JPH0252564B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a method and apparatus for cold rolling pipes using the Pilger step process. To be more specific, there is a roll stand that moves back and forth,
Movement of the rolls in a pilger rolling machine comprising a roll forcibly rotated in the roll stand, a feeding mechanism for feeding the ingot in the axial direction of the mandrel rod, and a rotation mechanism for rotating the ingot around the tube axis. Regarding the relationship between the movement of the ingot and the feeding motion of the ingot.

b. Prior Art FIG. 3 is a conceptual diagram for explaining Pilger rolling.

The pilger rolling roll 13 is an ingot (hollow tube material) having a groove whose cross-sectional shape changes continuously on the roll circumferential surface, and into which a mandrel 14 is inserted.
The ingot 12 is rolled by reciprocating the roll stand from the ET point to the AT point of the ingot 12 while operating the roll. The ET point and AT point are the points where the direction of reciprocating motion is changed, and are the dead center on the entrance side and the AT point, respectively.
This is called the exit dead center. The groove of the roll 13 is from the point 13 _ET corresponding to the ET point to the points 13 ₀ , 13 ₁ , 13 ₂ ,
The depth becomes shallower in this order up to point 13 ₃ , and point 13 _AT, which corresponds to point AT, is formed deeper than point 13 ₃ .

The ingot (hollow tube material) 12 is the point 13 on the roll
When facing _{the ET,} it is rotated by a certain angle around the axis of the mandrel as necessary, and further parallel to the axis of the mandrel using a feed slide (not shown).
It is sent from the ET point to the AT point and is fixed at that position. Rolling is performed by moving the roll stand along the ingot from the ET point to the AT point with the feed slide fixed. This process is called the forward process. The tube is manufactured by returning the roll from the AT point to the ET point and repeating this process.

Furthermore, a patent has been applied for in Germany for a method in which when the ingot is released from the rolls at the AT point, the ingot 12 is given the necessary rotation and movement, and then rolled by the rolls 13 when the roll returns from the AT point to the ET point. This process is called the return process.

The method of carrying out most of the rolling process in the return process of rolls and stands has already been put into practical use.
This has the effect of significantly increasing production capacity when rolling pipes and significantly improving product tolerances.

c Problems to be Solved by the Invention However, the disadvantage of this method compared to the conventional technology is that the maximum horizontal rolling force exerted on the ingot on the feed slide in a stationary state during the rolling process increases significantly. It is recognized that this is true. This rolling force limits possible rolling processing in the return process, which limits the improvement in production capacity.

Moreover, it has already been revealed that the maximum value of the rolling force is located in the first 1/3 of the rolling caliber region in the return process, that is, in the region close to the ET point.

Based on the above-mentioned problems and knowledge, the object of the present invention is to reduce the maximum value of rolling force to a considerable extent, thereby reducing the load on the feed slide, which has hitherto been subject to method limitations. It is about removing the limits of production capacity.

d Means for Solving the Problems According to the present invention, when the ingot is rolled in the backward stroke of the roll stand, that is, in the return process, the reaction force acting on the rolls from the ingot reaches its maximum value. This was achieved by pulling the ingot backwards a certain distance in the area of processing.

e Effect: The pipe cross-sectional area of the ingot during pilger rolling increases as it approaches the dead center AT on the exit side to the dead center ET on the entrance side. Therefore, the dead center on the exit side
When the ingot is released from the rolling rolls at the AT point, if the ingot is sent in the direction from the ET point to the AT point using a feed slide and then rolled in the backward stroke, as the roll approaches the entrance side dead center ET, the roll load increases. In the present invention, when the roll approaches the entrance side dead center ET, the feed slide is pulled rearward. That is, the feed slide is moved in the direction from the exit side dead center AT to the entrance side dead center ET. This results in the ingot being pulled back, thereby reducing the rate of increase in the cross-sectional area of the ingot as the roll approaches the ET point. In other words, the reaction force acting on the roll from the ingot is reduced. This means that the load on the feed slide is reduced.

According to a preferred embodiment of the present invention, the distance by which the ingot is pulled is controlled in accordance with the magnitude of the reaction force. This control makes it possible to reduce the maximum value of the reaction force as desired, while keeping the reduction in pressure within the limits necessary for carrying out pilger rolling.

According to another embodiment of the invention, the distance the ingot is pulled backwards is mechanically controlled.

Furthermore, as an apparatus for carrying out the method of the present invention, in order to control the backward pulling movement of the ingot,
A device is proposed, characterized in that a prestressed spring element or similar mechanical force storage means is provided between the ingot and the feed slide or feed drive mechanism. When the rolling force is suitably high, by compressing this spring element it is possible to pull the ingot backwards through a predetermined distance depending on the spring properties of the spring element.

