The present invention relates to a bending machine with a controlled-return bending die.
Bending machines have a bending device comprising a bending die or matrix and a bend arm, both rotating about an axis and being provided with co-operating counteracting members. These counteracting members clamp a section of a workpiece immediately after the section to be bent, according to a feeding direction of the workpiece in the bending machine. The workpiece is bent by causing both the matrix and the bend arm to move around the axis from an initial position to an end position. When a bending operation ends, the matrix is caused to return to its initial position.
Conventionally, a mechanism that is built-in or connected to a stationary part of the bending machine causes the matrix to return to its initial position. This implies some drawbacks, which are joined to the fact that said mechanism outside the bend arm might interfere with the bending operation.
In order to solve this problem, a matrix returning means has been provided being housed in the bend arm in the form of a spring element. However, this solution, according to which the matrix is automatically returned, has been abandoned because its operation is dangerous. Among other things, an automatic return of the matrix by means of a spring element is not always assured owing to the friction, the weight of the matrix and other causes, also in consideration that the spring member cannot be calibrated.
An object of the present invention is to allow a bending machine matrix to return to its start or initial position of bending operation safely and reliably by a control, whether the control is operated by a worker or whether the control is part of an automatic cycle.
Another object of the invention is to provide a mechanism for returning the matrix to its initial position that does not hinder the bending operation.
Therefore, the invention provides a bending machine with a controlled-return bending die, including a bending die or matrix mounted around a spindle having an axis y, a bend arm able to turn around on the same axis y, and co-operating counteracting means for clamping a section of workpiece to be bent in a start position of the matrix and the bend arm, a workpiece bending operation being performed for a workpiece section corresponding to an angle of rotation of the bend arm and the matrix around the axis y by driving means, the bend arm carrying on itself a controlled return means able to return the matrix to its start position at the end of workpiece bending operation.
The present invention will be described referring to a preferred embodiment thereof in connection with the enclosed drawings, in which:
With reference to the drawings, in
After a set angle rotation of the bend arm 4 and the matrix 2, connected thereto, by driving means (not shown), a pipe bending operation on the matrix is performed for a pipe section corresponding to set angle.
Hoses feeding a pressured fluid and electric wires are shown in
According to the invention, the matrix 2 is returned to the start position by return means acting on the matrix when the pipe bending operation is finished, after the bent pipe is removed from the bending machine. The return means is operated by a worker at the bending machine or by a control system.
This return means is housed in a compartment 7, as shown in
In particular, according to an embodiment thereof, the controlled return means comprises a single-acting cylinder 10, a section of flexible transmission 11 and an elastic stretching member 12. Such an embodiment is depicted in particular in
The single-acting cylinder 10 is fixed inside the compartment 7 in the bend arm 4. A free end 13 of the piston rod of the single-acting cylinder 10 is connected to an end 14 of the section of flexible transmission 11. The flexible transmission 11 is preferably a chain running on the ring gear 9, whose teeth mesh with chain links. The flexible transmission 11, beyond the ring gear 9, is attached with the other end 15 thereof to an end 16 of the elastic stretching member 12. The other end 17 of the elastic stretching member 12 is fixed by a pin 19 to a portion 18 being in any way rigidly connected to a fixed portion of the bend arm 4 inside the compartment 7, e.g. the portion 18 being integral with the same single-acting cylinder 10. Finally, the elastic stretching member 12 counteracts the piston rod of the single-acting cylinder.
The ring gear 9 is the power transmission element that is keyed to the spindle 3 and co-operates with the section of flexible transmission 11. The ring gear 9 is able to transform a traction applied to the flexible transmission 11 by the single-acting cylinder 10 into a rotation of the matrix 2 in a direction opposite the rotation caused by driving means of the bend arm 4, in order to return the matrix to the start position of bending operation. This can be performed only after a bent workpiece has been removed from the bending machine.
The single-acting cylinder 10 has its axis substantially perpendicular to the axis y of the spindle 3 and the free end 13 of the its piston rod is directed toward the spindle 3.
The elastic stretching member 12 is e.g. a traction resistant helical spring.
In the operation for bending a section of workpiece (not shown), the bend arm 4 is rotated by driving means of the bending machine, such as an electric or hydraulic motor, which are not described in detail, neither depicted in figures. When the bend arm 4 rotates around the axis y, the piston rod of the single-acting cylinder is pulled out by means of the section of flexible transmission 11 with a consequent shortening of the elastic stretching member 12. When the worker wants the matrix 2 to return to the start position of bending operation, the single-acting cylinder is fed with fluid which displaces the piston rod inside. The displacement of the piston rod transmits the traction to the section of flexible transmission 11 that being engaged with the ring gear 9 causes the matrix 2 to be rotated in the direction of the arrow F (see
The invention has been described by way of example, and variations and changes can be made without departing from the scope of the enclosed claims.
Number | Date | Country | Kind |
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RM2005A0049 | Feb 2005 | IT | national |
Number | Name | Date | Kind |
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2312122 | Parker et al. | Feb 1943 | A |
2667202 | Froedge | Jan 1954 | A |
2871909 | Bower | Feb 1959 | A |
3016943 | Kilham | Jan 1962 | A |
3205690 | Roessler, Jr. | Sep 1965 | A |
4063441 | Eaton et al. | Dec 1977 | A |
4552006 | Yogo | Nov 1985 | A |
Number | Date | Country |
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11 78 678 | Sep 1964 | DE |
Number | Date | Country | |
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20060174672 A1 | Aug 2006 | US |