WO2001043915A1

WO2001043915A1 - Method and device for machining and producing elongated structured components and a flexible shaft produced therewith

Info

Publication number: WO2001043915A1
Application number: PCT/EP2000/012140
Authority: WO
Inventors: Eckhard Huber; Wilfried Lehmann; Helmut Lehmann
Original assignee: Sandvik Ab
Priority date: 1999-12-15
Filing date: 2000-12-02
Publication date: 2001-06-21
Also published as: DE19960331A1

Abstract

The invention relates to a method and device for machining and producing elongated structured components and a flexible shaft produced therewith. The inventive method has the following steps: Clamping one of the ends of the elongated workpiece (1); displacing the workpiece in the longitudinal direction thereof into a predetermined first longitudinal position; rotating the workpiece (7) around the longitudinal axis thereof into a desired machining position; advancing a machining tool in an essentially radial direction toward the workpiece; supporting the workpiece on the side thereof located opposite the machining tool, and; retracting the machining tool into an initial position. The inventive method enables the production and machining of elongated structured workpieces in a distinctly simplified production process.

Description

Method and device for processing and producing elongated, structured components and flexible shaft produced therewith

The present invention relates to a method and a device for processing and producing elongated, structured components, and to a flexible shaft produced therewith.

In the prior art, there are a large number of elongated, structured objects, such as, for example, spindles, toothed racks or also flexible shafts. The method and the corresponding device from which the present invention is based relate in particular to the production of flexible shafts. However, the method according to the invention and the corresponding device can also be used without difficulty for the production of other elongated and structured objects. For example only and by way of illustration, the scope of the present invention therefore essentially refers to a specific type of flexible shaft which is produced using corresponding methods and devices.

In particular, the present invention also relates to a corresponding flexible shaft itself, which is produced using the method according to the invention and the corresponding device.

Such a flexible shaft is used above all in the medical field and is intended to be used to move a processing tool on paths that are not exactly straight through the human body, in particular in the longitudinal direction through the large limb bones, such as for example the thigh and lower leg bones or the upper arm bones. pass therethrough. Appropriate surgical measures are often necessary to heal broken bones or to anchor artificial components, such as brackets or screws, and in particular artificial joints in bones. For this purpose, a guide wire or catheter is generally introduced into the inside of the bone on the desired path and the processing tool, which has a corresponding central bore for the guide wire at its tip and which is located at the front end of a rotatable and flexible shaft, is placed on the guide wire pushed on and moved by this on a corresponding track.

With waves of this kind, it is particularly important to maintain hygienic conditions, but at the same time it is also extremely difficult. It is understood that such a tool, after being used on a patient, must be thoroughly cleaned and disinfected. must be decorated before it can be used again for another patient. Conventional flexible shafts, which essentially consist of a series of overlapping and mutually anchored but not separable rings or of coiled spirals, are largely unsuitable for this. Bone, bone marrow, blood or other tissue components that are difficult to remove and difficult to disinfect can accumulate in the narrow gaps between the rings or successive coils of spirals. If such components of foreign body tissue are inadvertently entered into the bones or bone marrow of another patient, there is a risk of the most serious infections and immune reactions, which in extreme cases can lead to the loss of the affected limbs or even death.

Therefore, other flexible shafts have been developed that are much easier to clean. These flexible shafts essentially consist of a tube into which a multiplicity of parallel slots are made in the circumferential direction, with successive slots being offset relative to one another in the circumferential direction and with each of the slots over an angular range of more than 180 ° and up to extends the order of 270 °. In practice, the slots are usually offset by approximately 120 ° in the circumferential direction relative to the preceding or following slot, so that the tube has essentially three different groups of slots, the slots of each group extending over the same angular range and different groups are each offset by 120 ° to each other, and in the order of the slots a slot from a first group is followed by another from the second group and preceded by a slot from the third group.

Of course, it is possible to choose other sequences of slots and the displacement in the circumferential direction does not necessarily have to be carried out by 120 ° in each case, but this form of corresponding flexible shafts has proven itself for the stated purpose, since in this way on the one hand a sufficient Flexibility of a pipe is achieved, but on the other hand the continuous slits are much easier to clean than alternately overlapping sheet metal rings or spirally wound strips.