As another device for carrying out the method of the present invention, it is proposed that in order to mechanically control the backward pulling movement of the ingot, the means for controlling the movement of the ingot may be constituted by suitable means such as a cam disk. be done. This suggests that the feed drive mechanism of the ingot feed slide be modified in accordance with the findings of the present invention so that the ingot can be moved mechanically backwards in the rolling region where the horizontal rolling force is maximum. It means.

f Embodiment FIG. 1 is a diagram showing the relationship between the movement of a feed slide, which is an ingot feeding mechanism, and the movement of a roll stand, which moves rolls.

During the period a including the entrance side dead center ET point, the ingot is released from the rolls, rotates around the mandrel axis, and is fed parallel to the mandrel axis. The amount of feed movement parallel to the mandrel axis in this region is i+e.

In period b, the feed slide is fixed and a forward stroke of rolling is performed in which the roll moves from the entrance side dead center ET to the exit side dead center AT.

During period c, which includes the dead point AT on the exit side, the ingot is released from the rolls, and the ingot is rotated and moved. The amount of feed movement parallel to the mandrel axis during this period is designated by f.

In period d, rolling is performed in a backward stroke in which the roll returns from the exit side dead center AT point to the entrance side dead center. In this stroke, unlike the forward stroke, the feed slide is fixed in the first half, but is pulled back during the second half period h. The amount of pullback is indicated by i.

In the end, the ingot feed amount during the entire round trip is e+
It is f.

FIG. 2 is a conceptual perspective view of an embodiment of a feeding mechanism according to the present invention that mechanically controls the amount of ingot feeding using a cam.

The rotating shaft 1 rotates the cam 2 at a constant rotation speed. The cam has a shape corresponding to the feeding of the ingot at both dead centers ET and AT in FIG. 1, and the feeding spindle 6 reciprocates in the axial direction via the roll 3 and lever 4 that are in contact with the cam. The amplitude of the movement of the lever can be adjusted by moving the fulcrum of the lever steplessly by moving the fulcrum member 5.

On the other hand, the rotation of the shaft 1 is transmitted to the feed spindle 6 via the stepless regulator 8 and the gear train 9, 10, 11, and feeding is effected by a mechanism not shown.

g Effect As a result of experimentally adopting the method according to the present invention, 2
When the feed slide is pulled backward by about 8 mm from the ingot, the maximum value of the reaction force acting on the roll from the ingot can be reduced by about 30 to 70 percent compared to the value measured when the present invention is not applied. was revealed. Moreover, with the implementation of the method according to the invention, the deformation area in which the ingot is pulled backwards can necessarily be reduced, which in practice
It has been demonstrated through measurements and theoretical studies that there are no disadvantages.

The present invention is carried out as described above, and since the maximum value of rolling force can be reduced, the production capacity of the rolling apparatus can be increased. This is because the limit of possible rolling processing determined by the magnitude of rolling force can be moved.

[Brief explanation of drawings]

Fig. 1 is a forward/backward stroke diagram of the present invention, Fig. 2 is a conceptual perspective view of the sending/returning mechanism of the present invention, and Fig. 3 is a conceptual perspective view of the sending/returning mechanism of the present invention.
The figure is a conceptual diagram illustrating a Pilger rolling machine. a...Rotation/feeding period, b...Advance/rolling period, c...Rotation/feeding period, d...Backward/rolling period, e, f...Advance amount, g...Backward, h...Deformation period , i... Retraction amount, 1... Rotating shaft, 2... Cam, 3... Roll, 4... Lever, 5... Fulcrum member, 6... Feed spindle, 7... Roll stand, 8... None Step adjuster, 9, 10, 11...gear.

Claims (1)

[Claims] 1. A roll stand that moves back and forth, a roll for pilger rolling that forcibly rotates inside the roll stand, a feeding mechanism that feeds an ingot as a tube material in the axial direction of the tube, and an ingot rolling stand that moves back and forth; In a method of cold rolling a tube using a Pilger rolling machine equipped with a rotation mechanism that rotates the ingot around the tube axis, when the ingot is rolled in the return process in which the roll stand returns from the exit side dead center AT to the entrance side dead center ET. In the area of the rolling process where the reaction force acting on the rolls from the ingot reaches its maximum value, the ingot is moved to the dead center on the exit side.
A method of cold rolling a pipe using the Pilger step method, which is characterized by pulling and moving the pipe in the direction from AT to the inlet dead center ET. 2. A method for cold rolling a pipe using the Pilger step method according to claim 1, characterized in that the distance by which the ingot is pulled backward is controlled in accordance with the magnitude of the reaction force. 3. A method of cold rolling a pipe using the Pilger step method according to claim 1, characterized in that the distance by which the ingot is pulled backward is mechanically controlled.