DE29510041U1 - Device for forming thin flat workpieces - Google Patents

Description

Device for forming thin flat workpieces

The invention relates to a device for forming

flat workpieces with a stamping tool and

a die tool with complementary shape surfaces.

Such devices are known as bending devices for use in intermittent bending processes, in which a workpiece to be formed is arranged between a punch tool and a die tool with mutually complementary forming surfaces and is deformed when the punch tool and die tool are joined together with force.

These devices are usually used in mass production in large, automatic machines that process the workpieces supplied in the same way. Manual processing of a workpiece to adapt it to geometries that were unknown when the tools were created is not provided for.

The invention is based on the object of creating a device of the type mentioned at the beginning, which allows workpieces to be shaped to adapt to very different geometries, in particular under time pressure such as during surgical interventions in bone surgery.

This object is achieved according to the invention in that the punch tool and the die tool can be removably inserted into holders attached to the arms of a pair of pliers, whereby in the open position of the pliers the tool

piece can be inserted between the die tool and the punch tool and, when the pliers are in the closed position, the forming surfaces are joined together to form the workpiece.
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Because the punch tool and the die tool are removably attached to the pliers, it is possible to manually machine the workpiece and also to quickly change the tools.

In particular, the forces exerted can be easily dosed so that, for example, with an open tool during so-called free bending, the workpiece can be easily adapted to different geometries. Closed tools are conveniently provided with identification numbers that allow quick access to the tools required to form special geometries.

The holders and the inserted workpieces are expediently designed in such a way that either the punch tool or the die tool can be inserted into a holder. This avoids confusion with asymmetrically designed pliers.

In a further practical embodiment, a die tool and a stamp tool are attached to a holder on two sides, with the arms of the pliers being connected to one another via two swivel joints and a connecting piece. In this embodiment, tool sets with two differently designed mold surfaces are available by simply folding the arms over.

The stamping tools and matrix tools are advantageously made of biologically compatible materials such as titanium, titanium alloys, ceramics or surgical stainless steel. In special designs, the molding surfaces of stamping tools and matrix tools have fine contours. For example, the fine contours are designed in such a way that a contour can be impressed into the workpiece, which leads to a reduced contact surface on a bone or to improved growth of bone tissue. In other designs, the fine contour can be used to introduce a slot geometry into a workpiece made of a biologically compatible, resorbable plastic, so that its surface is enlarged.

The workpiece to be formed is made of a biocompatible material such as titanium, titanium alloys, implant steels or biocompatible, resorbable plastics.

Further expedient embodiments and advantages of the invention are the subject of the subclaims and the following description of embodiments with reference to the figures of the drawing. They show:

Fig. 1 a forming pliers as a device for forming flat workpieces in the open position with a workpiece arranged between a punch tool and a die tool in side view,

Fig. 2 the forming pliers according to Fig. 1 in closed position,

Fig. 3 the forming pliers according to Fig. 1 and Fig. 2 in the open position with a workpiece deformed in sections according to the forming surfaces of the punch tool and the die tool,

Fig. 4 the forming pliers according to Fig. 3 with a workpiece deformed in a further section,

Fig. 5 the area of a forming pliers according to Fig. 1 to Fig. 4 in the area of the holder in the open position with another double-formed workpiece,

Fig. 6 a forming pliers with holders into which a punch tool and a die tool can be inserted in side view,

Fig. 7 a forming pliers in side view with a stamp tool and a die tool, each of which is wrapped with an electrically heatable resistance wire,

Fig. 8 a stamping tool with a retaining pin protruding over the mold surface and a die tool with a retaining recess for receiving the retaining pin in a partially sectioned side view,

Fig. 9 a stamping tool with a retractable holding pin and an associated die tool in a partially sectioned side view,

Fig. 10 a die holder in top view and a die tool that can be inserted into the die holder in side view,

Fig. 11 a stamp holder in top view and a stamp tool that can be inserted into the stamp holder in side view and

Fig. 12 a punch tool and a die tool with associated holders and securing means to prevent accidental slipping out in a partially sectioned side view.

Fig. 1 shows a side view of a device designed as a forming tongs 1 for forming flat workpieces in the open position. The forming tongs have a punch arm 2 and a die arm 3, which are equipped with handles 4 at one end.

