GB2072552A - Clamping and rotating units for elongate workpieces in bending machines - Google Patents

Abstract

A clamping and rotating unit for elongate workpieces, such as metal wire lengths, comprises a member P for clamping and rotation of the workpiece about its longitudinal axis. The member is subjected to the action of an assembly for clamping the workpiece in the member, a part for the rotation of the workpiece clamped in the member, and a part for the ejection of the workpiece from the member after bending. The member and parts operate in synchronism with one another and with bending elements K1-K6 to enable wire articles to be provided with tridimensional bends. <IMAGE>

Description

SPECIFICATION Improvements in or relating to clamping and rotating units for elongate workpieces, such as wires, tubes and bars, for use in bending machines 'The present invention relates to clamping and rotating units for elongate workpieces, such as wires, tubes and bars supplied in the form of ltectilinear lengths. The invention also relates to bending machines including such units.

At present, in order to provide manufactured articles, particularly wire manufactured articles, the starting materials are lengths, that is rectilinear rods or pieces previously cut to measure, particularly iron wire, having a circular, square, polygonal or other cross-section, which on special machines are individually bent in a single plane by means of mechanical, hydraulic or pneumatic bending elements for possible later interassembling.

Working by means of wire bending is being increasingly developed in the industrial field, particularly for providing wire manufactured articles having tridimensional bendings to be used, for example, in the realization of seats, springs hooks, electrical appliance supports, electric immersion heaters and the like.

Hitherto, such bending was performed by previously manually rotating the length between one bending and another, or in different stages, resulting in considerable cost of the product.

According to the invention, there is provided a clamping and rotating unit for elongate workpieces to be bent, comprising a member for the clamping and rotation of the workpiece about its longitudinal axis, the member including means for clamping the workpiece in the member, means for the rotation of the clamped workpiece, means for ejecting the workpiece from the member upon completion of bending, and means for synchronising operation of the said means and one or more bending elements for bending the workpiece.

It is thus possible to provide machinery enabling bending, simultaneous clamping and rotation between one bending and another of 'a workpiece. Such a clamping and rotation unit may be provided for workpieces, particularly wire, tube or bar, allowing easy and ready operations with workpieces having different sections.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic front elevation view of an iron wire bending machine using a unit constituting a preferred embodiment of the invention, as preset between seven bending heads heads or elements; Figure 2 is a side view of Fig. 1; Figure 3 is a schematic side view showing a clamping and rotation unit; Figure 4 is an axial sectional view showing a portion supplying pressure fluid for clamping wire to be rotated; Figure 5 is a fragmentary vertical section showing parts for carrying out wire rotation and ejection; Figure 6 is a horizontal sectional view taken along a plane through N-N of Fig. 3; Figure 7 is an enlarged side view showing the clamping and rotation unit;; Figure 8 is an enlarged horizontal sectional view taken through a plane through N 1 -N 1 of Fig. 5; Figure 9 schematically shows the pressure fluid supply to the body or unit of Fig. 8; Figure 10 is an enlarged fragmentary vertical sectional view taken along the plane P1-P1 of Fig. 6; Figure 11 is a variant to Fig. 5 of wire rotation and ejection; Figure 12 is a sectional view taken along a plane through N2-N2 of Fig. 11; Figure 13 is a schematic fragmentary front elevational view showing a clamping and rotation unit as slidably mounted in a bending machine provided with three bending elements; Figures 14a- 14e are views showing the positions of a wire at different bending phases; Figure 15 schematically shows a variant to Fig. 13, with displacement of the clamping and rotation unit and with a two-stage cylinder;; Figure 16 is a view showing a variant of the operating cylinders, as in Figs. 13 and 15, applied to the bending elements; Figure 1 7 is a view showing a variant to Figs. 13 and 15 with electronic displacement of the clamping and rotation unit; and Figure 18 is a view showing a variant to Fig. 11 of the mechanical boundary for the angular displacement of the clamping body.

A clamping and rotation unit, which hereinafter will be simply referred to as the "unit", comprises a structure 1 of relatively small width with two sides 2 and 3 and a head 4 (Fig. 6). The unit further comprises a member A (Fig. 3) for receiving, clamping ad rotating an elongate workpiece, a part B for supplying a pressure fluid to the member A, a part C for imparting an angular rotation to the workpiece, and a part D for ejecting the workpiece on completion of bending.

