CN211990303U - Equipment for forming workpieces by extrusion - Google Patents

Abstract

The utility model relates to a device for forming a workpiece by extrusion, which comprises a forming tool and a forming driving device with a control device. The control device for the forming drive has a force measuring device, a comparison unit and a control unit. By means of the force measuring device sensing the magnitude of the feed force, the forming tool and the workpiece are loaded with the feed force relative to each other by means of the forming drive while forming the workpiece. The magnitude of the feed force is compared with a defined limit value by means of a comparison unit. When the magnitude of the measured feed force reaches or exceeds a limit value, the control unit actuates the motor-driven forming drive, so that the forming drive causes the forming tool and the workpiece to be moved relative to each other after a partial forming stroke over a portion of the forming length. The return stroke moves over the return stroke length and after the return stroke over the other shaping-section length towards each other with another shaping-section stroke.

Description

Equipment for forming workpieces by extrusion

technical field

The utility model relates to a device for forming workpieces by extrusion, especially cold extrusion, the device has

forming tools, and

a motor-driven forming drive, controllable by a preferably digital control device, by means of which the forming tool and the workpiece to be formed can be moved over each other in forming strokes while the workpiece is being formed A forming length is moved over a return length away from each other with a return stroke, wherein the forming tool and the workpiece can be loaded with a feed force relative to each other by means of the forming drive while forming the workpiece.

Background technique

Such prior art is disclosed in DE19735486A1.

In the case of the prior art, the workpiece to be shaped and the shaping die mounted on the workpiece are moved towards each other along the feed axis. Due to the associated loading of the workpiece by the forming die, the material of the workpiece begins to flow and the workpiece is formed by the forming die during the relative movement of the forming die and the workpiece along the feed axis. The relative movement of the forming tool and the workpiece is implemented as a non-uniform movement. The frequency generating device causes the forming tool and the workpiece to be moved alternately towards and away from each other until the workpiece is formed over the forming length to be machined.

Utility model content

Optimization of the prior art is the task of the present invention.

According to the invention, this task is solved by a device for forming workpieces by extrusion, in particular cold extrusion, which device has

forming tools, and

a motor-driven forming drive, controllable by a preferably digital control device, by means of which the forming tool and the workpiece to be formed can be moved over a forming stroke towards each other while the workpiece is being formed The forming length is moved away from each other over a return length with a return stroke, wherein the forming tool and the workpiece can be loaded with a feed force relative to each other by means of the forming drive while the workpiece is being formed, wherein the forming drive is used for the forming drive The control device has:

a force measuring device, by means of which the magnitude of the feed force can be measured, the forming tool and the workpiece are loaded with the feed force relative to each other by means of the forming drive while forming the workpiece,

a comparison unit, by means of which it is possible to compare the magnitude of the feed force measured by the force-measuring device with a defined limit value for the magnitude of the feed force, the forming tool and the workpiece in the process of forming the workpiece by means of the forming drive cases are loaded with a feed force relative to each other, and

a control unit by means of which the motor-driven shaping drive can be actuated in this way when the measured magnitude of the feed force reaches or exceeds a defined limit value for the magnitude of the feed force , such that the forming drive moves the forming tool and the workpiece relative to each other in a return stroke over a return length after performing a partial forming stroke over a portion of the forming length and with another forming after the return stroke The partial strokes are moved towards each other over another forming-part length.

