JPS62244502A - Inertial force balancing device for pilger type rolling mill - Google Patents

Abstract

PURPOSE:To reduce the size of a rolling mill and to speed up rolling by providing coil springs which balance the linear term of inertial force and mounting mass unbalancers which balance the quadratic term to rotating bodies which are forcibly rotated. CONSTITUTION:Plural sets of the coil springs 10 which can adjust spring constants to meet the rotating speed of a crank shaft 2 are provided and the mass unbalancers 14, 14' which balance the quadratic term of the inertial force of reciprocating motion are mounted to the rotating bodies 13, 13'. The coil springs 10 change the spring constants of the coil springs by means of hydraulic cylinders built thereto so as to meet the change of the rotating speed omega of the crank shaft 2. The balancers 14, 14' of a pair of the upper and lower rotating bodies 13, 13' relative to a stand 8 balance the quadratic term of the inertial force according to the rotating speed omega detected by a detector 11. Since there are no balance weights, the reduction of size of the rolling mill 8 and the speeding up of the rolling are attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises:
This invention relates to an inertial force balance device for a Pilger rolling mill that manufactures seamless steel pipes, etc.

[Conventional technology and its problems]

Generally, a Pilger type rolling mill equipped with a Pilger mill roll has a special caliper between a pair of Pilger mill rolls and a mandrel rod, as shown in Japanese Patent Publication No. 51-4.3472. The raw pipe is rolled to produce seamless steel pipe. Its structure and operation will be explained with reference to a schematic diagram of a conventional example shown in FIG. and a connecting rod 6 for a V balancer are connected, and a pair of pilger mill stands 8 are connected to the tip of the connecting rod 5, and a V balancer 9 is suspended from the tip of the connecting rod 6 for the 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 Birgal mill roll 7 rotates via a rank and pinion (not shown) to roll 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 size. 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 and in contact with the rolls 7, but moves forward as soon as the raw tube is freed from the rolls 7.

As described above, the conventional Pilger type rolling mill that has been put into practical use employs a crank mechanism to reciprocate the Pilger mill stand 8 on which the Pilger mill roll 7 is attached with great force. Unbalance occurs due to the inertial force of the reciprocating motion induced by the motion and the couple due to the inertial force. In order to eliminate this unbalance, the fan-shaped balancer 4 and the V-balancer 9 are provided as described above.

However, in the conventional Pilger type rolling mill, the following disadvantages occur 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 ■balancer 9, the unbalance of the first-order term (the first-order term in the general formula representing the well-known reciprocating inertia force; the same applies hereinafter) based on the rotational speed ω of the crankshaft 2 is eliminated. However, the imbalance of higher-order terms cannot be eliminated. In order to reduce the unbalance of the higher-order terms, the ratio of the length R of the crank arm 3 to the length of the connecting rod 5 must be reduced, which increases the length of the connecting rod 5 and increases the The whole becomes larger. 3) Since the unbalance of higher-order terms based on the rotational speed ω of the crankshaft 2 cannot be eliminated, the connecting rod 5, the crankshaft 2, etc. inherently receive a large inertial force proportional to the square of ω. If the speed increases, a structure that can withstand this inertial force becomes unrealistic, and therefore there is a limit to how high the speed can be increased.

4) Since the V balancer 9 is provided, for example, φ260m1
The pilger mill rolling mill for cold rolling steel pipes requires foundation work approximately 8 meters deep, which in turn makes maintenance around the balancer 9 difficult.

On the other hand, in a pilger type 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 a piston rod of an air cylinder is connected to the pilger mill stand, and compressed air is supplied to the air cylinder to balance the inertia of the reciprocating motion of the pilger mill stand. (See British Patent No. 1355733).

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

[Means for solving problems]

Therefore, the present invention was created to solve all of the problems of the prior art at once, namely, to balance the first-order term of inertia of the reciprocating motion of the pilger mill stand on the pilger mill stand. A coil spring is attached, and the spring constant of the coil spring can be changed according to the rotational speed for reciprocating the pilger mill stand, and a mass unbalancer that is forcibly rotated is attached to the pilger mill stand. The object of the present invention is to provide an inertial force balance device for a Pilger type rolling mill that balances the quadratic term of the inertial force of the reciprocating motion.

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.

This example is suitable for a so-called large Pilger type rolling mill that cold-rolls a seamless steel pipe of φ2 G On+ and generates a jR force of about 60 TON in the Note IM motion, but its outline is as follows. The first-order term of the inertial force of Pilger mill stand 8 is
Focusing on the fact that it almost matches the linear characteristics of the coil spring 10,
In addition to balancing these, multiple coil springs
A rotating body that changes the total spring constant k of O to the optimum spring constant k according to the rotational speed of the crankshaft 2, and forcibly rotates the quadratic term of the inertia force of the reciprocating motion. Mass unbalancer 14.14' attached to 13.13
It is a matter of balance.