The member A (Figs. 3 and 8) comprises a substantially cylindrical body 5, provided at its sides with two coaxial pins 6 and 7 rotable in respective supports or bearings 8 and 9, which, by means of screws 10, are mounted on the head 4 of the unit.

At its front, the body 5 (Fig. 7) has a radial notch 11 extending throughout the axial length of the body. Along the diameter and perpendicularly to the median plane of the notch 11, a cylindrical bore or hole is formed for receiving, in its portion 12 above the median plane of the notch (or vice versa), a piston or movable jaw 13 for clamping a workpiece S and, in its lower portion (or vice versa), a readily interchangeable fixed jaw or bearing 14. The piston 13, which may be a single- or double-acting piston, is movable by means of pressure oil and is subjected to a return bias away from the jaw 14 by means of a helical spring 15, which is housed within suitable cavities 15' and 15" in the piston 13 and the jaw 14. The jaw is secured in the body by means of cylindrical pins 16, laterally passing through the jaw.

At the median plane of the notch 11 and at the rear of the body 5, a cylindrical through hole 18 (Fig. 8) is provided with its axis at right angles to the axis of the body 5, for the passage therein of a pusher, to be further described hereinafter, for ejection of the workpiece upon completion of bending thereof.

The side pin 7 of the body 5 is provided with a chain wheel 19 (Figs. 5, 6 and 8) for imparting, together with members to be further described hereinafter, an angular rotation a of adjustable amplitude in the range of 0 to about 95'.

The operation of the piston 13 in the body 5 is by means of a fluid, such as oil, supplied thereto from the part B (Figs. 3 and 4) under pressure, via a flexible tube or hose 13' and an articulated element 20 (Figs. 8 and 9).

The element 20 comprises a small bar provided with a connection 21 to the flexible tube or hose 13', and a cylindrical projection 22 at right angles to the small bar, provided with a sealing ring 23, which is rotably housed within a respective cylindrical hole 5' at one side of the body 5. A hole 24 for the passage of fluid passes through the element 20. During the angular rotation of the body 5 (Fig. 9), the element 20 is constantly held at a substantially horizontal position due to the provision of an inclined plane 20', against which the end of the element provided with the connection 21 presses.

The above mentioned part B (Figs. 3 and 4), for supplying the pressure fluid required for control of the piston 13, comprises a cylinder assembly 25, pneumatically operated via a connection 26. A piston 27 is subjected to the action of a return spring 28. The end 29 of a piston rod, opposite the connection 26 is in turn effective as a piston for compressing oil in a cavity 30 of a cylinder 31, integral and coaxial with the cylinder 25, the oil being supplied viaa connection 31', the hose or flexible tube 13' and the articulated element 20, to the piston 13.

The selection of a pneumo-hydraulic pressure multiplier, as described, ensures good operation of the unit as a result of the constant pressure exerted on the piston 13. In order to compensate for unavoidable small oil leakages in the cylinder 31 and in the bore 12 past the piston 13. an accumulator 32 is placed above the cylinder assembly 25 and communicates with the cavity 30 via a hole 33, an annular groove 34 in the cylinder head 35, and axial grooves 36 in the end 29.

The pneumo-hydraulic multiplier, as above described, may be replaced by a conventional type of hydraulic circuit such as a motor pump with directional valve, an electro-hydraulic cylinder, a mechanical assembly, or a composite mechanical-hydraulic or mechanical-pneumatic system.

The assembly comprising the parts A and B for control of the clamping piston 13 may be formed as above described, or may be incorporated in the body 5.

The parts C and D comprise a set of cylinders, preferably of double-acting and pneumatic control type. The cylinders are mounted in superimposition and are disposed parallel to one another and in a common vertical plane.

The part D including an upper cylinder 40 (Fig. 5) performs the function of imparting a linear displacement to a pusher 42 for the ejection of the workpiece. Cylinder ends 43 and 44 (Figs. 5 and 10) have formed therein bores through which pass portions 45 and 45' of the piston rod of a piston 46, a stop 47 being mounted by screw threading and axially adjustably on the portion 45' which at the end of a forward stroke strikes a machine stopping switch 48, the machine comprising a plurality of bending elements and the clamping and rotation unit, and for inverting the fluid supply for return of the pusher 42. The end of the stem 45 of the cylinder 40 is provided with an arm 49 supporting the pusher.