During extrusion, the forming tool exerts a pressure on the workpiece to be formed, which pressure is determined such that the flow limit of the workpiece material is exceeded. For this purpose, the forming tool and the workpiece to be formed are loaded with a feed force relative to each other. If the flow of workpiece material has already started, the forming tool and the workpiece are moved towards each other in a forming stroke during the forming of the workpiece by the forming tool. In this case, there is the possibility of moving only the forming tool relative to the workpiece to be formed or only the workpiece to be formed relative to the forming tool or even the forming tool during the forming stroke carried out under the action of the feed force. The workpiece to be formed moves. Once the material of the workpiece begins to flow, the magnitude of the pressure to be exerted on the workpiece by the forming tool and thus the feed force to be exerted decreases. However, in the further progress of the forming process, it is necessary to increase the magnitude of the feed force, on the basis of which the relative movement between the forming tool and the workpiece that is required to shape the workpiece occurs. Considerable reasons for the necessity of increasing the feed force during the relative movement of the forming tool and the workpiece are the gradual reduction of the lubricant film and/or the solidification of the material in flow, which during the forming A lubricant is added between the tool and the workpiece to be formed already at the beginning of the forming stroke. Correspondingly, an increase in the feed force applied to shape the workpiece indicates an increase in friction due to the relative movement of the forming tool and the workpiece. According to the invention, in particular workpieces made of metal, eg steel, are processed.

According to the invention, a limit value is defined for the magnitude of the feed force applied to the forming tool and/or the workpiece to be formed, thereby also indirectly limiting the range of friction between the forming tool and the workpiece. If the friction between the forming tool and the workpiece to be formed, which occurs due to the relative movement between the forming tool and the workpiece before the workpiece is machined over the entire forming length, reaches or exceeds a certain level during the forming stroke, then in order to The forming stroke occurs with which the feed force applied to the forming tool and/or the workpiece to be formed reaches or exceeds a defined limit value and the forming stroke is interrupted after the forming-partial stroke. The forming tool and the workpiece which has not yet been machined are then moved away from each other in a return stroke over a return stroke length. In the resulting gap between the forming tool and the workpiece, a lubricant can be added again, which causes a relatively small gap between the forming tool and the workpiece to be formed in the further forming partial stroke following the return stroke friction. In this way, if necessary, the processing takes so long until the workpiece has been machined over the entire forming length.

By limiting the friction that occurs between the forming tool and the workpiece to be formed during the course of the forming stroke, friction-related wear on the forming tool is minimized in the case of the invention and the consequences of forming the workpiece are avoided Friction-dependent damage to quality.

At the same time, it is ensured that the magnitude of the friction that occurs between the forming tool and the workpiece to be formed during the forming stroke develops in terms of magnitude and the associated amount of the feed force applied to the forming tool and/or the workpiece to be formed. The return stroke of the forming tool and/or the workpiece to be formed, which is triggered by reaching or exceeding a limit value for the magnitude of the feed force, is carried out only when required by the development in terms of value.

According to the invention, it is thus conceivable that the forming tool and the workpiece to be formed are moved towards each other without interruption over the entire forming length and thus the forming of the workpiece is carried out in one run. The return stroke is carried out only when it is actually required for the reasons described above.

Thus, according to the invention, a minimum wear of the forming tool and a maximum machining quality of the formed workpiece are achieved with a minimum overall length of the path on which the forming tool and the workpiece to be formed must face each other Movement until the end of the forming process. The minimization of the magnitude of the relative movement carried out by the forming tool and the workpiece to be formed until the end of the forming process in turn has the effect of reducing wear. Furthermore, the minimization according to the invention of the total length of the paths traveled by the forming tool and the workpiece relative to each other leads to an optimization in terms of time of the individual forming processes and therefore, if necessary, also to a minimization of the cycle time of the higher-level production process. change.

Preferred embodiments according to the present invention are described below.

In a preferred type of construction of the shaping device according to the invention, the control device for the shaping drive has an evaluation unit, which is connected to the force measuring device and by means of which the force measuring device can The measured magnitude of the feed force defines a limit value for the magnitude of the feed force with which the forming tool and the workpiece are loaded with respect to each other by means of the forming drive while forming the workpiece.

In a further advantageous configuration of the invention, the analytical processing unit of the control device is used to define the value of the feed force at which the workpiece material begins to flow under the action of the feed force applied to the forming tool and/or the workpiece. At the limit of the magnitude of the feed force, the forming tool and the workpiece are loaded with the feed force relative to each other while the workpiece is being formed. Here, according to the invention, in particular an evaluation unit is used which defines a limit value which is equal to or slightly smaller than the magnitude of the feed force at which the workpiece material begins to flow.