A stamp holder 5 is attached to the stamp arm 2, into which a stamp tool 6 is inserted. In the embodiment shown in Fig. 1, the stamp tool 6 has a stamp forming surface 7 that is convexly curved outwards. Furthermore, a stamp identification number 8 is inscribed on the side of the stamp tool 6, indicating, for example, the radius of the stamp forming surface 7.

A die holder 9 is attached to the die arm 3, into which a die tool 10 is inserted. The die tool 10 has a die forming surface 11, not visible in the illustration according to Fig. 1, which is concavely curved towards the inside and which corresponds to a recess in a side surface of the die tool 10.

embossed die number 12 is designed to be complementary to the stamping surface 7.

In the illustration according to Fig. 1, a mesh grid 13 is inserted between the punch tool 6 and the matrix tool 10 as the workpiece to be formed, as is used in bone surgery to fix fractures or to cover bone defects, for example in the skull and facial area.

The arms 2, 3 of the forming tongs 1 are connected to one another at their ends opposite the handles 4 by a swivel joint 14. The punch arm 2 has two articulated jaws 15, 16, in which jaw bores are made that run transversely to the longitudinal axis of the punch arm 2. Between the articulated jaws 15, 16, an articulated web 19 is inserted, which is attached to the die arm 3 via an angle section 17 and a right-angled connecting piece 18 and has a web bore that is aligned with the jaw bores made in the articulated jaws 15, 16. An articulated axis 20 is inserted into the jaw bores and the web bore.

In a modification, tools are provided for open bending, in which the die tool, for example, has a ring as a forming surface with an inner diameter that is complementary to the forming surface of the punch tool. By inserting the forming surface of the punch tool more or less deeply into the complementary ring of the die tool, differently designed forming areas can be introduced into the workpiece.

Fig. 2 shows the forming tongs 1 according to Fig. 1 in the closed position with the mesh grid in between 13. The length of the connecting piece 18 is so

arranged so that the stamping surface 7 in parallel alignment of the stamping arm 2 to the die arm 3 with deformation of the interposed mesh lattice 13 comes to lie precisely in relation to the complementary die forming surface 11.

Fig. 3 shows the forming tongs 1 according to Fig. 1 and Fig. 2 in the open position after forming the mesh grid 13 in a forming area 21. The radius of the curved forming area 21 corresponds to the radius of the forming surfaces 7, 11.

Fig. 4 shows the forming tongs 1 according to Fig. 1 to Fig. 3 in the open position with a mesh grid 13 turned over compared to the illustration according to Fig. 3 with a further forming area 22 which is curved in the opposite direction to the already introduced forming area 21.

Fig. 5 shows a side view of the forming tongs 1 according to Fig. 1 to Fig. 4 in the open position in the area of the holders 5, 9 with an interposed mesh grid 13, into which a curvature 24 has been embossed superimposed on a basic shape 23.

From Fig. 3, Fig. 4 and Fig. 5 it can be seen that the mesh grid 13 can be precisely shaped to different geometries in a simple manner using the stamp tool 6 and the die tool 10. By exchanging the stamp tool 6 and the die tool 10 for tools with different radii or differently designed mold surfaces, a precise, easy-to-implement adjustment can be made even to complicated spatial geometries.

Fig. 6 shows a side view of a double forming pliers 25 in the area around a first double holder 26 and a second double holder 27. A first die tool 28 with a cylindrically concavely curved first die forming surface 29 is inserted into the first double holder 26. A first stamp tool 30 with a first stamp forming surface 31 that is cylindrically convexly curved complementarily to the first die forming surface 29 is attached to the second double holder 27.

Furthermore, in the double forming pliers 25 shown in Fig. 6, a second stamping tool 32 with a cylindrically convexly curved second stamping surface 33 is interchangeably mounted in the first double holder 26. Accordingly, a second die tool 34 with a cylindrically concavely curved second die forming surface 35 complementary to the second stamping surface 33 of the second stamping tool 32 is provided on the second double holder 27. The stamping surfaces 31, 33 and the associated die forming surfaces 28, 35 each have different radii of curvature.

