JPS62238010A - Inertial force balancing device for pilger type rolling mill - Google Patents

Abstract

PURPOSE:To decrease unbalanced external force as far as possible and to make stable operation with a small balancing device by balancing the inertial force of a rolling mill which converts rotating motion to reciprocating motion by springs and selectively controlling spring constants by rotating speeds. CONSTITUTION:The rotation of a crank arm 3 by a motor 1 is transmitted by a connecting rod 5 to a stand 8 of a Pilger mill 7 so that the stand moves back and forth. The stand is supported by the springs 10 having the spring constant corresponding to the max. rotating speed in this case to absorb the inertial force. The changed rotating speed of the arm 3 is detected by a tachogenerator and rotating angle detector 11 and the spring combination conforming to the calculated 12 correction spring constant is selected by a spring constant varying device 13 and is assembled to the springs 10. The above- mentioned device 13 is operated to select the spring set having spring constants K1-K4 as desired by selectively pushing cylinders 21, 22. The unbalanced external force is minimized by the above-mentioned technique and the inertia force of various reciprocating force is absorbed by the smallest balancing device, by which the stable operation of the rolling mill is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inertial force balance device for a Pilger type rolling mill for manufacturing seamless steel pipes and the like.

[Conventional technology and its problems]

In general, a Pilger type rolling mill equipped with Pilger mill rolls uses a blank tube between a pair of Pilger mill rolls with a special caliber and a mandrel rod, as shown in Japanese Patent Publication No. 5m-43472. to produce seamless steel pipes. Its configuration and operation are
To explain this using the schematic diagram of the conventional example shown in the figure, a crank arm 3 and a fan-shaped balancer 4 are fixed to a crankshaft 2 rotated by a main motor, and a fan rod 5 is attached to the crank 7-m 3.
and (2) A connecting rod 6 for a balancer is connected to the tip of the connecting rod 5, and a pair of pilger mill rolls 7.
At the same time, the balancer 9 is suspended from the tip of the connecting rod 6 for the V balancer.

When the main motor rotates the crankshaft 2 at a constant rotational speed ω, the pilger mill stand 8 reciprocates via the crank arm 3 and connecting rod 5. Along with the reciprocating motion, the Luger mill roll 7 is rotated by a rank and binion (not shown), and rolls the raw pipe. To put this further into perspective, when the Pilker mill roll 7 rotates and the raw pipe into which the mandrel rod is inserted moves forward, the roll 7 bites into the raw pipe, and as the roll 7 rotates further, the raw pipe reaches its finished dimensions. After being rolled, the blank tube is removed from the contact of the rolls 7. On the other hand, the raw tube stops while being rolled by the rolls 7, but moves forward as soon as it becomes free from the rolls 7.

As described above, the Pilger rolling mill employs a crank mechanism to reciprocate the Pilger mill stand 8 on which the Pilger mill roll 7 is attached, and the reciprocating motion induced by the crank motion Unbalance occurs due to the inertial force of the inertial force and the couple due to the inertial force. In order to eliminate this imbalance, the fan-shaped balancer 4 and the V-balancer 9 are provided as described above.

However, in the conventional pilger rolling mill, the following disadvantages arise due to the installation of the fan-shaped balancer 4 and the V-balancer 9.

That is, 1) the fan-shaped balancer 4 and (2) the balancer 9 are installed, so the size becomes large. 2) In the fan-shaped balancer 4 and the V-balancer 9, the first-order term is based on the rotational speed ω of the crankshaft 2 (this is the first-order term in the well-known general formula expressing reciprocating inertia force).

(same below) can be eliminated, but the unbalance of higher-order terms cannot be eliminated. In order to reduce the unbalance of the higher-order terms, the crank arm 3
Since the ratio of the length R of the connecting rod 5 to the length of the connecting rod 5 must be made small, the length of the connecting rod 5 becomes large.
The entire device becomes larger. 3) Rotational speed ω of crankshaft 2
Since there is no imbalance in the higher-order terms of
Because the connecting rod 5, crankshaft 2, etc. receive a large inertial force proportional to the square of There is. 4) ■In order to provide the balancer 9,
For example, a pilger for rolling a φ260fi raw pipe.
The mill crushing machine requires foundation work approximately qm deep, which in turn makes maintenance around the V-bar difficult.

On the other hand, in a pilger rolling mill that reciprocates a pilger mill stand equipped with a pair of pilger mill rolls,
An inertial force balance method is known in which the piston loft of an air cylinder is connected to the Luger mill stand, and compressed air is supplied to the air cylinder to balance the inertia of the reciprocating motion of the cough and the Luger mill stand. (See British Patent No. 1355733, Book II).

