JPS6012133B2 - Cold pilger mill pipe manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cold pilger mill pipe manufacturing method that is effective in increasing pipe manufacturing efficiency by being able to reliably feed a predetermined amount of material and increasing the feed rate.

As shown in Fig. 1, in this type of pipe manufacturing method, a material 2 is fed along a mandrel 1 which is rotatable around an axis and held immovable in the axial direction, at a tapered part of the tip of the mandrel. A pair of upper and lower rolling rolls each having a similarly tapered special gear IJ bar 3 (see the front view of the rolls in Fig. 2) installed on a roll stand 5 that can reciprocate at least a portion of the length of the taper at the tip of the mandrel. 4,
4, which performs tancho next rolling, which can increase the degree of processing compared to cold drawing etc. and improve pipe manufacturing efficiency, as well as produce pipes with less uneven wall thickness and excellent dimensional accuracy. It is known as a possible method. To explain in a little more detail, rolling is performed by moving the roll stand 5 back and forth, and one cycle of rolling is defined as the time when the roll stand 5 returns from the backward limit A to the forward limit B and back to the backward limit A.

In other words, the rolling rolls 4, 4 do not rotate completely, but rotate until point b (corresponding to forward rolling eye B and called forward point) coincides with point b' in the first half cycle, that is, the forward rolling process. , point a (
The material 2 is rotated and rolled until the retraction point (corresponding to the retraction limit A) coincides with point a'. The material 2 is fed in the axial direction by a predetermined length each time the roll stand 5 turns back the retreat limit A.

In addition, in synchronization with this, the material 2 is rotated together with the mandrel 1 by a predetermined angle (usually 60 degrees) so that the material 2 is evenly rolled from all sides. For this reason, the rolling rolls 4, 4
As shown in the developed view of Fig. 3, the caliber 3 maintains a constant distance between the caliber bottom 6 and the mandrel upper green 7 near the retraction point a (the part corresponding to the parallel part of the mandrel 1). Roll stand 5
The material 2 is released from the restraint of the rolling rolls 4, 4 until it turns around the retraction limit A, and this period becomes an idle process. The above is summarized in the rolling cycle diagram in Fig. 4, in which the roll stand 5 moves back and forth, resulting in an idle process, a forward rolling process, and a return rolling process (note that this return rolling process has a substantial effect on the material 2. It can be seen that the material 2 is sequentially rolled by a constant length by repeating the process (which is a simple return process without rolling) in order and giving feed and rotation to the material 2 in the idle process.

By the way, one of the problems with this type of pipe manufacturing method is that the material 2 and the mandrel 1 are stuck together.

That is, the material 2 and the mandrel are often stuck during the rolling process from forward rolling to return rolling, and in the next idle process, this sticking causes the problem that the material 2 is not uniformly fed by a predetermined length. . As a result, the dimensional accuracy of the tube decreases, and a large impact is applied to the feed mechanism for material 2 each time the material is fed.The above phenomenon becomes more pronounced as the feed amount of material 2 increases; In other words, if the material 2 and the mandrel turtle are separated before entering the idle process, it is possible to increase the feed rate to a large extent, resulting in a significant improvement in tube manufacturing efficiency. The present invention provides an ingenious and highly efficient pipe manufacturing method that actively utilizes a return rolling process that does not involve rolling to ensure separation of the material and mandrel. This is what we provide.

In the pipe manufacturing method of the present invention, the material is temporarily released from the restraint of the rolling rolls between forward rolling and return rolling, and during this period, a slight rotation in the circumferential direction is given to the material and the mandrel, and the material is The area near the boundary between the mandrel contact area and the non-contact area in the processing section corresponds to the bottom of the caliber of the rolling roll, and the material is peeled off from the mandrel by changing the rolling direction and performing the next return rolling. It is characterized by the following points.

The present invention will be explained in detail below. In this type of pipe manufacturing method as described above, the material 2 that has completed one cycle of rolling is, in extreme cases, as shown in FIG. Except for , the shape is slightly flattened from side to side.

This is why the material 2 is rotated by a predetermined angle every cycle, and the reason why the mandrel 3 can be rotated at the same time is because the material 2 is firmly attached to the upper and lower surfaces of the mandrel. None other than that.

