JPS63194815A - Cold drawing apparatus for metal pipe - Google Patents

Abstract

PURPOSE:To minimize bending a pipe after drawing, by providing supporting devices for a base pipe and a mandrel on the inlet side of a die and by supporting the base pipe at a starting and the mandrel after the base pipe is passed. CONSTITUTION:The two supporting devices 5 or more having rollers 6 capable of elevating up and down to support the base pipe 1 and the mandrel 2 at a prescribed height are provided on the inlet side of the die 3 of a drawing apparatus. Further, an arithmetic and control unit 9 calculating the supporting height of the base pipe 1 and the mandrel 2 by inputting the diameter of the base pipe 1 and that one of the mandrel 2. Then, the base pipe 1 is supported by the rollers 6 at starting and after the base pipe 1 is passed, the passing is detected by a sensor 10, the mandrel 2 is supported changing the rollers 6 height through the arithmetic and control unit 9. As a result the pipe bent after the drawing is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for preventing bending of a pipe after drawing in cold drawing of a metal pipe.

[Conventional technology]

The main purpose of drawing is to improve 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 from the die hole center. Due to the deviation, and on the other hand, on the exit side of the die, the tube is pulled out via a gripper to a draw center different from the draw center on the die entry side, which causes a stress difference between the upper and lower surfaces in the axial tensile stress of the tube after passing through the die. When the drawing force is released, the amount of spring bank changes and bends occur in the tube.

Furthermore, the mandrel hangs down due to its own weight, causing the plug to tilt, causing the relative positions of the die and the plug to shift, resulting in non-uniform deformation in the circumferential direction, causing bending in the tube.

When the tube is bent as described above, the following problems occur.

In other words, it becomes impossible to process the product in the next process or to transport it to the next process. Further, a bending process is required after drawing. Furthermore, the bending cannot be done accurately, resulting in poor dimensional accuracy and occurrence of roll flaws, roll marks, pressing, etc. during bending.

Therefore, various measures have been taken in the past to prevent drawing oil from forming on the pipes.

For example, ■ A method in which two dies are superimposed and the incoming die is used to lightly draw the die, or the die is 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 of preventing drawing oil in 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 method of drawing while applying repeated bending moments to the main tube on the exit side of the die. (Special Public Interest Publication No. 56-20925), (
Japanese Patent Publication No. 49-73360).

However, all of these methods have drawbacks; in method (2), the die part becomes long, resulting in poor yield; and because only the entry die has the role of centering, In this case, the main pipe sags, the effect of preventing bending is small, and flaws are likely to occur due to peeling of the lubricant.

Method (2) 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, method (2) 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.

(2) It is necessary to make small teeth for each type of tube depending on the outer diameter of the main tube, and it takes a lot of time to change the setup.

Method (2) all involves repeated bending correction 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.

[Problem that the invention seeks to solve]

It is an object of the present invention to have high drawing efficiency without the drawbacks of the above-mentioned conventional techniques, to eliminate the need for set-up time, to avoid deterioration of yield, and to improve the bending of pipes after drawing. To provide a device to prevent this.

[Means for solving problems]

The present invention relates to a cold drawing machine that is equipped with a device that supports a main pipe and a mandrel at a predetermined height on the die entry side of the drawing machine. and to support the mandrel at a predetermined height,
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, the rollers of the support device can be raised and lowered to a position where the main pipe or mandrel is supported at a predetermined height. A computer control unit that recognizes when the end of the main pipe passes the position of the rollers of the support device,
The gist of the present invention is a cold drawing apparatus for metal tubes, which includes a device for instructing a control device of a support device to change the roller to a predetermined height for supporting a mandrel.

Referring to FIGS. 1(A) and 1(B), starting from the entrance side of the die 3, the main pipe l is supported at a predetermined height, and then the lifting mechanism of the support device 5 that supports the mandrel at a predetermined height is shown. Select one that satisfies various conditions such as positioning accuracy, response speed, load, and required stroke.

The predetermined height here generally means the draw center, but depending on the characteristics of the opening of the drawing machine, the bending effect may be improved by drawing at a height slightly different from the draw center. In addition, the acceptable range for drawing without any practical problems is ±2% of the outer diameter of the main pipe.
Therefore, the design should take these conditions into consideration.

The suitability of several examples of elevating and lowering mechanisms for this Via from the above-mentioned accuracy, response speed, etc. is as follows.

By using a V-shaped roller as the roller 6 of the head of the support device 5, movement in the direction perpendicular to the axis is restrained, and positioning is performed accurately.

For example, in the case of three main rivers, the number of supporting devices 5 to be arranged is such that one set includes three V-shaped rollers installed on the same axis, and one
At least two or more sets are arranged on the 30-person side of the die in the axial direction.