The cylinder 41 (Fig. 5), performing the function of imparting a preset angular rotation to the body 5, has two ends 50 and 50' through which pass portions 51 and 51' of the piston rod of a piston 51". The end of the portion 51 is provided with an arm 52 for the operation of a closed link chain 53, fitted with a tensioning assembly 54, and running around two gear wheels 19 and 55. A third idle gear wheel 56 is arranged adjacent the operating chain wheel 19. The gear wheels and the chain are mounted in a plane P-P,- (Fig. 6) which is parallel to the plane P1-P1 containing the longitudinal axes of the cylinders 40 and 41.

The clamping of a workpiece S and the amplitude of angular rotation a of the body 5 are obtained as follows.

A cylindrical hole 60 (Fig. 10) in the portion 51', which hole is closed by a plug 61, receives the extreme portion of a stem 62 having an enlargement 63, which with the inner plug bottom 64 determines the adjustable forward stroke of the piston 51". The stem 62 also has a portion 65 with a screw thread, ending with a knob 66, which is provided with circumferential notches (not shown) for indexing thereof. The threaded portion 65 is also provided with a lock nut 66' for abutting against a bush or sleeve 67, which is axially displaceable by an amount L' relative to a structure 68 against a previously tensioned spring 69. The bush or sleeve 67 also comprises a pin 70 provided with a lock nut 70', the pin being partially threaded and freely slidable in the structure 68 for pressing at the end of the bush stroke a micro-switch 71 for triggering bending operations.After turning the knob 66, the portion 51' (Fig. 10) is longitudinally displaced until the respective shoulder thereof presses against the bottom 64 of the plug 61, imparting a short displacement L' to the stem 62 and accordingly to the bush 67 to control, as a result of the abuttment of the pin 70 against the switch 71, an electric circuit for controlling subsequent bending operations.

When one or more programmed bending elements K, K1, K2 . . (Fig. 1) have completed the working cycle thereof by forming one or more bendings in the same plane, an electrovalve (not shown) controlling the part C shifts the control flow (Fig. 5) from the portion 51' to the portion 51 for imparting a return stroke to the piston 51" to the initial position, and accordingly the return rotation of the body 5 to the initial position, which will be referred to as the 0 position. Because of being fixed to the body 5 by means of the clamping members 13 and 1 4 (Fig. 7), the workpiece S also rotates to the 0 position.

On returning to the initial position, the portion 51 along with the plug 61 actuates a switch 72 for controlling bending operations in a different plane.

During the same wire bending cycle, the body 5 can rotate again by an angle a, to remain at this new position until the required bending operations have been carried out.

Then, the body 5 can return to the 0 position, and then rotate again through a, and so on for an indefinite number of times, until all of the bending elements used in the programmed cycle have carried out the respective bending in the desired plane.

Upon completion of bending, the piston 27 of the pneumo-hydraulic multiplier B, and therewith the piston 13 of the body 5 (Figs. 4 and 7), move back to their respective starting positions. If not already at the 0 position, the body 5 returns thereto, after which the bent work-piece is ejected by means of the pusher 42. The above mentioned parts C and D can be replaced by hydraulic or oleopneumatic cylinders, hydraulic motors, electric motors, mechanical or electromechanical systems or the like. In turn, the above described switches can be replaced by mechanical stops (not shown in the drawings), electronic systems, or by pneumatic logic.Finally, the place of rotational drive of the body 5 through wheels and a chain, such a drive may be provided by using cables of metal or artificial material, smooth or toothed belts, tie rods, linkages, rotary cylinders, couplings of spur gears, wheel and pinion type of bevel gears or the like, or by rack, helical gear and worm screw assembly, or by mixed spur gear couplings and chain.

Thus, instead of the angular rotation of the body 5 being limited to about 95 , the rotation of the wire about its longitudinal axis could be as much as 190 , that is + 95 in one direction and - 95" in the other direction (Fig. 11), or even 360 , while being at the same time adjustable at any required intermediate position.By way of example, in the same bending cycle the length can be given a rotation of + 20 for a first bending operation, a rotation of - 30" for a second bending operation, a rotation of + 90 for a third bending operation, a rotation of + 10 for a fourth bending operation, a rotation of + 70 for a fifth bending operation, a rotation of - 90" for a sixth bending operation, and so on.

