JPS62244503A - Inertial force balancing device for pilger type rolling mill - Google Patents

Abstract

PURPOSE:To reduce the size of a rolling mill by providing coil springs which balance the linear term of inertial force and disposing mass unbalancers which can vary spring constants and further balance the quadratic term of a crank shaft. CONSTITUTION:A spring constant varying device 16 having the plural coil springs 10 is provided and is connected to a stand 8. Revolving shafts 14, 15 are provided to a frame in which the crank shaft 2 is inserted. The mass unbalancers 13, 13' are respectively disposed to the shaft ends. The device 16 balances the linear term of the inertial force of the stand 8 by adjusting the total spring constant of the coil springs 10 to the value optimum for the rotating speed omega of the crank shaft 2 and the mass unbalancers 13, 13' balance the quadratic term of the inertial force. The balance weights is eliminated, the size of the stand 8 is reduced and since the balancing is executed by the coil spring force, the economization on energy is contrived.

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 with a schematic diagram of a 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 connecting rod 5 and a connecting rod 6 for a V balancer are respectively attached to the crank arm 3. A pilger mill stand 8 equipped with a pair of pilger mill rolls 7.7 is connected to the tip of the connecting rod 5, and a 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 movement, the pilger mill roller rotates via a rank and pinion (not shown) and rolls the raw pipe. In other words, when the Birker 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 when 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 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 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 reciprocating inertial force induced by the crank motion and the couple due to the inertial force. In order to eliminate this unbalance, the fan-shaped balancer 4 and the (1) balancer 9 are provided as described above.

However, in the conventional pilger rolling mill, the following problems arise due to the installation of the fan-shaped balancer 4 and the 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 balancer 9, it is possible to eliminate the unbalance of the first-order term of the rotational speed ω of the crankshaft 2 (the first-order term in the well-known formula representing the reciprocating inertia force; the same applies hereinafter). 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, crankshaft 2, etc. naturally receive a large inertial force proportional to the square of ω, resulting in high speed. If the
Therefore, there is a limit to speeding up. 4) V balancer 9
Therefore, for example, a pilger mill for cold rolling steel pipes of 260 m in diameter requires foundation work approximately 8 m deep, which in turn makes maintenance around the balancer 9 difficult.

On the other hand, in a pilger set 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 mass amparancer is provided in which a plurality of coil springs are mounted, the total spring constant of the coil springs can be changed according to the rotational speed of a crankshaft for reciprocating the pilger mill stand, and the mass amparancer is mounted on the crankshaft. Another object of the present invention is to provide an inertia force balance device for a pilger rolling mill that balances the quadratic term of the inertia 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 those in the conventional example shown in FIG.

In this example, a seamless steel pipe with a diameter of 260 fl is cold rolled,
It is suitable for a so-called large pilger set rolling mill that generates an inertial force of about 607 ON during reciprocating motion. Focusing on the fact that they almost match, we balanced them, changed the total spring constant k of the plurality of coil springs 10 to the optimum spring constant k according to the rotational speed of the crankshaft 2, and The quadratic term of the inertial force is applied to a mass unbalancer 13.
It is balanced at 13゛.

Therefore, first, the rotational speed ω of the crankshaft 2 is constant (generally,
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: displacement of pilger mill stand 8×acceleration

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

Next, when operating by changing the rotational speed ω of the crankshaft 2, for example, when rolling a joint part of a raw pipe, the maximum rotational speed ωmax is reduced to about half of the maximum rotational speed ωmax to prevent cracking. There is a method, but when performing such operation, it is necessary to change the spring constant k according to the changed rotational speed ω, as is clear from the above equation 0. In, depending on the rotational speed ω detected by the rotational speed detector and the rotational angle detector 11 mounted on the crankshaft 2 driven by the main motor, a spring constant k that satisfies the above equation 0 is determined.
In order to calculate the predetermined spring constant k by using the spring constant calculating section 12, one of the plurality of coil springs 10 arranged in parallel is caused to act as a spring, and the effective number of springs is selected.

That is, in the spring quantity variable device 16 shown in FIG. 3, the connecting rod 17 connected to the pilger mill stand 8
is connected to a guide 18, and the coil spring 10 is attached to the guide 18.

The coil spring IO has four first compression coil springs 19a, 19b, . . . with spring constants kl, k2, .
It is composed of compression coil springs 20a, 20b, . . . . Four spring rods 21a, 2 are attached to the guide die 18.
1b... are slidably inserted thereinto, and the first and second spring receivers 22, 23 are fixed to both ends of each spring rod 21. Therefore, the first compression coil spring 19
and the first spring receiver 22. These first and second spring receivers 22,23 are the first spring receivers 22,23 for controlling the spring action.
and second hydraulic cylinders 24a, 24b..., 2
5a, 25b, etc. are pressed. The first hydraulic cylinder 24 is fixed to one end plate 29 of the guide frame 28, and the second hydraulic cylinder 25 is fixed to the other end plate 30. The guide frame 28 is connected to the guide guide 18.
The liner portion 31 of the liner is slidably guided.

The connecting rod 17 is slidably inserted through one end plate 29, and the other end plate 30 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 24b, 24
c and the second hydraulic cylinders 25b and 25c, and when the pilger mill stand 8 is moved forward in the direction E in the figure, the guide guide 18 is also slid in the same direction by the connecting rod 17, so that the second The compression coil springs 20b, 20C are compressed.

