EP1661638B1 - Method and device for precision rolling of rotationally symmetric workpieces - Google Patents

Description

The invention relates to a method and a device for precision rolling of rotationally symmetrical components. Thus, in particular profiled sections of the component are produced or reworked, z. B. by calibration. In the rotationally symmetric component, it may be z. B. to act worm wheels, injectors or fitting shaft sections. Preferably, it is a connecting element in the form of a screw. In the profiled section, it may, for. As a thread, a helix, a knurl, a groove profile, a screw profile or a gearing act. In addition to the production or reworking of profiled sections and the production or reworking of non-profiled sections is possible, in particular by smooth rolling the lateral surface of the component or workpiece.

In all these rolling process, the component to be machined is taken up between at least two spaced rolling tools and shaped according to their geometry. During the processing of the lateral surface of the component, the problem arises that the rolling tools are forced apart due to the opposing force exerted by the component. This leads in the prior art to the fact that the actual finished part diameter of the component of the desired target finished part diameter of the component partially deviates so much that the required process reliability is not achieved.

STATE OF THE ART

A device according to the preamble of claim 1 and a method according to the preamble of claim 7 for precision rolling the lateral surface of a rotationally symmetrical component with at least two spaced rolling tools and a Means for determining the actual raw part diameter of the component are known from DE 31 10 433 A1 known. The comparison of the actual raw part diameter of the component with a target raw part diameter of the component is used as a decision criterion for the respective statement "workpiece - good" or "workpiece - Committee".

A profile rolling machine for forming the lateral surface of rotationally symmetrical components is known from CH 692 382 A5 known. The profile rolling machine has a machine bed, are mounted on the guide rails for carriages. The carriages carry rolling tools in the form of rolling heads and are mounted so as to be displaceable along the guide rails so that the distance between the rolling tools can be adjusted by relative movement of the carriages relative to one another along the guide rails. The profile rolling machine also has a force frame with two end plates arranged yoke plates. The power frame is arranged so movable in the direction of movement of the carriage on the machine bed that the machine bed is decoupled from the power frame and thus should absorb the lowest possible rolling forces during forming of a component. The profile rolling machine has a length measuring device arranged on the machine bed with which the position of the movable slide relative to the machine bed can be measured. Further, a controller is provided which corrects the position of the rolling tools to each other in dependence on a possible elongation of the force frame. Overall, the known profile rolling machine is thus based on the concept of decoupling the machine base including the length measuring device from the power frame including the rolling tools in such a way that a readjustment of the distance between the rolling tools is possible depending on the distance between the rolling tools measured during the rolling process with the length measuring device ,

A method and an apparatus for burnishing rotationally symmetrical components are from the DD 288 787 A5 known. The NC machine tool in this case has a spring-loaded rolling tool in the tool holder, on the shaft of which a length measuring device with switching contacts is fastened. The length measuring device is connected to the control of the NC machine tool. The workpiece- and material-dependent rolling force is adjusted taking into account the spring characteristic of the rolling tool in the desired tolerance range in the length measuring device. The deformation of the spring element in the rolling tool during the rolling process is used as an indirect measure of the rolling force occurring and detected by the length measuring device. If the set tolerance range is exceeded Switching pulses triggered, which are used to control the rolling force. The aim is thus to achieve as constant as possible a rolling force independent of the blank geometry of the component.

OBJECT OF THE INVENTION

The invention has for its object to provide a method and apparatus for precision rolling the lateral surface of a rotationally symmetrical component on a rolling machine, with which an increased accuracy of the finished part geometry of the component is achieved.

SOLUTION

The object of the invention is achieved according to the invention with the features of the independent claims 1 and 7.

DESCRIPTION OF THE INVENTION

The inventive device for precision rolling the lateral surface of a rotationally symmetrical component has at least two spaced rolling tools. There is further provided a device for determining the actual raw part diameter of the component and a device for comparing the actual blank part diameter of the component with a predetermined blank diameter and for determining a correction value from the result of the comparison of the actual blank part diameter of the component with the predetermined blank diameter. A control is used to set the distance between the at least two rolling tools as a function of the correction value.

