JPH0312963B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized in that a roll housing, a work roll supported in a chock within a window of the roll housing, and a backing roll supported behind the work roll are moved relative to each other by a hydraulic pressure reduction device. is adjustable and
4 with a pressure medium cylinder that keeps the component engaged in the window and/or the roll chock open even after the rolled product has left with the work roll;
Concerning how to operate a heavy rolling mill. Quadruple rolling mills of this type are widely installed for cold rolling, where the hydraulic reduction device allows high adjustment speeds and especially high adjustment accelerations, so that not only the adjustment process but also the control process is affected. It has proven to be an excellent final control element.

A noticeable disadvantage of such rolling mill housings is that the spring constant of the housing is not constant, especially in the lower stress region, so that the adjustment device for the roll clearance in this region cannot perform the desired precise adjustment movement ( hysteresis phenomenon). This drawback becomes less noticeable during rolling with high rolling forces, ie, during strong reductions of hard sheets of large width. The lower the rolling forces that occur during operation, the more the above-mentioned interference effects are detrimental to the rolling process. Therefore, the above-mentioned effect does not appear when rolling hard aluminum alloys that require high rolling forces, but rolling soft pure aluminum becomes considerably difficult.

This invention addresses the problem of reducing not only the effects of hysteresis effects, but also the effects of uneven housing swelling, so that they no longer appear and cannot interfere with the rolling process. I left.

A typical quadruple rolling mill housing is equipped with pressure medium cylinders, which support the upper roll chock against the lower chock, and the task of which is to press the work rolls onto the respective associated hold-down rolls and to release the rolled product. The work rolls should be left open so that even after the roll is finished, the roll gap remains open and cannot be closed due to the weight of the upper roll chock. The forces required and exerted by the associated pressure medium cylinders are:
Usually about 20 to 40% of the weight of the upper roll chock
In extreme cases it exceeds 100%. Usually this so-called balancing device is constantly loaded, at least until the rolled product is pulled out and the next rolled product is bitten, and the load is maintained during rolling, for simplicity, so that the rolling force is maintained in the stand. Other balancing forces act. However, such a balancing force is very small, so that together with the low rolling force, the unstable region of the characteristic curve cannot be avoided.

On the other hand, so-called prestress rolling mills are known. In this method, a control force related to the rolling force is applied between the chokes of the hold-down rolls, so that the sum of the rolling force and the additional control force is constant. In this way, a constant force is applied to the rolling stand, causing a constant elongation of the stand, eliminating the difference in elongation, and obtaining the thickness of the rolled product. However, such control of the roll gap does not eliminate the hysteresis effect described above. that's why,
The rolling force is measured using a measuring device installed on each chock, and hysteresis is predicted by correlating it with the movement of the chock. It is also not possible to remove an adjusting or prestressing device, which consists of a threaded spindle and a nut screwed into it, if provided between the chokes of the hold-down roll. In this case, the relative position of the hold-down roll chock, and this relative positioning, on the one hand depends on the load and, on the other hand, is also subject to a hysteresis effect, since it requires a free adjustment of the load fluctuations of the chock.

In the present invention, instead of the balancing device, and if necessary in addition to the balancing device, a pressure medium cylinder is provided which provides an additional force, so that a sufficiently large constant force can be applied at least during rolling, preferably at least during rolling. Operate during the entire operating period. The acting force in this case is 15-40% of the maximum rolling force, preferably 20-30%
%. In this way, even when rolling a rolled product that requires only a small rolling force with hysteresis, it is possible to go beyond the unstable part of the characteristic curve and roll in the unique straight part of the characteristic curve.

The ram, which is supported by a pressure medium cylinder, is preferably guided in the chock of the work roll. However, it is also possible to be mounted in an element inserted into the window of the housing. If the pressure medium cylinder is connected in parallel to the pressure tank, then
A uniform loading of the pressure medium cylinder is obtained.

The features of the invention will be explained in detail with reference to the following description of embodiments and the drawings illustrating them.

FIG. 1 shows a side view of a quadruple rolling mill to which the operating method according to the invention is applied, in which the components of the housing 1 are generally shown in section.

Key adjustment device 2 in the lower side beam of the housing 1
is provided, with the help of which the upper surface line of the lower work roll is adjustable in the height of the rolling pass line. The key adjustment device 2 also includes a pressure measuring cell 3
Supports the chock 4 of the unfavorable roll through the
Above this, chock 5 and 6 of the lower and upper work rolls and chock 7 of the upper backing roll are shown. Chocks 4 and 7 of the hold-down roll are guided by wear plates (not shown) arranged in the housing window, while jocks 5 and 6 are guided by wear plates which are inserted into the window section. It is supported by a bracket 8, which is also not shown, and is arranged in front of the front face of the bracket 8, which is also not shown and reaches the side of the chock.