The double holders 26, 27 are firmly attached to double arms 36, 37 of the double forming pliers 25. The double arms 36, 37 have joint jaws 38, 39, 40, 41 at their ends shown in Fig. 6 to swivel joints 42, 43, which have jaw holes made at right angles to the longitudinal axes of the double arms 36, 37. A connecting piece 44 is inserted between the joint jaws 38, 39, 40, 41, which has web holes aligned with the jaw holes of the joint jaws 38, 39, 40, 41. Joint axes 45, 46 are inserted through the holes of the joint jaws 38, 39, 40, 41 and the connecting piece 44.

In the arrangement of the double arms 36, 37 shown in Fig. 6, the first die tool 28 and the first punch tool 30 are aligned facing each other. When the double arms 36, 37 are folded over, the second punch tool 32 is opposite the second die tool 34. Due to the complementary design of the associated forming surfaces 29, 31; 33, 35 with different surface geometries, differently designed forming areas can be bent into a workpiece using the double forming pliers 25 without changing the tools 28, 30; 32, 34.

Fig. 7 shows, as an embodiment of a device for forming flat workpieces with heatable tools, a side view of a forming tong 1 according to Fig. 1 to Fig. 5, in which both the stamping tool 6 and the die tool 10 are surrounded by heating coils 47, 48. The heating coils 47, 48 are wound from electrically insulated resistance wires 49, 50. The resistance wires 49, 50 are connected to a power supply unit (not shown in Fig. 1) and heat up when electrical energy is applied. Depending on the power loss, both the stamping tool 6 and the die tool 10 heat up.

In the illustration according to Fig. 7, a thermoplastic plastic plate 51 with a high bending elasticity at room temperature is inserted between the stamping tool 6 and the die tool 10 as the workpiece to be formed. Due to the higher temperatures of the stamping tool 6 and the die tool 10 compared to the ambient temperature, the interposed area of the plastic plate 51 is plastically deformable and has a shape after cooling and removal from the molding tongs 1. Preferably, the

Plastic plate 51 is heated so that the high bending elasticity is also essentially retained in the molding area.

When manufacturing the workpiece from a metallic implant material, the risk of microcracks can be reduced by forming at an increased temperature.

In a modification of the embodiment shown in Fig. 7, only one heating coil is provided, which is placed either around the stamping tool 6 or the die tool 10. In a further modification, the heating coils 47, 48 emit different power losses. Due to the resulting temperature gradient between the stamping tool 6 and the die tool 10, different stress states can be impressed on the formed workpiece in the forming area compared to the original state, particularly in the case of a short forming process.

Fig. 8 shows a partially sectioned side view of a stamping tool 52 that can be inserted into the holders 5; 26, 27 of the pliers 1; 25 and has a centering pin 54 that protrudes over a stamping surface 53. A die tool 55 that is assigned to the stamping tool 52 and can be inserted into the holders 9; 26, 27 of the pliers 1; 25 and has a die surface 56 that is complementary to the stamping surface 53 has a centering recess 57 into which the centering pin 54 can be inserted when the stamping tool 52 and the die tool 55 are joined together.

A perforated plate 58 is provided as the workpiece to be formed with the punch tool 52 and the die tool 55, which has at least one centering hole 59 for

Insertion of the centering pin 54 so that a reproducible alignment of the perforated plate 58 is created.

Fig. 9 shows in a partially sectioned side view another embodiment of a stamping tool 60 that can be inserted into the holders 5; 26, 27 of the pliers 1; 25 with a centering pin 61 that can be moved against the spring force of a compression spring 62 in a centrally inserted pin recess 63 so far that the end of the centering pin 61 is flush with a stamping surface 64 of the stamping tool 60.

For example, the die tool 10 with a smooth, unperforated die forming surface 11 can be used as a counterpart to the stamping tool 60 shown in Fig. 9. When the stamping tool 60 and the die tool 10 are joined together, the centering pin 61, which passes through the centering hole 59 of the perforated plate 58, is countersunk in the pin recess 63.