The magnitude of the feed force applied to the forming tool and/or the workpiece when the material of the workpiece to be machined begins to flow can be obtained computationally taking into account relevant parameters, in particular relevant material property values.

The design of the device according to the invention is characterized by an optimal adjustment to the specific machining situation in that the evaluation unit of the control device for the forming drive in the device is designed in such a way that, in order to limit the use in forming the workpiece, The limit value of the magnitude of the feed force applied to the forming tool and/or the workpiece in the case of taking into account the magnitude of the feed force, which has been measured before the workpiece material begins to flow. By measuring the magnitude of the feed force at which the workpiece material has actually started to flow in the particular machining situation, a representative basis for the particular machining situation is obtained in order to define limit values for the magnitude of the feed force. Additionally, machine-determined process discontinuities and dispersions are sensed and compensated for. Overall, the device according to the invention obtains a self-learning property. The magnitude of the feed force at which the material of the workpiece to be formed begins to flow in a specific machining situation is influenced, for example, by the wear state of the forming tool and/or the state of the tool and workpiece surfaces in contact with each other.

In a further preferred configuration of the device according to the invention, an evaluation unit for the control device of the shaping drive is provided, by means of which the shaping length can be variably defined for shaping the workpiece. The limit value of the magnitude of the feed force applied to the forming tool and/or the workpiece without This feature of the invention takes into account that the conditions during the forming of the workpiece over the forming length can vary, for example, depending on the tool, the workpiece and/or the material. The preferred possibility according to the invention for variably defining limit values for the magnitude of the feed force provides a self-learning device variant. In this case, individual limit values for the magnitude of the feed force can be defined for each forming partial stroke by an evaluation unit of the control device for the forming drive.

Description of drawings

The present invention is explained in detail below with reference to exemplary schematic diagrams. The attached figure shows:

Figure 1 Equipment for extruding workpieces, and

FIG. 2 shows a force-time diagram of a forming process carried out by means of the apparatus according to FIG. 1 .

Detailed ways

According to FIG. 1 , a device 1 for forming workpieces comprises a forming tool 2 as a forming tool, which can be moved by means of a forming drive 3 along a movement axis 4 and here relative to the workpiece to be formed. In the example shown, the workpiece is an axle blank 5 made of steel for a drive axle of a motor vehicle. The shaft blank 5 is clamped by means of the clamping unit 6 and thus does not change in position along the movement axis 4 .

The reduced diameter shaft end 7 of the shaft blank 5 is provided by cold extrusion with external teeth, the teeth of which extend along the shaft end 7 parallel to the movement axis 4 . For this purpose, the shaping tool 2 has corresponding shaping teeth 8 . The profile teeth 8 comprise teeth, not shown in detail, which run parallel to the movement axis 4 on the walls of the reduced-diameter hollow-cylindrical section 9 of the die opening 10 of the profile die 2 . Starting from the hollow-cylindrical section 9 of reduced diameter, the die opening 10 widens towards the shaft blank 5 as a conical inlet 11 of the forming die 2 .

In the present case, the shaping drive 3 of the device 1 is a hydraulic piston-cylinder drive with a stationary cylinder 12 and a piston 13 guided movably along the movement axis 4 in the interior of the cylinder 12 . Other types of drive designs are conceivable, such as servo cylinders.

A forming die 2 is mounted on the piston rod 14 of the piston 13 outside the cylinder 12 , wherein the connection between the piston rod 14 and the forming die 2 is established by a rigid coupling 15 .

In the region of the rigid coupling 15 there is a force measuring device 16 which, like the evaluation unit 17 , the comparison unit 18 and the control unit 19 , is part of the programmable digital control device 20 of the shaping drive 3 . The force measuring device 16 comprises a force sensor of the conventional construction type.

