MAZZOCCHI, Domenico (Via Grondana 7, Piacenza, I-29122, IT)
| Claims 1. A device for locking tools on press brakes, comprising: a tool holder (2) which can be or is securely engaged with an upper beam (3) of a press brake and comprising a first clamping surface (7); a clamping bracket (10) connected to the tool holder (2) and comprising a second clamping surface (14) facing the first clamping surface (7), in such a way as to delimit a housing for the shank (15) of a tool (16) to be locked in place; the clamping bracket (10) comprising, at its lower end, a tooth (20) which can engage in a cavity (19) made in the tool (16) to be locked in place; a wedge (22) interposed between the bracket (10) and the tool holder (2) at an upper end of the bracket (10) opposite to the tooth (20); characterised in that the wedge (22) can move relative to the bracket (10) and is slidably connected to the tool holder (2) in a plane (P) which is sloping relative to a direction of movement (X) of the upper beam (3); and also being characterised in that it comprises means (24) for pushing the wedge (22) away from the bracket (10) and against the tool holder (2), causing the bracket (10) to perform a roto- translating movement in such a way as to lift the tool (16), bring it into contact with the tool holder (2) and clamp it between the first and the second clamping surfaces (7, 14). 2. The device according to claim 1, wherein the wedge (22) is slidably housed in a cavity (21) made in the bracket (10). 3. The device according to claim 1 or 2, wherein the wedge (22) is engaged in a cavity (23) made in the tool holder (2). 4. The device according to claim 1, 2 or 3, wherein the wedge (22) comprises a sloping surface (22e) in contact with the tool holder (2) in the sloping plane (P). 5. The device according to claim 3, wherein the cavity (23) in the tool holder (2) comprises a sloping surface (23 c) in contact with the wedge (22) in the sloping plane (P). 6. The device according to claim 3, wherein the wedge (22) comprises a sloping surface (22e) in contact with a sloping surface (23c) made in the cavity (23) in the tool holder (2); the sloping surfaces (22e, 23c) making contact with each other in the sloping plane (P). 7. The device according to claim 3, wherein the means (24) for pushing the wedge (22) comprise at least one grub screw inserted in the bracket (10) and comprising one end (24a) acting on the wedge (22). 8. The device according to any of the foregoing claims, wherein the sloping plane (P) slopes down towards the bracket (10). 9. The device according to any of the foregoing claims, comprising at least one pin (11) fixed to the tool holder (2) and extending in a direction substantially transversal to the longitudinal extension of the upper beam (3); said at least one pin (11) being inserted, with predetermined play, in a respective hole (12) made in the clamping bracket (10), for allowing the bracket (10) roto-translating movement. 10. The device according to any of the forgoing claims, wherein the tooth (20) of the bracket (10) comprises a plastic or rubber cover (20a) which can engage against the tool (16). 11. The device according to any of the foregoing claims, also comprising elastic means (26) interposed between the bracket (10) and the tool holder (2) and acting vertically on the bracket (10) to push it downwards. |
Device for locking tools on press brakes
Technical Field
This invention relates to device for locking tools on press brakes. Background Art
As is known, press brakes comprise an upper beam, to which a tool or punch with a lower operating end is connected, and a fixed lower beam, on which at least one die having a cavity normally formed by a "V"-shaped profile is connected. The upper beam can move vertically, controlled by suitable hydraulic actuators, between a home position and an operating position. In the home position the upper beam holds the tool at a distance from the die, allowing the insertion between the tool and the die of a sheet of metal to be pressed. In the operating position, the upper beam brings the lower end of the tool partly into the cavity of the die, in such a way as to bend the sheet positioned between the two elements. Depending on the thickness of the sheet to be bent, the bending angle and the material of which the sheet is made, different tools and dies are mounted on the press brake. The tools are held and locked on the upper beam by means of suitable locking mechanisms which comprise a tool holder integral with the upper beam and a clamp able to move between an open position, necessary for fitting or removing the tools, and a closed position, in which the tools are rigidly connected to the tool holder, allowing pressing. As is known, the locking devices are also usually equipped with a safety device to prevent the tools fitted on the upper beam from falling every time the devices are put in the open position.
