GB2168278A - Double-roll sheet-metal bending machine - Google Patents

Abstract

A first roll 4 with a relatively rigid periphery and second roll 5, having a periphery of an elastic material 29 and provided with a mechanism for its rotation, are mounted in posts on a bed 1. The rolls 4, 5 are radially traversable with respect to each other. The roll 5 has a cylindrical portion 30 carrying an elastic ring 31 whose diameter exceeds the diameter of the roll 5 and whose thickness is equal to the thickness of the elastic periphery 29 of roll 5. The diameter of the rigid-periphery cylindrical portion 30 is substantially equal to the diameter of the rigid surface of the roll 5. A gap 38 between the inner surface of the elastic ring 31 and the outer surface of the rigid- periphery cylindrical portion 30 of the roll 5 accommodates a support 39 connected to the bed 1, the support 39 being in contact with the rigid- periphery cylindrical portion of the roll 5. <IMAGE>

Description

SPECIFICATION Double-roll sheet-metal bending machine This invention relates to double-roll sheet-metal bending machine. The invention can find most utility when applied for bending sheet metal into shells. In addition, the invention is also applicable for the manufacture of tubular items, segments, aeroplane skins, etc.

Constructions of modern machinery make extensive use of thin-walled structures and components fabricated by bending sheet materials.

At present the leading trend in mechanical engineering and machine building resides in increasing the so-called single-unit power or capacity or machines, which leads to their larger size. The size of machine components increase, too, including those bent from sheet metal on roll-type sheet bending machines. Thus, one of the problems to be solved with reference to sheet-bending machines is a larger effective length of rolls.

One of the most promising types of sheet-bending machines are at the present time double-roll sheetmetal bending machines featuring an elastic covering of either of the rolls. It would be desirable to extend the processing capabilities of such a machine and, more specifically, to provide a possibility of manufacturing long-sized thin-walled products in the machine by imparting higher rigidity to the elastic-periphery roll. It would also be desirable to save expensive material of the roll elastic coating, e.g. polyurethane, due to a reduced diameter of the roll, its rigidity remaining unaffected.

The present invention provides a double-roll sheet-metal bending machine, wherein a first roll having a relatively rigid periphery is rotatably mounted in posts which are connected to a bed, while a second roll having a periphery made of an elastic material is provided with a mechanism imparting rotation thereto and is mounted in said posts; said rolls are radiallytraversablewith respect to each other; the second roll has a rigid-periphery cylindrical portion having a diameter substantially equal to the diameter of the rigid peripheral surface of the second roll and provided with an elastic ring whose diameter exceeds that of the second roll and whose thickness is equal to that of the elastic periphery, while a gap established between the inner surface of the elastic ring and the outer surface of the rigid-periphery cylindrical portion of the second roll accommodates a support which is connected to the bed and is in contact with the rigidperiphery cylindrical portion of the second roll.

Such a constructional arrangement of the doubleroll sheet-metal bending machine enables itto manufacture long-sized thin-walled products owing to a higher rigidity of the elastic-periphery roll. Since the outer surface of the second roll with a periphery of an elastic material has cylindrical portions which rest on the posts connected to the bed, the second roll can be represented as a multisupport beam with a uniformly distributed load which under the same load experiences a lower bending moment, i.e. is subjected to a lower deflection.

Such a constructional arrangement of the second roll enables it to be of a smaller diameter, thus saving expensive material of the elastic coating.

Provision of an elastic ring at the or each rigidperiphery portion of the elastic-periphery second roll renders the elastic coating of the second roll efficient throughout its entire generatrix. Such a construction of the second roll makes it possible to increase its length to such an extent that is dependent on a minimum roll rigidity, limitation being also placed on the roll length by minimum roll torsional strength.

For instance, the now existing double-roll bending machines feature a limitation on the roll effective length equal to 2000 mm. With such a length of the elastic-periphery roll its maximum diameter is 400 mm. A two-fold increase in the roll effective length will result, with the now existing construction of the roll, in a four-fold increase in the bending moment applied, while the roll diameter will be increased 1.58 times, which involves a proportional change in the diameter of the elastic-periphery roll.

A double-roll sheet-metal bending machine made according to the invention enables the roll effective length to be extended to 4000 mm with the same diameter of the elastic-periphery roll equal to 400 mm.