It is understood that the more flexible the shaft, the greater the circumferential angle over which the slots extend and the wider the slots and the smaller the distance between the individual slots.

The slots are generally made by sawing or milling. However, this has the disadvantage that there are often burrs, in particular on the edges and at the ends of the slots, which are not always noticed and on which, when used as intended, need the wave to accumulate the material through which the wave is passed, in the above example in particular bone marrow or bone cells.

For this reason, complex post-processing of corresponding waves by blasting or grinding the surfaces is often necessary, in particular deburring the inner surface of such a wave is relatively complex and difficult. The inner side and end faces of the individual slots are not always sufficiently well covered.

Sawing or milling the individual slots in conventional machining centers is also a relatively complex and lengthy process.

Compared to this prior art, the present invention is based on the object of creating a method and a device for producing and processing elongated, structured workpieces and an object produced therewith, which enable a significantly simplified manufacturing process.

With regard to the method according to the invention, this object is achieved by a method which has the following steps: a) clamping one of the ends of the elongated workpiece, b) moving the workpiece in its longitudinal direction into a predetermined first longitudinal position, c) rotating the workpiece about its longitudinal axis into a desired machining position, d) feeding a machining tool towards the workpiece essentially in the radial direction, e) supporting the workpiece on the side of the workpiece opposite the machining tool at least during machining by the machining tool, f) retracting the machining tool into a starting position, g) repeating steps b to f until machining has taken place at all desired positions of the elongated workpiece and h) wherein steps b and c are also interchangeable or can be carried out simultaneously.

With regard to the corresponding device, the object on which the invention is based is achieved in that the device has the following features: a) a clamping device (2) for clamping one of the ends of the elongated workpiece, b) a feed device (3) for a feed movement of the clamped workpiece into a desired axial position, c) a rotating device (4) for rotating the elongated workpiece about its longitudinal axis (5), which is essentially parallel to the feed direction, and for holding the workpiece (1) in a desired rotational position, d) a processing device (6) with a processing tool (7 ), which can be adjusted essentially in the radial direction with respect to the axis of the workpiece (1) and e) a support device (8) for the workpiece (1), which is essentially on the side of the workpiece (1) opposite the machining device (6) is arranged.

A special object produced with such a method and a corresponding device is a flexible shaft made of a tube with slots, as has already been described above, the slots being produced by a suitable processing tool with a device according to the invention, in particular by grinding.

The method according to the invention and the corresponding devices allow an elongated object to be clamped at only one end, a corresponding feed device ensuring that it is moved into a desired first axial position and also rotated into a desired rotating position with the aid of a rotating device is, whereupon a processing tool is fed radially in the given position. This machining tool then engages the workpiece from one side and produces the desired structure, it also being possible for a certain axial advance of the workpiece to take place in both directions of the longitudinal axis of the workpiece and also for the rotational position of the workpiece also during the Processing can be varied more or less in order to carry out the processing on a corresponding circumferential section. The support device ensures that the workpiece can practically not deflect when the processing tool engages the workpiece from the opposite side. After the workpiece has been machined, the machining tool is withdrawn again in a predetermined section, and the workpiece is fed without machining into a desired new axial position in which, after the desired rotational position has been set appropriately, the machining tool can be re-engaged , All feed and rotary movements are preferably carried out with the aid of a numerically controlled machine tool, so that the individual feed and rotary movements take place very quickly and very precisely. The order of the feed and rotary movements is generally not important.