Prior art locking devices are mechanically complex, since they must serve three functions simultaneously:
- closing and clamping the tool shank between the clamp and the tool holder;
- bringing into contact in a vertical direction the tool shank against a contact surface of the tool holder during clamping;
- preventing the tools fitted on the upper beam from falling every time the tool clamps are put in the open position.
Document WO2004052570 illustrates, for example, a locking device for press brake tools comprising a tool holder rigidly mounted on the upper beam, a clamp connected to the tool holder and comprising a supporting surface for the tool, formed by a lower hook, and a clamping surface set up to close on and lock the tool shank between the clamping surface itself and the tool holder. The lower hook can engage in a groove made in the tool. The clamp also comprises, on the side opposite to the hook, a sloping surface in contact with a sloping surface made on the tool holder. When the clamp closes on the tool, the clamp moves upwards in a diagonal direction relative to the tool holder, thus locking the tool on the press brake and in a vertical direction bringing the tool into contact against the tool holder.
Disclosure of the Invention
With regard to this, the Applicant felt the need to study and propose a device for locking tools on press brakes which is able to provide at least one of the following advantages:
- having a simple, economical structure, thus limiting production and maintenance costs;
- having simple and safe operation;
- allowing its installation and correct operation even on existing press brakes, requiring only small modifications on said press brakes.
The above-mentioned aims are achieved by providing a clamp or bracket designed to clamp the tool, which incorporates a wedge which is mobile and can engage in a suitable groove made in the tool holder integral with the upper beam.
More specifically, this invention relates to a device for locking tools on press brakes comprising:
- a tool holder which can be or is securely engaged with an upper beam of a press brake and comprising a first clamping surface;
- a clamping bracket connected to the tool holder and comprising a second clamping surface facing the first clamping surface, in such a way as to delimit a housing for the shank of a tool to be locked in place; the clamping bracket comprising, at its lower end, a tooth which can engage in a cavity made in the tool to be locked in place;
- a wedge interposed between the bracket and the tool holder at an upper end of the bracket which is opposite to the end with the tooth;
- characterised in that the wedge can move relative to the bracket and is slidably connected to the tool holder in a plane which is sloping relative to a direction of movement of the upper beam; and in that it comprises means for pushing the wedge away from the bracket and against the tool holder, causing the bracket to perform a roto-translating movement in such a way as to lift the tool, bring it into contact with the tool holder and clamp it between the first and the second clamping surfaces.
That structure, in which the wedge can move relative to the bracket, allows the bracket to rotate and rise (pulling the tool with it) unhindered, guaranteeing correct connection of the various elements (bracket, tool holder and tool) for closing and secure locking. In particular, the tool is moved upwards until it makes contact with a lower contact surface of the tool holder. Said surface is subjected to the entire pressure during pressing.
This invention may also comprise one or more of the preferred features described below.
The wedge is preferably slidably housed in a cavity made in the bracket. The wedge preferably engages in a cavity made in the tool holder.
In more detail, the wedge comprises a first portion housed in the bracket and a second portion which comes out of the bracket and is inserted in the tool holder.
As a result, the overall structure is compact.
The wedge preferably comprises a sloping surface in contact with the tool holder in said sloping plane.
The cavity in the tool holder preferably comprises a sloping surface in contact with the wedge in said sloping plane.
In a preferred embodiment, the wedge comprises a sloping surface in contact with a sloping surface made in the tool holder cavity. The sloping surfaces make contact with each other in the sloping plane.
The sloping plane preferably slopes down towards the bracket.
In more detail, the second portion of the wedge, which comes out of the bracket, has a sloping surface which is in contact with and slides on a sloping surface delimiting the tool holder cavity.
That construction solution is simple and inexpensive to produce.
According to one embodiment, the means for pushing the wedge comprise at least one grub screw inserted in the bracket and comprising an end which acts on the wedge. The grub screw allows precise adjustment of the roto-translating movement by the bracket and tool clamping.
According to one embodiment, the device comprises at least one pin fixed to the tool holder and extending in a direction substantially transversal to the longitudinal extension of the upper beam. Said at least one pin is inserted, with predetermined play, in a respective hole made in the clamping bracket, for allowing the roto-translating movement of the bracket. The pin supports the bracket when it is not closed on the tool and allows the bracket to rotate and translate to correctly lock the tool in place.
The bracket tooth preferably comprises a plastic or rubber cover which can engage against the tool.