However, in this known inertial force balance method, since the inertial force is balanced by compressed air whose volume can be reduced, not only the compressor and air cylinder for compressed air become large, but also the compression If an attempt is made to balance the inertial force of the reciprocating motion by driving the air cylinder with air, an excessive amount of energy will be required for the driving source.

[Means for solving problems]

Therefore, the present invention was created in order to solve all of the problems of the prior art at once, namely, to balance only the first-order term of inertia of the reciprocating motion of the pilger mill stand on the pilger mill stand. An object of the present invention is to provide an inertia force balance device for a pilger rolling mill, which is equipped with a spring and whose spring constant can be changed in accordance with the rotational speed at which a pilger mill stand is reciprocated.

Hereinafter, the structure of the present invention will be explained in detail with reference to the embodiment shown in FIG. Note that the same parts as in the conventional example shown in the second figure are denoted by the same reference numerals, and the explanation thereof will be omitted.

[Basic control] This example is suitable for a so-called large-sized Pilger rolling mill that cold-rolls a seamless steel pipe with a diameter of 260 mm and generates an inertia force of about 607 ON during reciprocating motion. focuses on the fact that the first-order term of the inertia of the reciprocating motion and the spring force can be well balanced, and attaches only the first-order term of the inertial force of the reciprocating motion of the pilger-mill stand 8 to the pilger-mill stand 8. In addition, the spring constant k of the coil spring 10 is changed to the optimum spring constant k according to the rotational speed ω of the crankshaft 2.

Therefore, first, assuming that the rotational speed ω of the crankshaft 2 is constant (normally rolling is carried out in such a state),
Since the first-order term of the inertia of the reciprocating motion of the pilger mill stand 8 can be balanced by the coil spring 10, M: Weight α of the pilger mill stand 8; Acceleration of displacement S of the pilger mill stand 8 X: Coil spring If the displacement amount is 10, then M×αkXx . . .■ may be used.

By the way, the approximate size of the spring constant used here is
Find it as follows. That is, in this embodiment, only the first-order term of the inertia of reciprocating motion due to crank motion is balanced and higher-order terms are ignored, so the well-known general formula expressing the inertia of reciprocating motion is expressed as R/ If L<< 1, α−−ω×x . . .■ is derived. From these ■ and formula 0, the spring constant = Mω
... (2) is obtained, and by selecting such a spring constant k, most of the inertia of the reciprocating motion of the pilger mill stand 8 can be balanced.

Next, in this embodiment, the rotational speed ω of the crankshaft 2 is changed to operate properly. For example, when rolling a large number of raw pipes in series, there is an operation in which the maximum rotational speed ω1laX is lowered to about half of that to prevent cracking. As is clear, it is necessary to change the spring constant k in accordance with the changed rotational speed ω. Therefore, in order to change the spring constant k, in FIG. 1, 2. A spring constant k that satisfies the above formula 0 is calculated by the spring constant calculating section 12, and the combination of the coil springs 10 is changed in order to obtain the spring constant k.

In order to change the combination of coil springs 10,
In the spring constant variable device 13 shown in FIG.
A connecting rod 14 connected to the mill stand 8 is connected to a guide guide 15, and the coil spring 1 is connected to the guide guide 15.
Attach 0. The coil spring 10 has a spring constant k on one side.
Four first compression coil bars with l, k2...$16
a, 16b... and similar second compression coil springs 17a, 17b... on the other side.

The guide 15 has four spring rods 18a, 18b.
... are slidably inserted through the spring rods 18, and the first and second spring receivers 19, 20 are fixed to both ends of each spring rod 18. Therefore, the first rlE compression coil spring 16 is supported by the guide 15 and the first spring receiver 19. These spring holders]9
．． 20 is pressed by first and second hydraulic cylinders 21a, 21b-122a, 22b- for controlling spring action. The first hydraulic cylinder 21 is fixed to one end plate 24 of the guide frame 23, and the second hydraulic cylinder 22 is fixed to the other end plate 25.

A liner portion 2G of the guide guide 15 is slidably guided by the guide frame 23. One end plate 24
is freely inserted through the fiJi 13 by the connecting rod 14,
The other end plate 25 is fixed.

To change the spring constant of the coil spring 10, the third illustration is set to the neutral position, and the first hydraulic cylinders 21b, 21
e and the second hydraulic cylinder 22b122C, when the pilger mill stand 8 is moved forward in the E direction in the figure, the guide guide 15 also slides in the same direction by the connecting rod 14, so that the second compression Coil springs 17b, 17c
is compressed.