Bracket 8 comprises hydraulic cylinders 9 and 10 whose piston rods are connected to work roll chokes 5 and 6.
It is intended to support the lateral processes of and open them. The hold roll chock 4 and 7 are equipped with hydraulic cylinders 11 and 12 whose piston rods support the respective opposite walls of the work roll chock 5 or 6. A hydraulic pressure adjusting cylinder 1 is installed between the upper horizontal beam of the housing 1 and the chock 7.
3 is illustrated. a rear housing 20;
A counterbalance cylinder 14 is arranged between the housing 1 and the housing 1, which is shown broken at the upper crossbeam, the cylinder having a spar 1 with a tension bar at each end.
5. The pull rod ends in a hook 16 which grips the upper chock 7 from behind and pulls it towards the loading space of the adjusting cylinder 13. The balancing cylinder 14 thereby supports the weight of the upper stay roll chock 7 and presses it against the adjusting cylinder 13, so that not only the balance of the upper stay roll chock but also a positive setting for the adjusting cylinder 13 is achieved.
The hydraulic cylinder 10 is connected to the chock 6 of the upper work roll.
and at the same time its cylinder cooperates with hydraulic cylinders 11 and 12. By means of the hydraulic cylinders 9 to 12 an additional force can be created on the chock of the work roll, which force can change the bending moment of the chock and thus its deflection.

A pressure medium cylinder 17 is additionally provided in the chock 4 of the lower backing roll, the piston rod of which carries a ram 19 guided in a bearing 18 of the bracket 8, the front face of which is located in the upper backing roll. Support Chiyotsuku 7 from behind.

During the operation of a normal quadruple rolling mill, especially when rolling with low rolling forces, for example when rolling pure aluminum or synthetic resin foils, the above-mentioned interference effects occur and have a serious influence. According to our view, the hysteresis effect is already present in adjustment cylinder 1.
It is caused by No. 3 Patsukin. The friction force generated by the sealing gasket is in the opposite direction to the adjustment direction at that time, and the difference in the force with which the adjustment action is released is the static friction of the sealing gasket, which is almost constant when using a Teflon gasket, for example. An adjusting action can only be carried out when , which is furthermore determined to be independent of the load, is exceeded. The support of the chock in the housing window consists of several more or less flat components (e.g. key adjustment device 2, pressure measuring cell 3,
In addition, this is done via intervening spacing plates, etc.). According to our opinion, elements which are generally not completely flat or rectangular are supported by only one, two or three regions (sections). Then, when large loads or high rolling forces occur, the above-mentioned element first deforms elastically and then supports on a large surface, after which its deformation follows Hook's law. Thus, in the range of low loads on the housing, the elastically deforming element influences its spring constant. This deformation is substantially completed at high loads. This is the reason why the characteristic curve of the stand is not only weaker in the low load region than in the high load region, but also unstable, uncertain, and unambiguous in the low load region.

A characteristic curve of the housing swelling of the housing illustrated in FIG. 1 is shown in FIG. 2, which shows the results of the aforementioned effects. The ordinate 21 shows the current housing load, in particular the rolling force P, while the abscissa 22 shows the housing swelling f.
The characteristic curve 23 of the housing runs approximately linearly. However, in the region below it, the line deviates from the straight dotted line 24 and moves towards the zero point within a wide dispersion area.

The housing is operated within the linear region of the characteristic curve 23 as long as the main part of the maximum rolling force 26 is applied. When rolling with very low rolling forces,
For example, when rolling pure aluminum, the dispersion range is 2.
5, the relationship between housing load and housing swelling is no longer unambiguous and the correlation becomes unstable. Dispersion zones 25 should be avoided, since a clear and reproducible relationship must prevail during rolling. This dispersion region extends to approximately 30 to 35% of the maximum rolling force. The actual housing stress results from the sum of the forces acting on the roll gap. That means that the housing stress usually results from the sum of the rolling forces as well as the balancing forces. Therefore, the starting point of the working area of the housing is lifted from the origin of the ordinate by a proportionate force. In the case of small rolling forces, this balancing force is not sufficient to bring the housing stresses out of the distribution area. Therefore, according to the invention, a force is introduced by the pressure medium cylinder 17, which force acts between the chock 4 and 7 of the hold-down roll and with it practically the roll nip, and the entire housing becomes additionally is loaded. The force exerted by this pressure medium cylinder 17, together with the counterbalancing force, causes the operating point of the housing to be moved beyond the distribution area 25 even during small rolling forces to the characteristic curve 2.
It is distributed to lift up to the linear region of 3.