The lubricant supply 21 is drawn on the side of the forming die 2 remote from the rigid coupling 15 . The lubricant supply 21 is attached to the forming die 2 and is movable together with the forming die along the movement axis 4 .

In order to form the shaft blank 5 at the shaft end 7 , the forming drive 3 is actuated starting from the situation shown in FIG. 1 . Thus, the piston 13 of the forming drive 3 is moved to the right in the drawing in the feed direction (arrow 22 ) together with the piston rod 14 and the forming die 2 connected to this piston rod. Thereby, the shaft end 7 of the shaft blank 5 enters the die opening 10 of the forming die 2 along the movement axis 4 . The cross-section of the shaft end 7 has an interference with respect to the cross-section of the reduced diameter hollow cylindrical section 9 of the die opening 10 , measured via the tops of the teeth of the profile teeth 8 .

Thus, during the movement of the forming tool 2 relative to the shaft blank 5 in the feed direction 22 along the movement axis 4 , the profile teeth 8 of the profile die 2 pass through the teeth of the profile teeth in the feed direction 22 . The upper front end meets the end side of the shaft end 7 of the shaft blank 5 . Under the action of the axial feed force applied to the forming die 2 by the forming drive 3 in the feeding direction 22 , the shaft blank 5 is loaded with pressure in the feeding direction 22 by the forming die 2 . The magnitude of the feed force applied to the forming die 2 is measured by means of the force measuring device 16 of the digital control device 20 and supplied to the evaluation unit 17 of the digital control device 20 .

The magnitude of the feed force exerted by the forming drive 3 on the forming die 2 abutting against the end side of the shaft end 7 increases until the material of the shaft blank 5 is applied by the forming die 2 to the shaft end 7 . It starts to flow under the action of the pressure on it.

The onset of material flow is manifested by a sudden drop in the resistance with which the shaft blank 5 opposes the forming die 2 loaded with a force in the feed direction 22 , and thus also by a sudden drop in the feed force exerted on the forming die 2 . On the basis of the resulting force curve, the evaluation unit 17 identifies which of the magnitudes of the feed force measured by the force measuring device 16 is to be supplied further, which in the specific machining situation is applied by the forming drive 3 to the This magnitude of the feed force on the forming die 2 initiates the flow of material of the shaft blank 5 . Based on this magnitude of the feed force, the evaluation unit 17 defines a limit value for the magnitude of the feed force applied by the forming drive 3 to the forming die 2 during the forming of the shaft blank 5 , wherein in the present case The limit value is determined such that it is slightly lower than the magnitude of the feed force exerted by the forming drive 3 on the forming die 2 at the beginning of the material flow. Limit values defined by the evaluation unit 17 for the magnitude of the feed force applied by the forming drive 3 to the forming die 2 during forming of the shaft blank 5 are stored in the comparison unit 18 of the digital control device 20 .

After the material of the shaft blank 5 begins to flow, the forming die 2 is moved in the feed direction 22 along the shaft end 7 of the shaft blank 5 driven by the forming drive 3 during the forming of the shaft blank 5 .

Lubricant has been added to the shaft end 7 of the shaft blank 5 by means of the lubricant supply 21 before the movement carried out by the forming die 2 during the forming of the shaft blank 5 , which lubricant is applied to the forming teeth of the forming die 2 . A lubricating film is formed between the part 8 and the surface of the shaft end 7 of the shaft blank 5 . The lubricating film is responsible for reducing friction between the teeth of the profile teeth 8 of the shaping tool 2 on the one hand and the area of the shaft end 7 of the shaft blank 5 formed by the teeth of the profile teeth 8 on the other hand. As the forming die 2 moves forward, the lubricating film between the forming teeth 8 of the forming die 2 and the shaft end 7 of the shaft blank 5 is gradually reduced and the movement of the forming die 2 relative to the shaft blank 5 is determined by friction Resisted by increasing resistance to movement. In order to overcome the movement resistance, the forming drive 3 applies a feed force of increasing magnitude to the forming die 2 in the feed direction 22 .