The device for determining the actual raw part diameter of the component may be a measuring device. However, it may also be a separate measuring device and an interface of the device to the separate measuring device. The device for comparing the actual raw part diameter of the component with a predetermined blank diameter and for determining a correction value from the result of the comparison of the actual blank part diameter of the component with the predetermined blank diameter may be an evaluation device. It can also be a separate evaluation and an interface of the device to the separate evaluation act. The device itself must therefore have no measuring device or evaluation. It merely has to be designed in such a way that data of a measuring device can be transmitted to an evaluation device and from this to the control of the device.

In the inventive method for precision rolling the lateral surface of a rotationally symmetrical component on a rolling machine with at least two spaced rolling tools, the actual raw part diameter of the component is first measured. Then, the actual raw part diameter of the component is compared with a predetermined Rohteildurchmesser and determines a correction value from the result of the comparison of the actual Rohteildurchmessers of the component with the predetermined Rohteildurchmesser. Thereafter, the distance between the at least two rolling tools is set in dependence on the correction value.

The invention is based on the finding that the previous attempts in the prior art to realize a constant distance between the rolling tools in terms of a nearly constant Bearbeitungsendposition the rolling machine and a high rigidity of the rolling machine, does not lead to the required accuracy of finished part diameter of the component , The invention deliberately starts from this concept and replaces it with a regulation of the distance between the rolling tools as a function of the result of the measurement of the actual raw part diameter of the component before it is processed.

This new concept of controlling the distance between the rolling tools as a function of a correction value based on the measured actual pipe diameter of the component is based, inter alia, on the following findings: when a batch of n components is to be precision rolled and m components thereof are an actual pipe diameter in the range Having the lower tolerance - so are relatively thin - you can observe that these m components have a smaller diameter after the precision rollers than the other thicker components. In other words, even after precision rolling, a thin component remains comparatively thin and a thick component remains comparatively thick. The diameters of the components remain approximately equal in relation to each other, with the scattering band in which the components are located being reduced by the precision rolling. This reduction of the scattering is z. B. at a scatter in the area of 0.1 mm, the blank diameter at less than about 0.02 mm, the finished part diameter of the components. This suggests that the elastic springing of the components increases during forming during rolling.

The evaluation device assigns the measured actual raw part diameter of the component to a defined group of a plurality of groups of predetermined raw part diameters, wherein each of the groups is assigned a specific correction value. This solution has the advantage that the control and adjustment effort is minimized with sufficient accuracy of finished part diameter of the components. This means that it is not necessary to approach a different position of the rolling tools for each component. The number and classification of the groups is dependent on the tolerance of the initial diameter and the permissible finished part diameter of the component. Alternatively, however, the correction value can also be determined according to a machine and material-specific mathematical function.

The evaluation device can determine the correction values on the basis of a comparison of the measured actual finished part diameter of a component with a predefined desired finished part diameter for each of the groups of predetermined blank part diameters. In other words, a characteristic of the respective rolling machine, the respective material and the respective geometry of the component is determined. For simplicity, the group division of the blank diameter is used.

The measuring device can, for. B. be arranged in an automatic feeding device for the components. So it is quite a structural and spatial separation of the measuring device of the actual device for precision rolling (rolling machine) possible. The measuring device does not have to be an immediate part of the device. It is only essential that the measuring device of the evaluation is assigned and connected to this for electronic transmission of the measurement data that the evaluation based on the measured data determine the correction value and can pass it to the controller for adjusting the distance between the at least two rolling tools. Accordingly, the evaluation device can be structurally and spatially separated from the device.

The measuring device may be a mechanical or optical measuring device. In the mechanical measuring device, the diameter of the component z. B. detected by a mechanical button. In the optical measuring device find, for example, photoelectric sensors or cameras use.

The component may be a connecting element, in particular a screw. In the case of screws, in particular the rolling of profiled sections is a particularly frequent application. Thus, the shank of a screw is partially cold formed by rolling to z. B. to create a thread, a helix in a fitting section or a knurl.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1

zeigt eine Prinzipdarstellung einer Vorrichtung zum Präzisionsrollen der Mantelfläche eines rotationssymmetrischen Bauteils.

Fig. 2

zeigt ein Kraft-Weg-Diagramm.

Fig.3

zeigt ein schematisches Blockdiagramm einer ersten Ausführungsform der neuen Vorrichtung zum Präzisionsrollen der Mantelfläche eines rotationssymmetrischen Bauteils.