Fig. 10 shows the die arm 3 of the molding pliers 1 according to Fig. 1 in the area of the die holder 9 in a top view. The die holder 9 has an annular cross-section and has a locking groove 65 that is open on the inside. The inner diameter of the die holder 9 is so large that insertion openings 67, 68 are formed between the inner wall 66 of the die holder 9 and the die arm 3. In the area of the insertion openings 67, 68, locking balls 69, 70 are provided on the die arm 3.

Furthermore, in Fig. 10 a die tool 71 is shown in side view, which has a nose-like

curved, non-rotationally symmetrical die forming surface 72. The die tool 71 has two protruding die insertion pins 73, 74, with a laterally protruding securing projection 75 being attached to the die insertion pin 73. Furthermore, the die insertion pins 73, 74 have securing holes 76, 77 on their opposite sides.

The distance and the thickness of the die insertion pins 73, 74 as well as the arrangement of the securing projection 75 are adapted to the size of the insertion openings 67, 68 as well as the arrangement of the securing groove 65, so that the die tool 71 can be inserted into the die holder 9 in a form-fitting manner and secured against twisting and unintentional slipping out.

Fig. 11 shows a top view corresponding to Fig. 10 of the stamp arm 2 of the forming tongs 1 according to Fig. 1 with the ring-shaped stamp holder 5. The wall thickness of the stamp holder 5 is reduced compared to that of the die holder 9, so that relatively large insertion openings 79, 80 are formed between the inner wall 78 of the stamp holder 5 and the stamp arm 2. The stamp holder 5 also has a locking groove 81 that opens towards the inner wall 78. The stamp arm 2 also has locking balls 82, 83 arranged in the area of the insertion openings 79, 80.

For positive engagement in the insertion openings 79, 80, a stamping tool 85 is provided, which is equipped with a nose-like, non-rotationally symmetrical stamping surface 84 complementary to the die forming surface 72 and has stamp insertion pins 86, 87 which are stronger than the die insertion pins 73, 74, whereby the stamp insertion

pins 86, 87 also have securing holes 88, 89. A securing projection 90 is attached to a punch insertion pin 87. When the punch tool 85 is inserted into the punch holder 5, the locking balls 82, 83 engage in the securing holes 88, 89 and the securing projection 90 engages in the securing groove 81.

By providing securing projections 75, 90 engaging in securing grooves 65, 81, it is ensured that the die tool 71 and the punch tool 85 are inserted in the same direction. Furthermore, the different thicknesses of the die insertion pins 74, 75 and the punch insertion pins 86, 87 ensure that they are clearly assigned to the punch holder 5 and the die holder 9, which prevents the tools 71, 85 from being accidentally confused.

Fig. 12 shows a partially sectioned side view of the die tool 71 and the die holder 9 according to Fig. 10 in the assembled state. The locking balls 69, 70 are inserted into a locking recess 91 that runs across the die arm 3 and are secured against slipping out by a diameter of the locking recess 91 that is narrowed in the end area. A locking spring 92 is provided between the locking balls 69, 70, which presses the locking ball 69, 70 outwards. The same applies when inserting the punch tool 85 into the punch holder 5.

In the arrangement of the die holder 9 and the die tool 71 shown in Fig. 12, the locking balls 69, 70 engage in the locking holes 76, 77 made in the die insertion pins 73, 74, so that the die tool 71 is prevented from accidentally slipping out of the die holder 9.

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Rather, when removing the die tool 71, a pressure force must be exerted on the ends of the die insertion pins 73, 74 that penetrate through the die holder 9, in order to move the locking balls 69, 70 into the locking recess 91 against the pressure force of the locking spring 92.

Claims (16)