During the axial movement of the shaping tool 2 relative to the shaft end 7 of the shaft blank 5 immediately after the start of the material flow, the force measurement device 16 also continuously measures the amount of the feed force applied to the shaping tool 2 . Instantaneous value. The obtained measured values are continuously compared with previously defined limit values for the magnitude of the feed force exerted on the forming die 2 in the comparison unit 18 . If the magnitude of the feed force measured during the forming stroke of the forming tool 2 reaches the limit value stored in the comparison unit 18 before the forming over the entire forming length is completed, the control unit 19 by means of the digital control device 20 will The forming drive 3 is actuated so that the movement of the forming tool 2 in the feed direction 22 is interrupted and the forming tool 2 is instead stored in the digital control device 20 in the retraction direction (arrow 23 ), which is opposite to the feed direction 22 . movement over the return length.

Due to the return stroke of the forming tool 2 carried out after the forming-partial stroke, the previously formed length section of the shaft end 7 of the shaft blank 5 is accessible for the addition of lubricant via the lubricant supply 21 . . After the lubricant has been applied to the shaft end 7 of the shaft blank 5 , the forming tool 2 is moved again in the feed direction 22 by means of the forming drive 3 from the retracted position, until the contact surface provided on the forming tool 2 is reached. The teeth of the profile toothing 8 , which are located at the front longitudinal ends in the feed direction 22 , strike the unmachined portion of the shaft end 7 of the shaft blank 5 . By increasing the feed force exerted by the forming drive 3 on the forming die 2, the material of the shaft blank 5 is reflowed.

The magnitude of the feed force applied to the forming die 2 when the material of the shaft blank 5 begins to flow again is measured by the force measuring device 16 and used as a basis in the analytical processing unit 17 of the digital control device 20 for redefining and subsequently stored in the Limit values in the comparison unit 18 for the magnitude of the feed force applied to the forming die 2 during the forming of the shaft blank 5 .

Immediately after the resumption of the material flow, a further forming-partial stroke of the forming tool 2 relative to the shaft blank 5 takes place. During this additional forming-partial stroke, the magnitude of the feed force exerted by the forming drive 3 on the forming die 2 is also acquired by the force measuring device 16 and is compared with the previously defined value in the comparison unit 18 . limit values for comparison. If the magnitude of the measured feed force reaches a previously defined limit value, the forming drive 3 is actuated again by the control unit 19 of the digital control device 20 for the return stroke of the forming tool 2 before the further forming partial stroke is carried out. This is done until the shaft end 7 of the shaft blank 5 has been machined over the entire forming length.

FIG. 2 shows by way of example the time course of the feed force exerted on the forming tool 2 by the forming drive 3 during a forming-part stroke of the forming process in which the forming tool 2 carries out a plurality of formings. Partial strokes and between forming-partial strokes, in each case a return stroke is carried out until the shaft end 7 of the relevant shaft blank 5 is provided with the desired external toothing over its entire length.

Immediately following the return stroke of the forming tool 2, at the end of which the forming tool 2 is retracted over the previously formed partial length relative to the remaining length of the shaft end 7 that has not yet been formed, the passage of the forming drive begins at point I. 3 Reloading of the forming die 2 with the applied feed force in the feed direction 22 . At point II, the forming tool 2 hits the unmachined part of the length of the shaft end 7 by means of the forming teeth 8 in the feed direction 22 . The axial feed force exerted by the forming drive 3 on the forming die 2 up to that time is required to move the forming die 2 over the machined part of the length of the shaft end 7 and to overcome the friction occurring here.

