JPH0811251B2 - Overload prevention device in cold roll forming - Google Patents

Description

The present invention relates to a device for preventing an excessive load from being applied to a roll chock during cold roll forming of an intermediate product such as a shaped steel, especially an intermediate product having a large thickness variation in hot rolling.

The applicant previously manufactured a channel steel having a parallel flange portion and a flat web portion, in a hot rolling process, a pair of flange portions are each inclined outward with respect to a perpendicular line,
In addition, the web portion is formed into a convex shape, the cross section thereof is formed into a W shape, and an intermediate product in which the thickness of the flange portion and the web portion is almost the same as the product dimension is formed. We applied for a manufacturing method that flattens the convex-shaped web portion of the intermediate product.

In the cold roll forming, in order to flatten the convex-shaped web portion, the roll gap is previously set to the same gap as the product thickness of the channel steel, and the roll chock supporting the cold forming roll shaft is screwed. The cold roll forming is performed by applying a resultant force of a pressing mechanism that flattens the convex web portion and a force that opposes the bending in the longitudinal direction that occurs when the web portion is flattened. .

However, the thickness of the web portion of the intermediate product having a W-shaped cross section that has been hot rolled has a slight variation, and the roll gap is enlarged during cold roll forming of the web portion having a large thickness. As described above, the roll chock supporting the roll shaft is provided with a roll gap corresponding to the target thickness by the screw reduction mechanism, and the material having a larger wall thickness than the target enters the roll gap, thereby supporting the roll chock portion and the roll chock. There is a problem that a large load is applied to the stand, and the bearings forming the screw rolling mechanism and the roll chock are damaged.

On the other hand, when an excessive load is generated due to the thickness variation of the web portion, a method of increasing the rigidity of the stand or roll so as to counter the thickness variation or to absorb these loads, a load cell for detecting the load, There is a method of providing a reduction mechanism or the like composed of an electro-hydraulic servo system, but in the former case, the equipment becomes large, and in the latter case, the equipment becomes expensive, so that a suitable apparatus capable of coping with the thickness variation of the web part is There wasn't.

The present invention has been made in view of the above drawbacks of the prior art,
Fluctuations in the thickness of the web of channel steel, biting of material,
Even if an excessive load is generated, such as when biting through, it absorbs the load by an inexpensive method, and therefore, in the device of the present invention, the rolling mill stand having a low rigidity can be used.

According to the present invention, a plurality of sets of cold forming rolls arranged in parallel with each other, at least one of which is rotated by a drive device, roll shafts formed at both ends of the cold forming rolls, and the roll shafts being rotatable. A roll chock that has a roller bearing inside, and a screw reduction mechanism that applies a pressing force to the roll chock that supports the upper roll of the cold forming rolls to position the roll gap, and to cope with fluctuations in web thickness. Adopts a hydraulically driven holding mechanism that does not include the electro-hydraulic servo for controlling the roll interval, and forms a closed loop with the oil that operates the hydraulic cylinder of this holding mechanism, so that the hydraulic pressure in the hydraulic circuit is always constant during normal operation. When the work material is larger than the predetermined thickness and is likely to be overloaded during molding, An accumulator that absorbs changes in hydraulic pressure above a certain level is provided to keep the pressure constant, and even if there is slight variation in the wall thickness of the web, the accumulator can absorb the increase in hydraulic pressure in the hydraulic cylinder. It is possible to prevent an excessive load from being applied to the roll chock or the stand.

 The present invention will be described below based on an embodiment thereof.

In this embodiment, in the production of channel steel, a pair of flange portions are respectively inclined outward with respect to a perpendicular line in a hot rolling process, and a web portion has a convex shape, and its cross section has a W shape. Cold roll forming will be described in which an intermediate product having a web portion whose wall thickness is almost the same as the product dimension is formed and the convex web portion of the intermediate product is flattened.

Reference numeral 1 is a plurality of rollers for flattening a convex web portion 21 of the intermediate product 20 and cold-roll forming a channel steel having a parallel flange portion 22 and a flat web portion 21, and 2 is an upper roll. 3 is a lower roll, 4 is a pinch roller, and 5 is a roll shaft formed at both ends of the rollers 2 and 3.