The cover, preferably made of PTFE, deforms slightly during tool 16 clamping and compensates for any play between the tools 16 fitted side by side on a single bracket 10 (segmented tools), allowing the tools to make contact correctly.
The cover also allows the tools to be easily made to slide along the upper beam so that they can be positioned at the desired point and if necessary substituted once they are worn.
The device also preferably comprises elastic means interposed between the bracket and the tool holder and acting vertically on the bracket to push it downwards.
The elastic means assist bracket opening, achieved by unscrewing the grub screw, making the bracket movement smoother.
Brief Description of the Drawings
Other features and advantages will become more apparent from the detailed description below of a preferred non-limiting embodiment of a device for locking tools on press brakes according to this invention.
The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without restricting the scope of the invention and in which:
- Figure 1 is a side view, partly in cross-section, of a device according to this invention connected to a tool and in a first operating configuration;
- Figure la is an enlarged view of a portion of Figure 1 ;
- Figure 2 shows the device of Figure 1 in a second operating configuration;
- Figure 3 is a front view of the device according to the arrow "A" of Figure 1, without the tool.
Detailed Description of the Preferred Embodiments of the Invention
With reference to the accompanying drawings, the numeral 1 denotes in its entirety a device for locking tools on press brakes.
The device 1 comprises a tool holder 2 which in the preferred embodiment illustrated is an element, called an "intermediate part" in the specific technical sector, which is or can be rigidly connected, in a known way not described or illustrated, to an upper beam 3 of a press brake. In other embodiments, not illustrated, the tool holder 2 may be the upper beam 3 itself.
The tool holder 2 comprises a main body 4 connected to the upper beam 3 and a projection 5 extending below the main body 4 (when the intermediate part is mounted on the press brake) and forming a step with it. In more detail, the main body 4 has a surface 6 which, when the intermediate part is mounted on the press brake, remains facing towards the operator and is substantially vertical. The surface 6 extends parallel with the longitudinal extension of the upper beam 3. The projection 5 comprises a first clamping surface 7 which, when the intermediate part is mounted on the press brake, remains facing towards the operator and is substantially vertical. The first clamping surface 7 extends parallel with the longitudinal extension of the upper beam 3. The surface 6 of the main body and the first clamping surface 7 are connected by a horizontal surface 8. At its free lower end the projection 5 also comprises a contact surface 9, preferably horizontal (that is to say, perpendicular to a direction of movement "X" of the upper beam 3).
The device 1 also comprises a clamping bracket 10 having a plate-shaped outline, which is connected to the tool holder 2 by pins 11 formed by flange screws. The pins 11 (of which there are two in the non-limiting embodiment illustrated) pass through the through holes 12 or slots made in the clamping bracket 10, are screwed into and locked in the tool holder 2 and extend at a right angle from the first clamping surface 7. Each of the pins 11 comprises a head 13 which prevents the pin 11 from slipping out of the clamping bracket 10. The through holes 12 are elongate in a vertical direction and the housings for the heads 13 are sized in such a way as to allow some play for the clamping bracket 10.
The clamping bracket 10 has a second clamping surface 14 which, when the bracket 10 is fitted on the tool holder 2, faces the first clamping surface 7 and is spaced from it, thus delimiting a housing for the shank 15 of a tool or a punch 16 to be locked in place.
The tool 16, of the known type, comprises an operating portion 17, opposite to the shank 15, designed to engage with and deform the sheet to be bent, operating in conjunction with a die mounted on the lower beam (not illustrated). The tool 16 also comprises a contact surface 18 alongside the shank 15 and a cavity 19 (groove) made in a surface of the tool 16 located on the opposite side of the shank 15 to the contact surface 18. At its lower end adjacent to the second clamping surface 14, the clamping bracket 10 has a tooth 20 which can engage in the cavity 19 made in the tool 16. The tooth 20 extends along the entire longitudinal extension of the bracket 10 (parallel with the longitudinal extension of the upper beam 3). The tooth 20 comprises a plastic or rubber cover 20a, preferably made of polytetrafluoroethylene (PTFE), facing towards the projection 5 and upwards and designed to make contact with and to support the tool 16, as described in more detail below.