Figs. 11 and 12 show an alternative arrangement for rotating the body 5 for example by up to 1 90' or even up to 360 , including an electric motor 73, a position transducer 74, a position sensor 75 and an electronic computer 76 for data setting and processing as required for bending and rotation of the workpiece.

Control may be provided by using a circular transducer, not shown, arranged on the axis of the body 5 or on the axis of a gear wheel 55. The electric motor could also be replaced by hydraulic motor means, hydraulic or pneumatic cylinders or hydropneumatic cylinders, rotary cylinders and the like. A pneumatic brake (not shown) on the body 5 ensures the stability of the various positions during the bending operations. In this latter case, the members or parts B and D may still be used in various possible embodiments.

Instead of linkages for positioning of the body 5, there may be provided manually adjustable mechanical members 77 and 78 (Fig. 18). These members, of similar or identical construction, are arranged in opposite and coaxial relationship with respect to an axis 79.

Each member comprises at least one disc 80 rotatable relative to the axis 79, the discs being provided on the periphery with threaded stems 81, 81', 81" and so on, which are adjustable relative to the disc and arranged in alignment with the corresponding stems of the opposite disc. The discs 80 are replaceable, so that a particular set of discs may be provided for each bending sequence without having to adjust the stem whenever the bending operation is changed. The opposite ends thereof strike against a stop 82 which would be arranged on the stem 65. Moreover, as shown in Fig. 18, the spring denoted at 69 in Fig. 10, is now arranged at the mechanical member 78. Thus, an adjustable mechanical limit is provided for the stroke of the piston 51" for a precalculated rotation of the body 5.

It frequently occurs that the minimum spacing Q (Fig. 13) between the individual bending elements K, K1, K2 etc. is not sufficient for allowing bending of the work-piece when the required distance or spacing between the individual bends is very small. This problem can be solved by making the clamping and rotation unit longitudinally displaceable with respect to the bending machine. Modified assemblies for providing such displacement are shown in Figs. 13, 15 and 17.

The assembly of Fig. 13 is such as to allow a single displacement L2, adjustable by means of threaded stems 84 and nuts 85.

The assembly comprises two carriages 86 and 87 slidable on lower and upper frame guides 88 and 89, respectively, the carriages being interconnected by a support 90 integral with the rotation unit P. The stems 84 are integral with the support 90, but freely pass through a crosspiece 91, which is clamped to the guides. An hydraulic or pneumatic cylinder 92 is integral with the crosspiece 91.

An example will now be given of bending operations carried out by the assembly 83 having three bending elements K, K1 and K2, in accordance with the following sequence of operations: (a) The bending element K effects a first curvature or bending of work-piece S (a1 = 90 ), whereupon the bending head of the element K returns to enable the workpiece S to move freely parallel to the guides 88 and 89.

(b) The work-piece S is turned upwards of 90 by means of the rotation unit P.

(c) Rightward displacement of the unit P and the work-piece S previously subjected to the first bending (a1 = 90 ). Thereby, the minimum distance or spacing between the two elements K and K1 is Q2 (Fig. 14) (d) The element K1 then effects a second curvature or bending after which its bending head returns as described at (a).

(e) By means of the unit P, the work-piece is rotated to the starting 0 position, and then subjected to a last curvature or bending by means of the bending element K2, whereupon the work-piece can be ejected.

By the displacement assembly 93 shown in Fig. 15 and enabling two different displacements, the distance or spacing Q3 can be further reduced, as shown at (d) (Fig. 14) by using a two stage cylinder-piston having two different diameters. In the first cylinder, a piston 94 of smaller diameter is connected to the unit P through a rod 95, whereas a second piston 96, which is slidable within a cylinder of larger diameter, is traversed by an adjustable threaded stem 97. The piston 94 travels through the stroke L3 until it strikes the stem 97, thereby providing a first reduction in spacing (For example Q2 at c of Fig.

14). Upon completion of bending at this position, a further reduction in spacing between this bending and the next can be provided, by releasing the pressure at the rear of the piston 96, with resulting displacement of pistons 94 96 through a stroke L4.

The displacement unit shown in Fig. 17 can provide an indefinite number of positions owing to an electric motor 98 with a reduction gear 99, a pinion 99' and rack 99", a position transducer 100. a position sensor 101 and a computer (not shown). This embodiment could also be used with other components previously described.