Next, when the pilger mill stand 8 moves back in the direction F in the figure, the guide 15 also slides in the same direction, and the first compression coil springs 16b and 16c are compressed.

In this case, the total spring constant of the coil spring 10 is 2
+ becomes 3. Furthermore, if i+b pressure is supplied to all the first and second hydraulic cylinders 21 and 22, the first and second compression coil springs 1G and 17 will all act as springs, and the spring constant will be kl +. 2 Ten becomes 3+4,
In this case, it is necessary to balance the maximum value of the inertia force of the reciprocating motion of the pilger mill stand 8, and as mentioned above, it is necessary to select the optimum number of springs according to the rotational speed ω, so each hydraulic cylinder 21a , 21b-122a, 22b-... are turned ON by the signal calculated by the spring constant calculating section 12.
, OFF are performed, the spring constants are combined, and the spring constants are controlled to become the optimum spring constant.

In this embodiment, only the first-order term of the inertia of the reciprocating motion of the pilger mill stand 8 is reduced by the coil spring 10 through the control described above.
and the rotational speed ω of the crankshaft 2.
The optimum spring constant k of the coil spring 10 corresponds to the change in
It can be changed to

In this embodiment, the coil spring 10 is used as the spring, but the present invention is not limited to this, and a fluid spring may be used.

In summary, since the present invention employs the configuration described in the claims, the following effects are achieved.

〔Effect of the invention〕

■Compared to the conventional Pilger type rolling mill equipped with ■balancers and sector balancers, the unbalance elimination effect is the same (however, it can be reduced by 20%), but because these balancers are not present, it is possible to reduce the size and speed (e.g. , ω can be increased by 1.5 times), which not only makes maintenance easier and simplifies foundation work, but also balances the unbalanced force generated by the reciprocating motion of the pilger mill stand with spring force. Therefore, energy saving can be achieved. In other words, for example, in a large Pilger rolling mill, the inertial force reaches a maximum of 60 TOH, so a lot of external energy is required to balance this inertial force, but this external force can be covered by the elasticity of the spring. It will be done.

■ Since the spring constant of the balancing spring is changed according to the rotational speed of the rotational movement, it is possible to properly eliminate unbalance at all times (such a situation is shown in the graph in Figure 4), and it also eliminates unnecessary unbalance at low rotational speeds. Since no spring force is applied, the pilger mill stand can smoothly reciprocate at low rotational speeds.

(2) Since the inertial force is balanced by springs, it can be installed in combination with Birgal type rolling mills equipped with conventional fan-shaped balancers and (2) balancers, and in such cases, the fan-shaped balancers and V-balancers can be downsized.

■ According to the present invention, since the inertial force is balanced by a spring, there is no need for connecting rods, crank arms, crankshafts, etc. that require machining to receive such excessive force, and there is no need to increase the size, reducing costs. can be achieved.

In addition, Figure 4 shows L=4000 crane, R-720 fin, M#
The test was conducted at 35 TON, and the graph shows the amount of inertial force imbalance with the vertical axis representing the force (TON > and the horizontal axis representing the time (seconds). The figure (a) shows ω = 45 rpm, k -4
In the case of 00kg/cm x 2set (both sides), (b)
The diagram shows ω-3Orpm, k-1731g/c@X2
set (both sides) are shown. The broken line shows the amount of inertial force unbalance in the conventional example shown in FIG. 2, and the solid line shows the amount of inertial force unbalance in this embodiment. As is clear from the figure, in this embodiment the unbalance is always small. .

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the present invention, FIG. 2 is a schematic diagram of a conventional example, FIG. 3 is an enlarged view of a main part of the embodiment of FIG. 1, and FIG. 4 is a graph of a test example. 7... Pilger mill roll, 8... Pilger mill stand, lO... coil spring, k... spring constant. Agent: Patent attorney Masanobu Kato (and 1 other person)

Claims (2)

[Claims] (1) In an inertia force balance device for a Pilger rolling mill that horizontally reciprocates a Pilger mill stand equipped with a pair of Pilger mill rolls using power converted from rotational motion to reciprocating motion, the Pilger mill stand A pilger is equipped with a spring that balances only the first-order term of inertia of the reciprocating motion of the pilger mill stand, and the spring constant of the spring is changed in accordance with the rotational speed of the rotary motion. Inertial force balance device for type rolling mill. (2) The inertial force balance device for a Pilger rolling mill according to claim 1, wherein the spring is a combination coil spring, and the spring constant is changed by changing the combination.