The arrangement of the support device is as shown in FIGS. 1(a) and 1(b).
The distance to the tube fi (tube end), that is, the overhang length of the main tube from the farthest roller is a1, and the distance from the die 3 to the farthest supporting device roller salt is b, then a≦b, and from the die If the distance from the recent support device roller to the die 3 is C, it is desirable to make the distance C as small as possible. Taking into consideration the above conditions, the arrangement interval and the number of arrangement so that the main pipe does not curve are determined.

An elevating drive device 7 is attached to the support device 5.

Reference numeral 9 in FIG. 1 is an arithmetic control device which calculates a predetermined height of the V-shaped roller 6 of the support device 5 by setting the diameter of the main pipe to be used, and by setting the diameter of the mandrel to be used. A predetermined height h2 of the V-shaped roller 6 of the support device is calculated. These settings are performed using a method such as setting with a digital switch. By pressing the operation support button (not shown), the V-shaped rollers 6 of all the support devices will reach the height hl that supports the main pipe l approximately at the drawing center before drawing starts.
Rise to and! 1! Completion of preparation is confirmed.

Reference numeral 10 in FIG. 1 is a sensor for detecting when the tube end of the main tube passes through the supporting device 5, and a known sensor such as a mechanical type or a photocell type can be used.

Each sensor 10 is attached to the arithmetic and control device of each support device 5, and when the main tube end passes the position of the V-shaped roller 6 of the support device, it emits a signal to the arithmetic and control device 9, and based on the signal, The V-shaped roller 6 of the support device is automatically changed to a height of h2. That is, it rises to a height that supports the mandrel 2 approximately at the center of the drawer. The end of the main pipe is detected by the sensor lO mentioned above, and also by calculating the processing rate, roller arrangement distance, main pipe length, etc. by the control machine, depending on the moving distance of the drawing machine carriage, and detecting the end of the pipe. You can do it like this.

[For production]

Figures 2 (a) and 2 (b) show the state in which the present invention is implemented in a chain drawing machine for three drum changes, and (a) is a front view showing a cross section at the support device installation position on the die entry side; 1 is a view taken along the line A-A in FIG.

In the figure, 11 is a drum, and 13 is three tubes installed on the inner periphery of the drum.The main pipe 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 elevating the ■-shaped roller 6 to support the main pipe or mandrel in order to implement the present invention; 7 is a lifting motor; 8 is a speed reducer; 6 Needless to say, the drum 11 and The tube 13 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 within the drum 11 and tube 13.

The operation flow of the present invention will be explained based on the above-mentioned drawing machine. (1) Inserting the main pipe into the tube 13 - Entering the diameter of the main pipe and the diameter of the mandrel to be used in the arithmetic and control unit 9 with great force - 11 rotations of the drum;
Stop at the drawing position - Rise of the ■-shaped roller 6 of the support device 5 At a general constant height, the V-shaped roller stops rising and supports the main tube - Drawing starts - After passing the main pipe, the V-shaped roller at that position rises to the mandrel support height - Drawing End - 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 1200T drawing machine with drum change of 3 drums, the drawing efficiency was the same as that of the conventional drawing machine before implementation, with no comparable decrease, and the bending of the pipe after drawing was reduced. , conventionally 4/1000 to 5/1000
(mw), but with the device of the present invention, it is 1/1000
~2/1000 (Cao Zhen).

The present invention is as described above (in cold drawing of metal tubes, a supporting device is provided on the die entry side to support the main pipe and the mandrel approximately at the draw center, and the supporting device automatically moves the main pipe to the center at the beginning). Since the mandrel is automatically supported at the center after passing through the main pipe, the drawing efficiency is not reduced, the yield is not reduced, and bending of the pipe after drawing is well prevented. This has the effect of significantly improving the production efficiency of tubes, including subsequent processes.

[Brief explanation of the drawing]

FIGS. 1A and 1B are explanatory diagrams of the mechanism and operation of the apparatus of the present invention, in which FIG. 1A shows the state before drawing and FIG. 1B shows the state during drawing. Figure 2 (a) shows a three-drum change chain drawing machine in which the present invention is implemented, and (a) is a front view showing a cross section at the support device installation position on the die entry side. B) is a view taken along the line A-A in FIG. 1: Main tube, 2: Mandrel, 3: Dice, 4 Nigelipper-15: Support device, 6: Roller, 7: Drive motor, 8
: Reduction gear, 9; Arithmetic control unit, 10: Sensor, II drum, 12 Ni drum support roller, 13: Tube. Purchase; 2nd 2nd (a)

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 pipe or mandrel at a predetermined height on the die entry side, the diameter of the main pipe and the diameter of the mandrel are used. By inputting , the computer control unit 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 when the pipe end of the main pipe passes the position of the rollers of the support device. , a device for recognizing this and instructing a control device of the support device to change the roller to a predetermined height for supporting the mandrel.