Therefore, if material 2 is rotated from the solid line state as shown by the broken line between forward rolling and return rolling, and return rolling is performed in this state, material 2 will naturally roll through the mandrel due to the so-called ``kneading effect.'' It will be peeled off from. Here, in order to fully obtain the "kneading effect", the rotation angle 8 of the two rotations of the material between the forward rolling and the return rolling should be set as shown by the broken line, The boundary between the mandrel contact part X and the non-contact part X2 in the processing section, and the vicinity of the eye M, is set so as to correspond to the caliber bottom of the rolling roll (the center of the caliber bottom is located on the vertical line A). (Rotation angle 8?)
With this setting, in the immediately subsequent return rolling, the material 2 is processed in such a way as to give a slight reduction while largely releasing it in the circumferential direction, thereby producing the above-mentioned "kneading effect". The present invention utilizes this ``kneading effect'', and ``return rolling has a ``kneading effect'' to prevent the material 2 from sticking, which occurs during forward rolling, by applying special external force to the material 2 other than the rolling rolls. This problem can be easily solved by return rolling without adding any additives.

That is, the pipe manufacturing method of the present invention adds the following two points to the conventional pipe manufacturing method.

The material is released from the constraints of the rolling rolls between forward rolling and return rolling. That is, the material is made rotatable. During this time, rotation is given to the material in the circumferential direction. Regarding the first point, ``a new idle process (this is called a second idle process) should be provided between forward rolling and return rolling.

This is realized by changing the caliber shape of the rolling rolls 4,4. The caliber 3 of the rolling rolls 4, 4 has a non-rolled portion 8 that provides relief for the material in the range from before the advancing point b to the advancing point b, as shown in the developed view in Fig. 6. . If this rolling roll is used, the material 2 is released from the restraint of the rolling rolls 4 even when the roll stand 5 turns back from the forward limit B, and the material 2 can be placed in a rotatable state. The rolling cycle at this time is shown in FIG. The ratio of the non-rolled portion 8 to the total stroke must be comprehensively determined by taking into account the expected tube manufacturing efficiency and the expected state of adhesion between the material 2 and the mandrel.

In other words, if the range of the non-rolled part 8 is too large, the second idle process will become long, which may put pressure on the preceding and succeeding rolling processes and cause a decrease in rolling efficiency. If the range is too large, it becomes difficult to secure enough time to rotate the material 2 by the required angle necessary to expect the "kneading effect" in the second idle process. Regarding the second point, material rotation, it is only necessary to improve the rotation mechanism of the cold pilger mill.

To explain this point, let me briefly touch on the overall mechanism of this type of mill. The general mechanism of a cold pilger mill is vaguely shown in Figure 8. Material 11 is roll stand 1
It is supported by chucks 13 and 14 at the front and rear of 2, rotates in all directions around the circumference following a rotatable hollow shaft 15, and is movable with respect to the shaft 15 in the axial direction.

The mandrel 16 is inserted from the left side of the figure, and its tail end is fixed with a chuck 17, and a portion of the tapered tip reaches between the rolling rolls 18, 18 as the roll stand moves back and forth.
The main electric motor 19 is connected to a crankshaft 20 and reciprocates the roll stand 12 back and forth.

The movement of the roll stand 12 is controlled by a fixed rack and a pinion provided at the end of the roll shaft.
8 and 18 and rotates them. 21 is the weight of the crankshaft 20, and 22 is the mass balance.

The rotation of the main electric motor 19 is transmitted to the feed mechanism 24 for the material 11 via the crankshaft 20 and the transmission shaft 23, and further rotates the feed cam 25 once during one reciprocation of the roll stand 12 via the rotating shaft 29.

By the rotation of the cam 25, the material 11 is sent out in a fixed size in synchronization with the idle process. The pushing motion of the cam 25 is transmitted to the material 11 via the screw shaft 26 and the feed carriage 27. The screw shaft 26 rotates at a constant speed via the transmission shaft 23 and continues to move backward, and returns to its original position before the next extrusion and its base end contacts the cam 25. By adjusting the retraction speed of the screw shaft 26, the material 11
The feed amount is adjusted. For this purpose, the feed mechanism 24 includes a rotational speed control device (not shown) for the screw shaft 26. The rotation of the main electric motor 19 also causes the crankshaft 20,
A rotation mechanism 301 for the material 11 and the mandrel 16 is transmitted through the transmission shaft 23 and the rotation shaft 29 .