If the shaping tool 2 hits the still machined portion of the length of the shaft end 7 in the feed direction 22 via the shaping teeth 8 (point II), a relatively strongly increased feed force is applied to the shaping tool 2 . Axial pressure loading of the shaft end 7 through the forming die 2 is caused, so that the material of the shaft end 7 starts to flow (point III). Depending on the magnitude of the feed force exerted by the forming drive 3 on the forming die 2 in the feeding direction 22, measured by means of the force measuring device 16 at the beginning of the material flow, the numerical control device 20 defines in the above-mentioned manner Due to the limiting value of the magnitude of the feed force exerted by the forming drive 3 on the forming die 2 during the forming of the shaft blank 5, this limit value is somewhat smaller than the magnitude of the feed force at the start of the material flow in point III. The defined limit values for the magnitude of the feed force applied by the forming drive 3 to the forming tool 2 during forming of the shaft blank 5 are stored in the comparison unit 18 of the digital control device 20 .

After the material flow at the shaft end 7 begins, the feed force applied to the forming die 2 first decreases. The forming die 2 moves along the shaft end 7 during its forming. The lubricating film formed by the lubricant previously added to the shaft end 7, on the one hand, between the profile teeth 8 of the forming tool 2 moving in the feed direction 22 and the shaft end 7, on the other hand, forms as it forms. The die 2 is gradually reduced along the advancing movement of the shaft end 7 . An increase in the feed force exerted by the forming drive 3 on the forming die 2 occurs with the reduction of the lubricating film.

The magnitude of the feed force exerted by the forming drive 3 on the forming die 2 eventually reaches the limit value previously defined and stored in the comparison unit 18 of the digital control device 20 at point IV. The control unit 19 of the digital control device 20 therefore activates the forming drive 3 in such a way that the feed of the forming tool 2 is interrupted and the forming tool 2 is relative to the shaft end over the length of the return stroke before the introduction of a further forming partial stroke of the forming tool 2 . The unfinished portion of the portion 7 is retracted (point Ia).

Claims (4)

1. Apparatus for shaping a workpiece (5) by extrusion, the apparatus having:

a forming tool (2), and

a motor-driven forming drive (3) which can be controlled by a control device (20) and by means of which the forming tool (2) and the workpiece (5) to be formed can be moved over a forming length with a forming stroke towards one another and over a return length with a return stroke away from one another with the workpiece (5) being formed, wherein the forming tool (2) and the workpiece (5) can be loaded with a feed force relative to one another with the workpiece (5) being formed by means of the forming drive (3),

it is characterized in that the preparation method is characterized in that,

the control device (20) for the forming drive (3) has:

a force measuring device (16) by means of which the magnitude of the feed force can be measured, the forming tool (2) and the workpiece (5) being loaded with feed force relative to one another by means of the forming drive (3) while forming the workpiece (5),

a comparison unit (18) by means of which the magnitude of the feed force measured by the force measuring device (16) and a defined limit value for the magnitude of the feed force can be compared, the forming tool (2) and the workpiece (5) being loaded with feed force relative to one another by means of the forming drive (3) while forming the workpiece (5), and

a control unit (19), by means of which the motor-driven forming drive (3) can be actuated when the measured magnitude of the feed force reaches or exceeds a defined limit value for the magnitude of the feed force in such a way that the forming drive (3) moves the forming tool (2) and the workpiece (5) relative to one another over a return length in a return stroke after a partial forming stroke is carried out over a portion of the forming length and over another forming-partial length in another forming-partial stroke after the return stroke towards one another.

2. The device according to claim 1, characterized in that the control device (20) for the forming drive (3) has an evaluation unit (17) which is connected to the force measuring device (16) and by means of which evaluation unit (17) of the control device (20) a limit value for the magnitude of the feed force can be defined as a function of the magnitude of the feed force measured by means of the force measuring device (16), with which feed force the forming tool (2) and the workpiece (5) are loaded toward one another by means of the forming drive (3) while forming the workpiece (5).

3. The apparatus according to claim 1 or 2, characterized in that it is configured as an apparatus for shaping the workpiece (5) by cold extrusion.

4. Device according to claim 1 or 2, characterized in that a digital control device is provided as the control device (20).

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