Reference numeral 6 is a roll chock having a roller bearing therein for rotatably supporting the roll shaft 5, 7 is a screw reduction mechanism for applying a pressing force to the roll chock 6 for supporting the upper roll 2, and 8 is the upper and lower rolls. A hydraulically driven holding mechanism that does not include an electro-hydraulic servo for controlling the roll interval that applies a pressing force to the roll chock 6 that supports the two or three, and 10 forms a closed loop with the oil in the hydraulic cylinder 9 of the holding mechanism 8. However, the accumulator keeps the hydraulic pressure in the hydraulic cylinder 9 constant.

Then, in order to flatten the convex web portion 21 of the intermediate product 20 having a W-shaped cross section formed in the hot rolling, the roll gap is previously made the same as the product thickness of the channel steel, and the Roll chock 6 for supporting the cold forming roll shaft 5
On the other hand, the screw reduction mechanism 7 gives a resultant force of a reduction force for flattening the convex web portion 21 and a force for opposing the bending in the longitudinal direction generated when the web portion 21 is flattened. The intermediate product 20 having a W-shaped cross section is caught between the rolls 2 and 3. The gap between the rolls 2 and 3 is enlarged during biting, and an excessive load is momentarily applied to the roll chock 6. However, due to the oil that operates the hydraulic cylinder 9 of the reduction mechanism 8 and the accumulator 10 that forms a closed loop,
The excessive load applied to the roll chock 6 by adjusting the increase in the hydraulic pressure in the hydraulic cylinder 9 is absorbed by the accumulator 10.

When forming a channel steel having a wall portion 21 having a wall thickness of about 0.3 mm, the gap between the rolls 2 and 3 is expanded and an excessive load is applied to the roll chock 6 as described above, but the hydraulic pressure for pressing the roll chock 6 is increased. The increase in hydraulic pressure in the cylinder 9 is absorbed by the excessive load applied to the roll chock 6 by the accumulator 10, and the roll chock 6 and the stand (not shown) are formed even in the cold roll forming of channel steel having a large web portion 21. ) It should not be damaged.

As described above, according to the present invention, even if the intermediate product obtained by hot-rolling shaped steel or the like has a large variation in thickness, when the intermediate product is cold roll-formed, an excessive load is applied to the roll chock or the stand. It will not be damaged by being added. In addition, since it does not require an expensive hydraulic drive control device including an electro-hydraulic servo for controlling a roll interval used in a conventional rolling mill, it has extremely high practicality.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing rolls and pinch rollers used for cold roll processing, and FIG. 2 is a schematic view showing a cold roll forming apparatus provided with an overload prevention device of the present invention. is there. FIG. 3 is a side view of the intermediate product. 2: Upper roll, 3: Lower roll, 5: Roll axis, 6: Roll chock, 8: Hydraulic drive holding mechanism, 9: Hydraulic cylinder, 10: Acculator

Claims (1)

[Claims] 1. A cold forming roll comprising upper and lower rolls, which are arranged parallel to each other and at least one of which is rotationally driven, a roll shaft formed at both ends of the cold forming roll, and the roll shaft. A roll chock having a roller bearing inside for rotatably supporting, and a screw reduction mechanism for positioning a roll interval by applying a pressing force to the roll chock supporting the upper roll of the cold forming rolls, and the upper roll or the lower roll. In a plurality of sets of roll forming apparatus consisting of a hydraulically driven holding mechanism that does not include a roll gap control electric machine that applies a pressing force to at least one of the rolls-a hydraulic servo, a closed loop is formed together with a hydraulic cylinder of the holding mechanism. Once formed, the hydraulic pressure in the hydraulic circuit is always kept constant during normal operation to apply a predetermined pressing force to the work material and An overload prevention device in cold roll forming, which has an accumulator that absorbs a change in hydraulic pressure above a predetermined value so as to keep the hydraulic pressure constant when the work material is thicker than a predetermined thickness and is likely to be overloaded during forming. .