Therefore, first, the rotational speed ω of the crankshaft 2 is constant (usually
When rolling is carried out in such a state, it is only necessary to balance the first-order term of inertia of the reciprocating motion of the pilger mill stand 8 with the coil spring 10, so M: weight of the pilger mill stand 8 α: Acceleration of displacement of pilger mill stand 8 X: Displacement amount of length of coil spring 10, then M×α−1cXx . . .

By the way, the size of the spring constant used here balances only the - next term in the well-known general formula that expresses the inertia force of reciprocating motion due to crank motion, so αζ-ω×x ・- −■ is led. From these formulas ■ and ■, the spring constant is = Mω2
. . . The coil spring 10 used therein can be determined.

Next, when operating the crankshaft 2 at a different rotational speed ω, for example, when rolling a joint part of a blank pipe, the maximum rotational speed ωmax is reduced to about half of the maximum rotational speed ωmax to prevent cracking. There is an operating method, but when performing such an operation, as is clear from the above equation 0, it is necessary to change the spring constant k in accordance with the changed rotational speed ω. In the figure,
According to the rotational speed ω detected by the rotational speed detector 11 attached to the crankshaft 2 driven by the main motor,
A spring constant k that satisfies the above equation 0 is calculated by the spring constant calculating section 12, and in order to obtain the predetermined spring constant k, one of the coil springs 10 configured in parallel is caused to act as a spring. That is, the effective number of springs is changed.

Here, to change the total spring constant k,
This is done using the spring constant variable device shown in FIG.

That is, in the same figure, the above and Luger mill stand 8
The connecting rod 17 connected to the connecting rod 17 is connected to a guide guide 18, and the coil spring 10 is attached to the guide guide 18.

The coil spring 10 includes four first compression coil springs 19a, 19b, . . . with spring constants kl, k2, .
It is composed of 0a, 20b, and so on. Four spring rods 21a, 21b, . Therefore, the first compression coil spring 19 is supported by the guide 18 and the first spring receiver 22. These first and second spring receivers 2
2.23 are pressed by first and second hydraulic cylinders 24a, 24b-25a, 25b for spring action control. The first hydraulic cylinder 24 is connected to a second hydraulic cylinder 25 on one end plate 27 of the guide frame 26.
is fixed to the other end plate 28. The guide frame 2
6, a liner portion 29 of the guide 18 is slidably guided. The connecting rod 17 is slidably inserted through one end plate 27, and the piston rod 12 of the hydraulic cylinder 11 is connected to the other end plate 28.

To change the spring constant k of the coil spring 10,
The third illustrated position is the neutral position, and as illustrated, the first hydraulic cylinders 24b, 24C and the second hydraulic cylinder 25
b. When hydraulic pressure is supplied to 25C and the pilger mill stand 8 moves forward in the E direction in the figure, the guide guide 1B also slides in the same direction by the connecting rod 17, so the second compression coil spring 20b.

20c is compressed. Next, Pilger Mill Stand 8
When the guide moves back in the direction F in the figure, the guide 18 also slides in the same direction, and the first compression coil springs 19b and 19C are compressed. Therefore, the total spring constant of the compression coil spring 19.20 is 20.3. Furthermore, if hydraulic pressure is supplied to all the first and second hydraulic cylinders 24.25, the first and second compression coil springs 19.20 will all act as springs, and the spring constant will be = kl + and 2 +. 3+ becomes 4. In this case, the maximum value of the inertial force of the reciprocating movement of the pilger mill stand 8 is balanced.

As mentioned above, since it is necessary to select the optimum spring constant according to the rotational speed ω, each hydraulic cylinder 24a24b...
, 25a, 25b, . . . are turned ON and OFF according to the signal calculated by the spring constant calculation section 12, and the spring constants are combined and controlled so that the optimum spring constant is obtained.

Next, in this embodiment, the quadratic term in the general expression of the inertia force of the reciprocating motion of the pilger mill stand 8 is replaced by a mass unbalancer 14.
Balance by 14°. In other words, the inertial force F of the reciprocating motion of the pilger mill stand 8 is calculated from the well-known general formula as follows, where t is time: is Fs #kx
=kR(cos ωt +f)/Acos2ωt)
...■ The horizontal force FB due to the mass unbalancer 14.14" is FB = (mr (2ω) cos2ωt) X
2 ・"■However, ρ-R/L m: Weight of mass unbalancer 14 r: Unbalance radius, so in these formulas, mr can be found from the ■ formula of ■-■]-■ ...■ It will be done.