PROTECTION CLAIMS 1. Device for forming flat workpieces (13, 51, 58) with a stamping tool and a die tool with mutually complementary forming surfaces, characterized in that the stamping tool (6, 30, 32, 52, 60, 85) and the die tool (10, 28, 34, 55, 71) can be removably inserted into holders (6, 9; 26, 27) attached to arms (2, 3; 36, 37) of a pair of pliers (1; 25), wherein in the open position of the pliers (1; 25) the workpiece (13, 51, 58) can be introduced between the die tool (10, 28, 34, 55, 71) and the stamping tool (6, 30, 32, 52, 60, 85) and in the closed position Position of the pliers (1; 25) the forming surfaces (7, 11, 29, 31, 33, 35, 53, 56, 64, 72, 84) are joined together to form the workpiece (13, 51, 58). 2. Device according to claim 1, characterized in that the holder (5, 26, 27) for the stamping tool (6, 30, 32, 52, 60, 85) and the holder (9, 26, 27) for the die tool (10, 28, 34, 55, 71) as well as sections (86, 87; 73, 74) of the stamping tool (6, 30, 32, 52, 60, 85) and the die tool (10, 28, 34, 55, 71) that can be inserted into the holder (5, 9, 26, 27) are designed differently, so that neither the stamping tool (6, 28, 30, 52, 60, 85) in the holder (9, 26, 27) for the die tool (10, 28, 34, 55, 71) nor the die tool (10, 28, 34, 55, 71) can be inserted into the holder (5, 26, 27) provided for the stamp tool (6, 30, 32, 52, 60, 85). 3. Device according to claim 1 or 2, characterized in that the holders (5, 9, 26, 27) are arranged between a joint (14, 42, 43) and handles (4) of the pliers (1, 25). 4. Device according to one of claims 1 to 3, characterized in that on each holder (25, 26) a die tool (28, 34) can be inserted on one side and a stamp tool (30, 32) on another side. 5. Device according to one of claims 1 to 4, characterized in that the arms (2, 3; 36, 37) are connected at their ends adjacent to the holders (5, 9; 26, 27) to a connecting piece (18, 44) via at least one swivel joint (14; 42, 43). 6. Device according to claim 5, characterized in that the connecting piece (18, 44) is dimensioned such that the arms (2, 3; 36, 37) are aligned parallel to one another in the closed position of the pliers (1; 25). 7. Device according to one of claims 1 to 6, characterized in that the stamping tool (6) and/or the die tool (10) are heatable. 8. Device according to claim 7, characterized in that the stamping tool (6) and the die tool (10) are wound with electrically heatable resistance wires (49, 50). 9. Device according to one of claims 1 to 8, characterized in that the stamping tool (52, 60) in the open position of the pliers (1, 25) via a pin (54, 61) protruding beyond the mold surface (53, 64). 10. Device according to claim 9, characterized in that the pin (61) can be displaced against the pressure of a compression spring (62) introduced into the stamping tool (60) until it is at least flush with the mold surface (64). 11. Device according to claim 9, characterized in that the pin (54) is fixed and that a die tool (55) complementary to the punch tool (52) has a recess (57) for receiving the pin (54) in the closed position of the pliers (1, 25). 12. Device according to one of claims 1 to 11, characterized in that the holders (5, 9, 26, 27) and the stamping tool (6, 30, 32, 52, 60, 85) and the die tool (10, 28, 34, 55, 71) have means (79, 86; 80, 87; 81, 90; 67, 73; 68, 74; 65, 75) for the rotationally fixed insertion of the punch tool (6, 30, 32, 52, 60, 85) and the die tool (10, 28, 34, 55, 71). 13. Device according to one of claims 1 to 12, characterized in that the holders (5, 9, 26, 27) as well as the stamping tool (6, 30, 32, 52, 60, 85) and the die tool (10, 28, 34, 55, 71) have locking means (69, 70, 76, 77; 82, 83, 88, 89) that can be brought into engagement with one another to prevent the stamping tool (6, 30, 32, 52, 60, 85) and the die tool (10, 28, 34, 55, 71) from accidentally slipping out of the holders (5, 9, 26, 27). •••Φ&Bgr;·· 14. Device according to one of claims 1 to 13, characterized in that the stamping tool (5, 30, 32, 52, 60, 85) and the matrix tool (10, 28, 34, 55, 71) are made of a biologically compatible material, in particular titanium, titanium alloys, ceramics or surgical stainless steel. 15. Device according to one of claims 1 to 14, characterized in that the forming surfaces of the stamp tool and/or the die tool have a fine contour with which a structure can be impressed into the workpiece. 16. Device according to one of claims 1 to 14, characterized in that the forming surfaces of the stamp tool and/or the die tool have a fine contour with which a slot geometry can be introduced into the workpiece. 39/18.05,95