Next, when the pilger mill stand 8 moves back in the direction F in the figure, the guide 18 also slides in the same direction, and the total spring constant of the first compression coil spring 10 becomes 2 = 2 + 3
becomes. In addition, all the first and second hydraulic cylinders 2
When hydraulic pressure is supplied to 4.25, the first and second compression coil springs 19.20 act as springs, and their spring constants are = kl + 2 + 3 + 4, in this case. is balanced with the maximum value of the inertia of the reciprocating motion of the pilger mill stand 8. Moreover, as mentioned above, since it is necessary to select the optimum spring constant according to the rotational speed ω, each hydraulic cylinder 24a, 24b..., 25a, 25b-
. . are turned ON and OFF according to the signal calculated by the spring constant calculating 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 inertial force of the reciprocating motion of the pilger mill stand 8 is balanced by a mass unbalancer 13.13 degrees attached to the crankshaft 2. That is, as is well known, the inertia force FM of the reciprocating motion of the pilger mill stand 8 is calculated from the general formula as follows, where t is time, FM = MRω(cosωt+ρcos2ω
t)...■The spring force Fs of the coil spring 10 is Fs #kx =kR(cos art+ρ/4cos
2ωt)...■ The horizontal force FB caused by the mass unbalancer 13 is FB
= (mr (2ω)”cos2ωt) X 2
...■However, ρ-R/L m: Weight of mass unbalancer 13 r: Unbalance radius, so in these formulas, ■-■+■ ...■, m
r is calculated.

That is, from equations (1) and (2), the weight m and unbalance radius r of the mass unbalancer 13 for balancing are: 2L Then, the obtained mr is mounted on the crankshaft 2. That is, in FIG. 4, mass unbalancer 13.13
The rotating shafts 14, 15 are rotatably supported by the frame 32 through which the crankshaft 2 is inserted. In the figure, lower rotation axis 1
A small diameter gear 33 is fixed to the other end of the small diameter gear 3.
3 is rotated by a first gear 35 fixed to the crankshaft 2 via an idle gear 34. Here, the gear ratio between the first gear 35 and the small diameter gear 33 is 2/1. The upper rotating shaft 15 has an intermediate gear 36 fixed to its other end, and the intermediate gear 36 is rotated by a second gear 37 fixed to the crankshaft 2 . Here, the gear ratio between the second gear 37 and the medium gear 36 is 2/1. Therefore, the rotating shafts 14,15 rotate in opposite directions and at twice the rotational speed of the crankshaft 2.

Note that this embodiment uses a so-called large-sized pilger set rolling mill, but the present invention is not limited thereto, and can also be applied to, for example, a pilger set rolling mill for steel plates and steel bars.

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 water and make foundation work easier, but also to save energy because the unbalance caused by the reciprocating motion of the pilger mill stand is balanced by the force of the coil spring. That is, for example, in a large pilger rolling mill, the inertial force reaches up to 60 TON, so a lot of external energy is required to balance this inertial force, but this external force is covered by the elasticity of the spring. .

■ Since the spring constant of the balanced coil spring is changed according to the rotation speed of the crankshaft, it is possible to properly eliminate unbalance at all times, and since there is no excessive spring force that occurs at low rotation speeds, it is The reciprocating movement of the pilger mill stand can operate smoothly, improving the quality of rolled products.

■ Only the quadratic term of the inertial force is balanced by the mass unbalancer attached to the crankshaft, so the mass unbalancer can be made smaller.
Since the inertia of the reciprocating motion of the mill stand can be almost balanced, high speeds can be achieved, and stable operation can be achieved even in the high speed range.

■ According to the present invention, since the quadratic term is balanced,
There is no need for the connecting rod, crank arm, and crankshaft, which are made of high-quality materials and require machining, to be subjected to excessive force, and as a result, there is no need to increase the size, resulting in significant cost reductions. In addition to this, for example,
The foundation bolts of the housing for storing the pilger mill stand (this is required for any pilger mill stand) are: - In the case of the conventional example, which only eliminates the following items:
Since the inertial force of the second-order term had to be supported at least, higher speeds required stronger foundation bolts. However, according to the present invention, since the quadratic term is also balanced, the foundation bolt only needs to support the rolling horizontal reaction force, and since this rolling horizontal reaction force is almost unrelated to the rotation speed, it is possible to increase the speed. does not affect the foundation bolts and does not need to be changed. That is, according to the present invention, the inertia force corresponding to the increased speed is supported by the machine frame which is not particularly machined via the hydraulic cylinder, and does not affect the 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, FIG. 3 is a diagram of a main part of FIG. 1, and FIG. 4 is a diagram of another main part of FIG. 7... Pilger mill roll, 8... Pilger mill stand, 10... Coil spring, 13.13°... Mass unbalancer.

Claims (1)

[Scope of Claim] In an inertia force balance device for a Pilger rolling mill in which a Pilger mill stand equipped with a pair of Pilger mill rolls is reciprocated horizontally by a crankshaft, the A coil spring is installed to balance the first-order term of the inertial force of the reciprocating motion of the Garmil stand, and a mass unbalancer is installed on the crankshaft to balance the second-order term of the inertial force of the reciprocating motion, and An inertial force balance device for a Pilger type rolling mill, in which the spring constant of the coil spring can be changed according to the rotational speed of the crankshaft.