Fig. 4

zeigt ein schematisches Blockdiagramm einer zweiten Ausführungsform der neuen Vorrichtung zum Präzisionsrollen der Mantelfläche eines rotationssymmetrischen Bauteils.

Fig. 5

zeigt ein schematisches Blockdiagramm einer dritten Ausführungsform der neuen Vorrichtung zum Präzisionsrollen der Mantelfläche eines rotationssymmetrischen Bauteils.

Fig. 6

zeigt ein Diagramm der Rohteildurchmesser über den Fertigteildurchmessern für das neue Verfahren im Vergleich zum Stand der Technik.

Fig. 7

zeigt eine Prinzipdarstellung einer weiteren Vorrichtung zum Präzisionsrollen der Mantelfläche eines rotationssymmetrischen Bauteils.

Fig. 8

zeigt eine Prinzipdarstellung einer weiteren Vorrichtung zum Präzisionsrollen der Mantelfläche eines rotationssymmetrischen Bauteils.

In the following the invention will be further explained and described with reference to preferred embodiments shown in the figures.

Fig. 1

shows a schematic diagram of an apparatus for precision rolling the lateral surface of a rotationally symmetrical component.

Fig. 2

shows a force-displacement diagram.

Figure 3

shows a schematic block diagram of a first embodiment of the new device for precision rolling the lateral surface of a rotationally symmetrical component.

Fig. 4

shows a schematic block diagram of a second embodiment of the new device for precision rolling the lateral surface of a rotationally symmetrical component.

Fig. 5

shows a schematic block diagram of a third embodiment of the new device for precision rolling the lateral surface of a rotationally symmetrical component.

Fig. 6

shows a diagram of the raw part diameter over the finished part diameters for the new method compared to the prior art.

Fig. 7

shows a schematic diagram of another device for precision rolling the lateral surface of a rotationally symmetrical component.

Fig. 8

shows a schematic diagram of another device for precision rolling the lateral surface of a rotationally symmetrical component.

DESCRIPTION OF THE FIGURES

Fig. 1 shows the basic structure of a device 1 for precision rolling the lateral surface 2 of a rotationally symmetrical component 3. The device 1 has two spaced rolling tools 4, 5. Furthermore, a support 6 is provided which serves to support the component 3. The rolling tools 4, 5 have one of the geometry to be generated of the lateral surface 2 of the component 3 corresponding shape. The rolling tools 4, 5 are driven in the same direction according to the arrows 7, 8 by means of a drive, not shown. At least one of the rolling tools 4, 5 is arranged such that the distance between the rolling tools 4, 5 is adjustable. It is also possible that both rolling tools 4, 5 are arranged so movable. The arrangement of three rolling tools, between which the component is included, is possible. The workpiece support 6 can except in the illustrated fixed shape to increase the processing speed as a movable support z. B. be executed in the form of a roll cage. The basic mode of operation of the device 1 or a rolling machine is well known from the prior art and will therefore not be further described herein. The new aspects of the operation of the device 1 will be described in particular with reference to FIGS. 3 to 6.

FIG. 2 shows a force-displacement diagram for clarifying the findings on which the invention is based. In the diagram, the change in diameter or displacement S of a component is plotted as a function of the force F applied by the rolling tools 4, 5. The machined component consists of a material without a pronounced yield strength. The diagram shows that the component at a deformation below the yield strength R _e or Rp after the discharge according to the Hooke Just spring back elastically to the original size. However, if the component is loaded beyond Rp, plastic deformation will occur. Since the modulus of elasticity of a material is constant, the elastic recovery takes place in accordance with Hooke's straight line. For point 1 marked in FIG. 2, this means that the elastic springback referred to as S _el1 occurs. If a component is loaded to the point 2 and springs back according to the Hooke's straight line by S _el2 , it can be seen that the amount of springback S _{el2 differs} by ΔS _el .