The above described assemblies for longitudinal displacement can be also used for the bending elements where such assemblies cannot be used for the rotation unit due to overall space or symmetrical bendings, thickness or the like, for example when desiring to impart a different displacement to the elements K, K1, etc. (Fig. 16).

In particular cases, the displacement assembly could also be simultaneously used both for the bending elements and for the rotation unit.

Fig. 16 shows a unit P between two bending units (KS, K3, K1) and (K, K2, K4) operated by cylinder-piston assemblies (92 and 93) as described above (Figs.13 and 15).

Claims (17)

1. A clamping and rotating unit for elongate workpieces to be bent, comprising a member for the clamping and rotation of the workpiece about its longitudinal axis, the member including means for clamping the workpiece in the member, means for the rotation of the clamped workpiece, means for ejecting the workpiece from the member upon completion of bending, and means for synchronising operation of the said means and one or more bending elements for bending the workpiece.

2. A unit as claimed in claim 1, in which the member is arranged to effect angular rotation of the workpiece by an adjustable amount in the range of OG to at least 95 .

3. A unit as claimed in claim 1 or 2, in which the rotation means comprises a body laterally provided with pivot pins coaxial with an axis of the body, the body being mounted by means of lateral bearings to a head of the unit.

4. A unit as claimed in claim 3, in which the body has a radial notch extending throughout its length, a cylindrical hole extending perpendicularly to the median plane of the notch and diametrically of the body, the hole receiving on one side of the median plane a fluid-actuable piston and on the other side of the median plane a removable jaw for clamping the workpiece between the piston and the jaw.

5. A unit as claimed in claim 4, including means for supplying pressure fluid to the piston in the body including a flexible tube or hose connected to one end of a rigid elongate element provided at its other end with a cylindrical extension which enters the body, the rigid element being arranged to remain substantially horizontal during rotation of the 'body by having its first end pressed against an inclined plane.

6. A unit as claimed in claim 5, in which the means for supplying pressure fluid to the piston further includes a pneumohydraulic multiplier including a pneumatic cylinder and piston assembly, the piston having a piston rod arranged to act as a piston within an oilfilled cylinder disposed adjacent the cylinder and piston assembly.

7. A unit as claimed in any of the preceding claims, in which the means for ejecting a workpiece comprises a cylinder and piston assembly, the piston having a first rod portion on one side of the piston for ejecting the workpiece and a second rod portion on the other side of the piston provided with a stop for stopping a bending machine and for controlling the fluid flow to return the piston after ejection of a workpiece.

8. A unit as claimed in claim 7, when dependent on claim 3, in which the rotation means further comprises a further cylinder and piston assembly disposed below and in a common vertical plane with the cylinder and piston assembly of the ejecting means, the further piston having a rod portion connected to a chain which passes around gear wheels, one of which is mounted on the body.

9. A unit as claimed in claim 8, in which the chain and the gear wheels are disposed in a plane parallel to the plane containing the axes of the and the further cylinder and piston assemblies.

10. A unit as claimed in any one of claims 1 to 7, in which the rotation means is arranged to rotate the workpiece by an angle of up to a maximum of 360 and comprises a D.C. motor, a position transducer, a position sensor and an electronic computer.

11. A unit as claimed in any one of claims 1 to 9, in which the rotation means includes manually adjustable means for limiting rota .tion of the workpiece.

12. A unit as claimed in claim 11, in which the limiting means comprise a pair of replaceable rotable and mutually coaxial discs peripherally provided with axially adjustable stems arranged in axially aligned pairs, the discs being rotatable so as to position selectably the aligned pairs of stems in the path of a stop disposed on a reciprocable member for controlling rotation of the workpiece.

13. A clamping and rotating unit substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

14. A bending machine including at least one bending element and a clamping and rotating unit as claimed in any one of the preceding claims.

15. A machine as claimed in claim 14, in which the unit is displaceable on carriages by means of a cylinder and piston arrangement.

16. A machine as claimed in claim 15, in which the cylinder and piston arrangement allows selection of two different displacements and comprises a two-stage cylinder with different diameters, a first piston connected to the unit and a second piston connected to an adjustable rod constituting a movable stop for the first piston.

17. A machine as claimed in claim 14, in which the unit is displaceable by means of an electric motor, a reduction gear, a pinion and a rack, a position transducer, a position sensor and a computer.