 1
3 is provided with a slit through which the V-shaped rollers 6 of the support device can move in and out of the drum 11 and tube 13 in order to support the header or mandrel in the drum 11 and tube 13. The operation flow of the present invention will be explained based on the above-mentioned drawing machine. Inserting the main tube into the tube 13 → The arithmetic and control unit 9
Input the diameter of the main tube and the diameter of the mandrel used in After passing the pipe, the V-shaped roller at that position rises to the mandrel support height → drawing ends → the V-shaped roller 6 of the support device 5 descends at high speed → the drum rotates 11 times and stops at the drawing position of the next main pipe. [Implementation Effects] As a result of implementing the device of the present invention on a drum change, 3-draw 200T drawing machine, the drawing efficiency was the same as that of the conventional drawing machine before implementation, and there was no decrease in the drawing efficiency of the tube after drawing. The bending is conventionally 4/1000 ~
What used to be 5/1000 (mm) became 1/1000 to 2/1000 (mm) with the device of the present invention. As described above, in the cold drawing of metal tubes, the present invention is provided with a support device on the die entry side that supports the main pipe and the mandrel approximately at the draw center, and the support device automatically supports the main pipe at the center from the beginning. However, since the mandrel is automatically supported at the center after passing through the main pipe, it does not reduce drawing efficiency or yield, and prevents the pipe from bending after drawing. This has the effect of significantly improving tube production efficiency, including post-processing.

[Brief explanation of the drawing]

1A and 1B are explanatory diagrams of the mechanism and operation of the apparatus of the present invention, in which A shows the state before drawing and B shows the state during drawing. Figures 2A and 2B show a state in which the present invention is implemented in a three-drum chain chain drawing machine, A is a front view showing a cross section at the support device installation position on the die entry side, and B is a line A--A in Figure 2A. It is a view taken along the line A. 1: Mother pipe, 2: Mandrel, 3: Dice, 4:
Gripper, 5: Support device, 6: Roller, 7: Drive motor, 8: Reducer, 9: Arithmetic control device, 1
0: sensor, 11: drum, 12: drum support roller, 13: tube.

Claims (1)

[Claims] 1. In cold drawing of metal tubes, two or more sets of support devices equipped with rollers that move up and down to support the main tube or mandrel at a predetermined height on the die entry side;
A calculation control device that raises and lowers the rollers of the support device to a position where the main tube or mandrel is supported at a predetermined height by inputting the diameter of the main tube and the mandrel; Cooling of a metal tube characterized by comprising a device that recognizes the position of the roller when passing through the mandrel and instructs a control device of the support device to change the roller to a predetermined height of the mandrel support. Interval drawing device.