Therefore, from equations (1) and (2), the weight m and unbalance radius r of the mass unbalancer 14.14° for balancing are 2L.Then, the obtained m-r is mounted on the pilger mill stand 8. That is, a mass unbalancer 14.14" is attached to a pair of upper and lower rotating bodies 13.13 degrees rotating in opposite directions on the pilger mill stand 8, and a gear 15.15" is attached between these rotating bodies 13.13 degrees. The lower rotating body 13 is rotated by an auxiliary motor 30 via a universal spline 16 and a speed reducer 29.

Therefore, in accordance with the rotational speed ω detected by the rotational speed detector 11, the rotational speed command calculation unit 31 calculates the rotational speed command so that ω' = 2ω, and supplies it to the amplifier 32 to control the auxiliary motor 30.

In this case, a rotation angle detector 33 attached to the crankshaft 2
The phase detected by the above and the phase detected by the rotation angle detector 34 attached to the shaft of the upper rotating body 13'' are measured by a rotation angle calculation phase shift correction command tuning circuit 35, and the deviation between the two is measured. The signal is then applied to the amplifier 32 to control the auxiliary motor 30, thereby eliminating phase shift and improving balance accuracy.

In this embodiment, by the control described above, the first-order term of the inertia force of the reciprocating motion of the pilger mill stand 8 is balanced by the coil spring 10, and the second-order term is attached to the pilger mill stand 8 to force A pair of rotating bodies 13 that rotate
．． Balanced by a mass unbalancer 14.14° equipped with a 13"
can be changed, and in response to this change, the spring constant k of the coil spring 1° is optimized, and of course, the rotating body 13
．． A rotational speed ω'' of 13° can also be optimized.

Note that this example uses a so-called large-sized Pilga rolling mill (
Cold Reducing Tube Mill)
However, the present invention is of course not limited to this, and can be applied to, for example, a pilger-type rolling mill for steel plates and steel bars. Further, in this embodiment, the rotating body 13
Although the auxiliary motor 18 is used to drive the motor, it may also be driven by a gear ring or the like from the crankshaft 2.

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 rolling mill equipped with ■balancers and sector balancers, there is no balance weight, so it is smaller, faster (for example, ω can be sped up by 1.5 times), and easier to maintain. This not only makes it possible to reduce the amount of energy and make foundation work easier, but also to save energy because the unbalanced force caused by the reciprocating motion of the pilger mill stand is balanced by the spring force of the coil spring.

That is, for example, in a large pilger rolling mill, the inertial force reaches a maximum of 60 TON, so a lot of external energy is required to balance the maximum value of the inertial force, but this external force is due to the elasticity of the spring. It will be covered by

■ Since the spring constant of the coil spring to be balanced is changed according to the rotational speed of the rotational motion, unbalance can be properly eliminated at all times, and undue spring force that occurs at low rotational speeds does not act, so it can be used at low rotational speeds. The Pilger
The reciprocating motion of the mill stand can operate smoothly.

■ Since the quadratic term of the inertial force is balanced by a mass unbalancer using a rotating body that is forcibly driven, in combination with the above (■), the inertial force of the reciprocating motion of the pilger mill stand can be almost balanced. Of course, the external force for balancing only the quadratic term does not require that much external energy, and can also be well adapted to changes in the rotational speed of the crankshaft.

(2) The speed can be increased by the above (2), and stable operation can be achieved even in the high speed range.

■ Since the quadratic terms are balanced, there is no need for the connecting rod, crank arm, and crankshaft, which are made of high-quality materials that require machining, to be subjected to excessive forces, and as a result,
Can be made smaller. Therefore, significant cost reductions can be achieved. In addition to this, for example, the foundation bolts (
This is required for any pilger mill stand) is -
In the case of the conventional example in which only the next term is eliminated, at least the inertia force of the quadratic term must be supported, so if the speed is increased, this must be strengthened, but according to the present invention, The quadratic term is balanced, and the foundation bolt only needs to support the rolling horizontal reaction force (approximately 10% of the rolling force), and this horizontal reaction force has almost no relation to the rotation speed, so even if the speed is increased. , it does not affect the foundation bolts at all and can be used at low rotational speeds. In other words, according to the present invention, even if the inertia of the reciprocating motion of the pilger mill stand increases due to the increased speed, the inertia can be supported via springs in the machine frame that does not require machining. , does not affect foundation bolts.

[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, and FIG. 3 is a diagram of main parts of an embodiment of the present invention. 7... Pilger mill roll, 8... Pilger mill stand, 10... Coil spring, 13... Rotating body, 1
4...Mass imbalancer.

Claims (1)

[Scope of Claims] An inertial 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, comprising: A coil spring is attached to the Pilger Mill stand to balance the first order term of the inertia of the reciprocating motion of the Pilger Mill stand, and a rotation forced to rotate by an external force balances the second order term of the inertia of the reciprocating motion. An inertial force balance device for a Pilger type rolling mill, in which a mass unbalancer is attached to the body, and the spring constant of the coil spring and the rotational speed of the rotating body can be changed according to the rotational speed for reciprocating the body. .