For example, the roll housing shown in Figure 1 is
Designed for a maximum rolling force of 1500t. However, this load is only reached when rolling high-alloy aluminum or steel. For example, rolling pure aluminum requires only 100 tons of rolling force.

The weight of the upper roll chock 7 reaches approximately 60 tons,
The balancing cylinder 14 is capable of generating a force of 100 t, and the pressure medium cylinders 9 to 12
The force generated by is added. The counterbalancing force is therefore already above the usual standard of 120% to 140% of the weight of the upper chock. Pressure medium cylinder 17
additionally generates a force acting on the roll gap and being applied to the housing, in particular its chock and reduction force regulator, which force can reach 300 t, thereby far exceeding the normal counterbalancing force. exceeds. During rolling with high rolling forces, the pressure medium cylinder 17 is sufficiently or completely unloaded so that no additional housing stresses occur. However, only low rolling forces are required for rolling soft materials, and the pressure medium cylinder is effectively applied between 15 and 40% of the maximum rolling force so that the housing load during rolling is within the linear region of the characteristic curve 23. A constant load is applied to the The forces acting on the roll housing are now so high despite the small rolling forces that the usual attachments such as spacing plates and spacing blocks, pressure measuring cells, etc. are reliably supported rigidly and have hysteresis phenomena. No deterioration of the spring characteristic curve due to the formation of the dispersion region 25 occurs. In addition, the overall housing load, ie the load on the adjusting cylinder 13 which is intended to absorb the additional forces occurring in addition to the rolling forces, is significantly increased;
On the other hand, not only the sealing seal static friction but also the sliding friction maintains its value. Therefore, the ratio of the magnitude of the adjustment force to the magnitude of the frictional force is increased, so
These frictional forces are no longer significant, and the aforementioned hysteresis phenomenon no longer occurs when operating with low rolling forces.

It is known from German Patent No. 644 957 to provide pressure medium cylinders in the roll nip, which are actuated by a control device or serve as measuring instruments themselves. For the same purpose of compensating rolling force fluctuations, German Patent Application No. 1294317 describes a pressure medium cylinder which is loaded in response to rolling force fluctuations. The pressure medium cylinder proposed according to the invention is not inserted for control purposes, but rather the forces applied to the roll housing, its rolling device and elements control the working area during rolling in the linear region of the characteristic curve 23. When working with low rolling forces, these It serves only the purpose of increasing the rolling force additively and constantly.

In the exemplary embodiment, separate pressure medium cylinders are provided for balancing and for prestressing the roll housing. However, there is the possibility of involving a pressure medium cylinder not only for adjusting the prestressing but also for balancing the hold-down roll chock, and for the adjustment process an identical pressure medium cylinder is additionally installed, Thereby, a constant pressure component corresponding to 15 to 40% of the maximum rolling force can act as a prestress on the housing, and by superimposing a variable pressure component onto this, it is also possible to produce the desired adjustment process.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view of a rolling mill roll housing used to carry out the operating method according to the present invention. FIG. 2 is a spring characteristic curve of the roll housing of FIG. 1, 20...roll housing, 4, 5, 6, 7
...Chick, 8...Bracket, 13...Adjustment (down) cylinder, 14...Balance cylinder, 17...
Pressure medium cylinder, 19...ram, 20...roll housing.

Claims (1)

[Scope of Claims] 1. A roll housing, a work roll supported by each chock in a window thereof, and a backing roll supporting these from behind can be pressed in mutual directions by a hydraulic pressure reduction device, In addition, each component and/or the roll chock fitted into the window is provided with a pressure medium cylinder which keeps both work rolls open even after the material to be rolled has passed.
Each chock of the lower backing roll is further equipped with another pressure medium cylinder. In the method of operating the quadruple rolling mill, each pressure medium cylinder 17 provided in the chock 4 of the lower support roll is directly or indirectly supporting the chock 7 of the upper backing roll and applying the maximum rolling force of 15 to these pressure medium cylinders 17.
During rolling with a small rolling force of less than A method for operating a quadruple rolling mill, characterized in that the addition is carried out so as to produce the desired result.