Applied to the method of precision rolling (FIG. 1), this means the following: a first component 3 with a first blank diameter is elastically plastically deformed in the apparatus 1 by means of the rolling tools 4, 5 until the point 1 is reached and elastically springs after the relief by the amount S _el1 back. If now a second component 3 with a larger blank diameter in the device 1 by means of rolling tools 4, 5 in the same position elastically-plastically deformed, occurs a higher forming force according to point 2. The elastic springback S _el2 is greater by the amount ΔS _el than the springback S _{el1 of} the first component 3 with a smaller raw part diameter. Correspondingly, the finished part diameter of the second component 3 is greater than that of the first component 3 by ΔS _el . It can therefore be seen that different finished part diameters occur at different blank diameters, independently of the realized rigidity of the device 1, if the same relative position of the rolling tools 4, 5 are maintained relative to one another becomes. The present invention is based on this finding.

The new control principle of the device 1 and the method performed therewith for precision rolling the lateral surface 2 of a rotationally symmetrical component 3 will be described in more detail below with reference to FIG. 3 . The device 1 has a measuring device 9 for measuring the actual raw part diameter of the component 3. The measuring device 9 is connected to an evaluation device 10. The evaluation device 10 is used to compare the measured actual Rohteildurchmessers of the component 3 with a predetermined Rohteildurchmesser and for determining a correction value from the result of the comparison of the actual Rohteildurchmessers of the component 3 with the predetermined Rohteildurchmesser. The evaluation device 10 is in turn connected to a controller 11. The controller 11 is used to set the distance between the rolling tools 4, 5 in dependence on the correction value.

But it is also possible that the actual device 1 structurally and spatially separated from the measuring device 9 and / or formed by the evaluation device 10. In this case, the device 1 or its controller 11 has corresponding interfaces. The measuring device 9 does not have to be an immediate component of the device 1. All that is essential is that the measuring device 9 of the evaluation device 10 is associated with and connected to the electronic transmission of the measurement data that the evaluation device 10 based on the measured data determine the correction value and the controller 11 for adjusting the distance between the at least two rolling tools. 4 , 5 can pass.

A first such embodiment is shown in Fig. 4 schematically. The controller 11 has as an apparatus 12 an interface 13 to the measuring device 9 and as a device 14 an interface 15 to the evaluation unit 10. It is understood that Fig. 4 does not reflect the exact electronic connection of the individual components, but only the logical assignment.

Another example is shown schematically in FIG . The device 1 or its controller 11 has a device 12 as an interface 13 to the measuring device 9. The device 14 is integrated here in the controller 11, so that the interface 15 is preferably designed as a software interface.

Preferably, a component-related characteristic in the respective device 1 is first determined by carrying out the forming process without varying the distance between the rolling tools 4, 5. For this purpose, components 3 of different raw part diameters in the device 1 are processed by rolling and the resulting prefabricated part diameters are measured and determined by means of a measuring device. From the deviations from the target finished part diameter diameter correction values are then determined. It has proved to be advantageous to divide the different raw part diameters into several diameter classes and to assign a different correction value to each diameter class. Depending on the permissible tolerance width for the finished part diameter in relation to the tolerance width of the blank part diameter, the blank part diameter is divided into more or less many classes. For example, you will form a larger number of classes in a large fluctuation of the Rohteildurchmessers and / or a tight tolerance of the finished part diameter.

As finished part diameter, preferably the outside diameter of the finished part is measured. Depending on the requirements of the component but is also possible to make the measurement at another point of the component 3 and, for example, to use the pitch diameter or the core diameter of a thread or a profile of the component 3.

By deliberately controlling the distance between the at least two rolling tools 4, 5 as a function of a correction value developed from the blank part diameter, it is possible to allow larger tolerances of the blank part diameter, since the never reducible to zero elasticity of the device 1 are almost completely compensated by the control process can. Furthermore, it is conceivable to omit comparatively complicated stiffening or decoupling measures of the device 1, which reduces the costs for the usual components of the device 1.

The advantages achieved in comparison with the prior art with the invention can be seen particularly well in the diagram according to FIG . In Fig. 6 the blank part diameter of the component 3 is applied over the finished part diameter. In the case of the line marked "state of the art", it can be seen that the diameter of the finished part increases as the diameter of the blank increases, increasing approximately linearly with a relatively large gradient. This undesirable effect is substantially reduced by means of the invention, as can be clearly seen from the second line marked "Invention".

In this way, it is now possible to achieve high accuracies of the prefabricated part diameter of the component 3 with comparatively large fluctuations of the blank part diameter without particular measures relating to the rigidity of the device 1. Thus, the requirements of process safety are taken into account. For example, with an outer diameter of the component 3 of 22 mm, an accuracy of ± 10 μm of the finished part diameter of the component 3 can be achieved. With an outer diameter of the component 3 of 8.5 mm, even an accuracy of ± 5 microns of the finished part diameter of the component 3 can be achieved reliably.