Like the feed mechanism 24, the rotating mechanism 30 has a cam 31, a screw shaft 32, and a gear 33 for reversing the screw shaft 32, and the cam 31 moves the screw shaft 32 once per cycle in synchronization with the idle process. Push out. The operation of the screw shaft 32 is transmitted to the connecting shaft 35 via the worm gear 34 as rotation interlocking, and the mandrel 1 is rotated at the base end of the mill.
6 is rotated, and the material 11 is also rotated at the tip, and both are driven synchronously. When rolling approaches the end, the feed carriage 27 is moved back to its original position, new material is inserted and set from the base end of the mill, and rolling is continued.

From the above explanation, it will be understood that in order to impart rotation to the material 11 in the second idle step, the design of the material rotation cam 31 may be changed.

Figures 9 and 10 show the designs of the conventional cam and the cam suitable for the method of the present invention.The developed view of the cam is shown in A of each figure, the speed diagram of the driven side is shown in the opening of each figure, and the acceleration curve of the same is shown in each figure. The figures are shown in each figure C. As is clear from a comparison of the two figures, the cam suitable for the method of the present invention has an operating portion 9 in a range corresponding to the second idle stroke in addition to the original idle stroke.
During forward rolling, the screw shaft 32, which continues to retreat along the slope 10, is pushed out at the same time as entering the second idle step, causing the material 11 to rotate together with the mandrel 16.

The screw shaft 32 is rotated at a constant speed by the action of the gear 33, and is retreating so that its base end always rests against the slopes 10 and 10', so when it enters return rolling, it starts retreating again. . The operation in the next idle step is as described in FIG. The shape of the operating portion 9 is determined from both the rotation angle of the material 11 in the second idle process and the second idle process time described above.

In order to adjust the rotation angle of the material 11, it is recommended to provide a rotation speed control device for the screw shaft 32, similar to that provided in the feed mechanism 24. If the material 11 is rotated by setting the rotation angle 8 as described in the explanation of FIG.
As described above, the material 11 is peeled off from the material 11, and as a result, the material 11 can be easily fed in the axial direction during the original idle process.

Therefore, the present invention not only achieves the intended purpose of increasing the amount of material fed and improving pipe manufacturing efficiency, but also improves dimensional accuracy by reliably feeding a predetermined amount of material in each rolling cycle. Not only does it have a great effect, it also prevents material from peeling off.
Because it utilizes the naturally occurring effect of the "kneading effect," there is no need to apply any special external force when peeling the material.In this way, material peeling can be done extremely easily without imposing a large burden on the mill mechanism. This is also a major feature of the method of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of the cold pilger mill pipe manufacturing method and is a vertical cross-sectional view, Fig. 2 is a front view of the rolling roll, and Figs. Developed diagrams for comparison: ``Figures 4 and 7 are rolling cycle diagrams of the conventional method and the present invention, Figure 5 is a vertical cross-sectional front view exaggerating the rolled state of the material, ``Figure 8 is a cold rolling cycle. A perspective view schematically showing the overall mechanism of the main part of the Pilger mill, Figures 9 and 10 are design drawings of the material rotation cam used in the subordinate method and the method of the present invention, and A is a developed view. indicates a velocity diagram, and C indicates an acceleration diagram. Explanation of symbols in the drawing: i, turtle?: mandrel, 2, military turtle: material 3: caliber, 4, wealth 8: rolling roll, 5
, 12: Roll stand, 31: Material rotation cam. Fig. 1 Blind 2 Fig. 3 Wing drawing Fig. 5 Box Fig. 6 *7 Fig. 8Z Fig. 9 Fig. 10 Face

Claims (1)

[Claims] 1. Material is externally charged into a mandrel having a tapered tip at the tip, which is rotatably supported in an axially immovable manner around an axis. A pair of upper and lower rolling rolls whose diameter in a specific range gradually decreases in one direction are rotated forward and backward in the length region of the mandrel taper part with the charged material being sandwiched between the two rolls by the forward and backward drive of the roll stand itself. In cold pilger mill pipe manufacturing, which performs diameter and thinning rolling by reciprocating motion, the material is temporarily released from the restraint of the rolling rolls between forward rolling and return rolling, and during this period, the material and mandrel are , the material is rotated in the circumferential direction so that the vicinity of the boundary between the mandrel contact part and the non-contact part in the forward rolling part corresponds to the caliber bottom of the rolling roll, and the rolling direction is changed between forward rolling and return rolling. A cold pinger mill pipe manufacturing method that is characterized by rolling.