The bracket 10 also comprises, close to an upper end opposite to the tooth 20 relative to the through holes 12, a cavity 21 which is open towards the surface 6 of the tool holder 2. The cavity 21 extends along the entire longitudinal extension of the bracket 10 and is delimited (Figure la) by two parallel lateral surfaces, one upper 21a and one lower 21b and by a rear surface 21c.
The cavity 21 in the clamping bracket 10 partly houses a wedge 22 which can slide in the cavity 21. The wedge 22 is a bar extending along the entire length of the cavity 21. In a cross-section clearly visible in Figure la, the wedge 22 has an outline with an upper side 22a facing the upper lateral surface 21a of the cavity 21, a lower side 22b which is opposite to the upper side 22a and facing the lower lateral side 21b of the cavity 21, a rear side 22c facing the rear surface 21c of the cavity 21, a front side 22d which is parallel with the rear side 22c and an oblique side 22e connecting the front side 22d and the lower side 22b. The oblique side 22e corresponds with a sloping surface of the wedge 22 and forms a tapered portion of the wedge 22.
The tapered portion of the wedge 22 comes out of the cavity 21 and is housed in a cavity 23 (groove) made in the surface 6 of the main body 4 of the tool holder 2. The cavity 23 in the tool holder 2 is delimited, in cross-section (Figure la), by an upper surface 23a, a sloping surface 23c and a rear surface 23b connecting the upper surface 23a and the sloping surface 23c. The sloping surface 23c of the cavity 23 in the tool holder 2 is at least partly in contact with the sloping surface 22e of the wedge 22 in a sloping plane "P" which slopes down towards the bracket 10.
Also screwed into the clamping bracket 10 is a grub screw 24 which passes through the bracket 10 and has one end 24a inside the cavity 21 and in contact with the rear side 22c of the wedge 22. An opposite end 24b of the grub screw 24 emerges from the bracket 10 on the side opposite to the cavity 21. The grub screw 24 forms an element for pushing the wedge 22 away from the bracket 10.
A helical spring 25 is positioned around each pin 11 and acts against the tool holder 2 and against the bracket 10 in such a way as to push those two elements away from each other.
Moreover, there are preferably elastic means 26 acting in a vertical direction above the clamping bracket 10 in such a way as to push the bracket 10 downwards. In accordance with the embodiment illustrated in the accompanying drawings, the elastic means 26 comprise helical springs which are interposed between the bracket 10 and an element 27 which is securely fixed, for example using screws, to the surface 6 of the tool holder 2. In practice, before clamping, the bracket 10 and the wedge 22 are in the configuration shown in Figure 1. The grub screw 24 is in the back position and the end 24a inside the cavity 21 is in a position close to the rear surface 21c. Although being partly housed in the cavity 23 in the tool holder 2, the wedge 22 is slightly spaced from the rear surface 23b of that cavity 23 (Figures 1 and la). In this configuration, the shank 15 of the tool 16 is interposed between the first and second clamping surfaces 7 and 14 but is not compressed and locked between them. Moreover, the tool 16 contact surface 18 is slightly spaced from the projection 5 contact surface 9 (Figure 1). The tool 16 therefore remains hanging from the tooth 20 and can be made to slide on the tooth 20 and along the upper beam 3.
When the grub screw 24 is tightened, the wedge 22 translates in the cavity 21 in the bracket 10, is pushed into the cavity 23 in the tool holder 2 and slides on the sloping surface 23 c, moving slightly upwards and also pulling with it, in its vertical movement, the bracket 10 by means of the tooth 20. The bracket 10 lifts the tool 16, opposing the elastic means 26, bringing the contact surface 18 of the tool 16 into contact with the contact surface 9 of the projection 5. The deformability of the rubber or plastic cover 20a present on the tooth 20 allows even two or more tools 16 mounted on a single bracket 10 (segmented tools) to be brought into contact correctly. When the wedge 22 completes its stroke (making contact with the rear surface 23b of the cavity 23 in the tool holder 2, further tightening of the grub screw 24 causes the upper portion of the bracket 10 to move away from the tool holder 2 and the lower portion of the bracket 10 to move towards the tool holder 2. The bracket 10 rotates about a centre of rotation substantially located at the pins 11 and clamps the shank 15 of the tool 16 between the first and second clamping surfaces 7 and 14 (Figure 2).
To release the tool 16, the grub screw 24 is simply unscrewed. The bracket 10 downward movement is caused not just by gravity, but also by the elastic means 26.