In a preferred embodiment of the double-roll sheet-metal bending machine of the invention the support comprises two antifriction bearing mounted on a bracket which is affixed to the bed and has an opening for the elastic ring to pass, the sectional dimensions of the said opening in a plane passing through the longitudinal axes of the rolls exceeding the sectional dimensions of the elastic ring in the same plane.

Provision of the support as two antifriction bearings reduces the force of friction effective between the surface of the rigid-periphery cylindrical portion of the second roll and the surface of the support, which makes it possible to diminish the magnitude of the required torque on the elasticcoating roll. This in turn leads to reduced power consumption and overall dimensions of the second roll rotary-motion mechanism and hence to energy saving.

Higher rigidity of the elastic-periphery second roll is provided due to a positive connection of the bracket, carrying antifriction bearings, to the bed.

Provision of an opening in the bracket carrying antifriction bearings makes it possible to locate the elastic ring on the rigid-periphery cylindrical portion of the second roll and to impart rotation thereto concurrently with the roll, which in turn enables the roll elastic coating to be kept operable along the entire roll generatrix.

The double-roll sheet-metal bending machine provided according to the invention, is successfully applicable for the manufacture of tubular components of an aeroplane's anti-icing and lifesupport systems from high-strength aluminium and titanium alloys. When bending long thin-walled items up to 1.5 mm thick from titanium alloys and up to 3.0 mm thick from aluminium alloys, the load on the elastic-periphery second roll amounts to 200 kN/m. Under such a load the elastic-periphery roll has a diameter of 400 mm and a length of 4000 mm.

The elastic-periphery second roll having the aforespecified diameter provides for dimensional compactness of the double-roll sheet-metal bending machine, saving of the material, e.g. polyurethane, from which the elastic periphery is made, and saving of electric power for the rotary-motion drive of the second roll.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a general diagrammatic view of a doubleroll sheet-metal bending machine, without a blank, showing the supports of the first and second rolls partly in section; Figure 2 is an enlarged section on line Il-Il in Figure 1; and Figure 3 is a section on line Ill-Ill in Figure 2.

The double-roll sheet-metal bending machine, e.g. for bending shells, has a bed 1 with posts 2 and 3 and two rolls, viz a first roll 4 having a relatively rigid periphery, and a second roll 5 having a periphery made of an elastic material and provided with a mechanism 6 for rotating it about its longitudinal axis. The longitudinal axes of the first roll 4 and second roll 5 are parallel to each other.

The first roll 4 is rotatably mounted in the posts 2 and 3. With this purpose in view one end of the roll 4 rests with its journal 7 on a roller bearing 8, while a journal 9 on the other end of this roll is supported on two roller bearings 10. Half the periphery of the bearing 8 is encompassed by a cylindrical surface provided in a support 11, which is vertically transversable along guideways 12 (Figure 2) provided in the post 2. The support 11 has an opening 13 for convenient installation of the support 11 on a rod 15 of a hydraulic cylinder 16 with the aid of a nut 14, the hydraulic cylinder being adapted to actuate vertical traverse of the support 11 and being fixed stationary to the post 2. A slot 17 is provided in the post 2 to accommodate the hydraulic cylinder 16 and an opening 18 allows a finished shell 19 to be removed.

The bearings 10 (Figure 1) are pressed into a support 20 which is vertically traversable along guideways 21 provided in the post 3. The support 20 has an opening 22 for convenient installation of the support 20 on a rod 24 of a hydraulic cylinder 25, using a nut 23, the hydraulic cylinder being adapted to actuate vertical traverse of the support 20 and being fixed stationary to the post 3. The roll 4 is thus radially traversable towards the second roll 5.

The second roll 5 comprises a core 26 (Figure 2) carrying sleeves 27 (Figure 3), each of which is joined to the core 26 by a key 28 and has a periphery made of an elastic material 29. The second roll 5 has, e.g., three cylindrical portions having a rigid periphery, each of these portions being constituted by a sleeve 30 with flanges between which an elastic ring 31 is interposed, made of, e.g., polyurethane.

The diameter of the ring 31 exceeds that of the second roll 5, while its thickness is equal to that of the elastic periphery of the roll 5. Provision of the elastic ring 31 on each rigid-periphery cylindrical portion of the roll 5 renders the elastic coating of the second roll 5 efficient throughout the entire generatrix thereof. The diameter of the rigidperiphery cylindrical portion of the roll 5 is substantially equal to the diameter of the roll's rigid surface, that is, the outside diameter of the sleeve 30 (ignoring its flanges) is equal to the outside diameter of the sleeve 27. To ensure against axial displacement of the sleeves 27 and 30, washers 32 and nuts 33 are provided at the ends of the core 26.