Fig. 7 shows the basic structure of another device 1 for precision rolling the lateral surface 2 of a rotationally symmetrical component 3 in the form of a screw. The device 1 has in this case as rolling tools 4, 5 profiled flat jaws 16, 17, of which the movable flat jaw 16 relative to the stationary flat jaw 17th translationally to generate the thread of the screw is moved. The distance between the flat jaws 16, 17 perpendicular to the direction of movement is varied by means of the control according to the invention.

Fig. 8 shows the basic structure of another device 1 for precision rolling the lateral surface 2 of a rotationally symmetrical component 3 in the form of a screw. The device 1 has in this case as rolling tools 4, 5 a profiled segment 18 and a profiled roller 19, of which the roller 19 is moved relative to the stationary segment 18 according to arrow 20 rotationally for generating the thread of the screw. The distance between the roller 19 and the segment 18 is varied by means of the control according to the invention.

LIST OF REFERENCE NUMBERS

1

contraption

2

lateral surface

3

component

4

roll tool

5

roll tool

6

edition

7

arrow

8th

arrow

9

measuring device

10

evaluation

11

control

12

Facility

13

interface

14

Facility

15

interface

16

flat shoe

17

flat shoe

18

segment

19

role

20

arrow

Claims (10)

1. An apparatus for precision rolling of a surface area of a rotationally symmetrical component, comprising
   at least two spaced apart rolling tools (4, 5);
   a unit (12) for determining an actual blank diameter of the component (3),
   characterised by
   a unit (14) for comparing the actual blank diameter of the component (3) with a predetermined blank diameter and for determining an adjustment value from the result of the comparison of the actual blank diameter of the component (3) with the predetermined blank diameter, wherein
   the unit (14) is designed as an evaluating unit (10) or as a separate evaluating unit (10) and an interface (15) to the separate evaluating unit (10), and
   the evaluating unit (10) is designed to associate the determined actual blank diameter of the component (3) to a specific group of a plurality of groups, each of the groups containing a specific adjustment value; and
   a control unit (11) for adjusting the distance between the at least two rolling tools (4, 5) in response to the adjustment value.
2. The apparatus of claim 1, characterised in that the unit (12) for determining the actual blank diameter of the component (3) is designed as a measuring unit (9).
3. The apparatus of claim 1, characterised in that the unit (12) for determining the actual blank diameter of the component (3) is designed as a separate measuring unit (9) and an interface (13) to the separate measuring unit (9).
4. The apparatus of at least one of claims 1 to 3, characterised in that the evaluating unit (10) determines the adjustment values based on a comparison of the determined actual finished part diameter of a component (3) with a predetermined desired finished part diameter for each one of the groups of predetermined actual blank diameters.
5. The apparatus of at least one of claims 2 to 3, characterised in that the measuring unit (9) is located in an automatic feeding unit for the components (3).
6. The apparatus of at least one of claims 2, 3 or 5, characterised in that the measuring unit (9) is designed as a mechanical measuring unit or an optical measuring unit.
7. A method of precision rolling of a surface area of a rotationally symmetrical component in a rolling machine including at least two spaced apart rolling tools, said method comprising the steps of:

   determining an actual blank diameter of the component (3);

   comparing the actual blank diameter of the component (3) with a predetermined blank diameter, characterised by the steps of

   determining an adjustment value from the result of the comparison of the actual blank diameter of the component (3) with the predetermined blank diameter, the actual blank diameter of the component (3) being associated with a specific group of a plurality of groups of predetermined actual blank diameters, each of the groups being associated with a specific adjustment value; and

   adjusting the distance between the at least two rolling tools (4, 5) in response to the adjustment value.
8. The method of claim 7, characterised in that the adjustment values are determined based on a comparison of the measured actual finished part diameter of the component (3) with a predetermined desired finished part diameter for each one of the groups of predetermined actual blank diameters.
9. The method of claim 7 or 8, characterised in that the component (3) is a fastener, especially a screw.
10. The method of claim 9, characterised in that a profiled section of the fastener is produced by rolling.

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