A journal 34 (Figure 1) at one end of the core 26 rests on a roller bearing 35 forced into the post 2, while a journal 36 at the other end of the core 26 rests on a roller bearing 37 pressed into the post 3.

The journal 36 is associated, through a coupling (not shown), with the shaft (ndt shown) of the mechanism 6 for rotary motion of the roll 5, which is a hydraulic motor in this embodiment.

A gap 38 (Figure 8) defined by the inner surface of the elastic ring 31 and the outer rigid surface of the second roll, namely, the outer surface of the sleeve 30, accommodates a support 39 which is in contact with the rigid surface of the second roll, namely, the surface of the sleeve 30. The support 39 is made up of two antifriction bearings 40, each of which is mounted on a bracket 42 by a stud 41 (Figure 3), while the bracket 42 is affixed to the bed 1. The bracket 42 has an opening 43 (for passing the elastic ring 31) whose sectional dimensions in a plane containing the longitudinal axes of the rolls 4 and 5 exceed the sectional dimensions of the elastic ring 31 in the same plane.

The double-roll sheet-metal bending machine described above operates as follows.

Pressure is admitted to one of the chambers of the hydraulic cylinder 25 (Figure 1), to cause the rod 24 causes the support 20 to travel vertically along the guideways 21 together with the roll 4, and pressure is admitted to one of the chambers of the hydraulic cylinder 16, the rod 15 causes the support 11 to travel vertically, until its cylindrical surface contacts the surface of the bearing 8. Further on the hydraulic cylinders 16 and 25 actuate the radial traverse of the roll 4 towards the roll 5, whereby the roll 4 having a relatively rigid periphery forces for a preset depth into the second roll 5, having a periphery of elastic material. Deformation of the elastic coating sets up a return (reaction) pressure which is relayed to the bearing 35, the three supports 39, and the bearing 37. Thus, the second roll 5 can be represented as a multisupport beam with a uniformly distributed load which is subjected to the effect of a lower bending moment, i.e. experiences a lower deflection.

Rotation from the shaft of the hydraulic motor 6 is transmitted to the second roll 5 having an elastic coating. With the roll 5 rotating, the elastic rings 31 (Figure 2) and the roll 4 rotate, too, by virtue of the forces of friction. Then a sheet blank is fed in between the rotating rolls 4 and 5 to be formed into the shell 19. Next the blank is bent around the roll 4 until the blank comes out of the zone of contact of the rolls 4 and 5. Thereupon the hydraulic motor 6 is stopped, whereby the roll 5 and hence the roll 4 cease running. Then the hydraulic cylinder 16 causes the support 11 to move upwards to expose the opening 18 (Figure 2), while the hydraulic cylinder 25 actuates the support 20 to move upwards together with roll 4 until it comes out of contact with the elastic periphery of the roll 5.

Finally the finished shell 19 is withdrawn through the opening 18.

The double-roll sheet-metal bending machine described above features such a construction of the second roll having an elastic periphery that makes it possible to extend the roll length with a relatively small diameter, proceeding from the required rigidity limitations, restriction to the roll length being also placed by roll torsional strength. A reduced diameter of the second roll enables one to save expensive material of the elastic coating.

Claims (3)

1. double-roll sheet-metal bending machine, in which a first roll having a relatively rigid periphery is rotatably mounted in posts connected to a bed, and a second roll having a periphery of an elastic material on a rigid surface is provided with a mechanism for its rotation and is mounted in the said posts; the said rolls are radially traversable with respect to each other; the second roll has at least one rigid-periphery cylindrical portion with a diameter substantially equal to the diameter of the second roll rigid surface, the said cylindrical portion being provided with an elastic ring whose diameter exceeds the diameter of the second roll and whose thickness is equal to the thickness of the elastic periphery; and a gap defined between the inner surface of the elastic ring and the outer surface of the rigid-periphery cylindrical portion of the second roll accommodates a bed-connected support with which the rigid-periphery cylindrical portion of the second roll is in contact.

2. A machine as claimed in claim 1, in which the support comprises two antifriction bearings mounted on a bracket which is affixed to the bed and which has an opening for the elastic ring to pass, the sectional dimensions of the said opening in a plane containing the longitudinal axes of the rolls exceeding the sectional dimensions of the elastic ring in the same plane.

3. A double-roll sheet-metal bending machine substantially as described with reference to, and as shown in, the accompanying drawings.