In the preferred embodiment of the invention it is provided that a tube, in particular a stainless steel tube, is used as the workpiece. A flexible shaft can be produced from such a tube by appropriate structuring, that is to say by introducing slots. A method is particularly preferred in which the machining by Grinding takes place and, accordingly, a device is preferred in which the processing tool is a grinding tool, in particular a rotating grinding wheel, which is fed with its circumferential edge in the radial direction to the workpiece. The machining tool in the form of the grinding wheel can also be rotated about an axis that runs parallel to the feed and return movement or direction. Closing the edge of a grinding wheel causes a slot in the thickness of the grinding wheel to be ground into a corresponding pipe or other elongate object. The extent of the feed movement of the tool when it is fed onto the workpiece determines the depth of the slot and thus also the circumferential angle over which the slot extends if the workpiece is not additionally rotated. In the preferred embodiment of the invention, the grinding wheel moves so far into the workpiece that there is a slot which extends over approximately 180 ° with respect to the axis of the workpiece. The workpiece can then be rotated in one or both directions by an angle of, for example, 30 ° to 90 °, which results in a correspondingly larger circumferential extent of the ground slot.

After the completion of the slot, the grinding wheel is pulled back into its starting position so that the workpiece can be advanced in order to be able to make another slot at a new axial position of the tube or generally to carry out further processing at a different axial position of the workpiece to be able to make.

In addition, however, it is also possible to carry out a limited feed movement of the workpiece while the grinding wheel is still in engagement with the workpiece, for example to increase the width of a slot.

The support device on the side opposite the processing tool, and expediently at a very close axial distance from the engagement position of the tool, prevents the workpiece from evading in the lateral direction and enables precise work and manufacture of corresponding structures or slots.

The support device can be stationary, but optionally also adjustable, in order to be able to adapt to different workpieces and also to different processing tools, since the processing by the support device should not be obstructed or disturbed if possible. It is of course expedient if the support takes place as close as possible to the area where the machining tool also acts, in order to be able to intercept the forces occurring as well as possible and without disturbing workpiece movements. The support device can also be divided and arranged at two different axial positions, close to and close to the engagement position of the machining tool. The structuring of the objects with the aid of a grinding process or a grinding tool or a grinding wheel has the particular advantage that in general no post-processing of the workpiece is required anymore and that the structures on the workpiece are produced essentially without burrs, so that post-processing generally does not more are required or can have a much smaller scope than in the manufacture of the structures by milling or sawing. The grinding wheel preferably has a thickness between 0.3 and 2 mm, so that accordingly there are also slots with a width between 0.3 and 2 mm. The slots are preferably made with a width of approximately 1 mm and they should run essentially parallel to one another and extend in the circumferential direction of the tube over an angle of more than 180 °. The repetition distance of successive (albeit offset in the circumferential direction) slots should be in the order of 1 to 5 mm, but can also be larger if the flexible shaft has a larger diameter of, for example, more than 8 or 10 mm. The combination of the repetition distance of the slots and slot width ultimately determines the smallest possible bending radius of such a shaft. The larger the slot width and the smaller the repetition distance, the smaller the bending radius can be. However, the stability of the shaft also decreases the smaller the minimum bending radius. The greatest possible circumferential extension of the slots reduces the bending stiffness, but also the stability of the shaft, so that sensible compromises are necessary.

In a particularly preferred embodiment of the invention, the machining tool is rotatably mounted about an axis parallel to its feed movement, which means, for example in the case of a grinding wheel which is fed with its edge, that the plane of the grinding wheel is 90 ° with respect to the axis of the workpiece is inclined at different angles. This angle of inclination should preferably be in the range between 60 ° and 85 °. In the case of the flexible shaft mentioned above, it can be used to produce slots which, in addition to their extension in the circumferential direction, also have an axial component. This axial component can be selected or adjusted in relation to the intended direction of rotation of the shaft in such a way that the slots at a rotational movement of the shaft material, which may accumulate in the tube or the shaft, preferably in a direction away from the front end of the shaft. In addition, it is of course also possible to make the grinding wheel slightly conical in its edge region, so that the side surfaces of the slots are also slightly conical or the width of the slots increases towards the outside.

The shafts can be produced very quickly and efficiently with the method according to the invention and the corresponding device, they require little or no post-processing and have extremely favorable properties in use. Further advantages, features and possible uses of the present invention are clearly evident the following description of a preferred embodiment and the associated figures. Show it:

FIG. 1 shows a plan view of a processing device for pipes according to the invention for producing flexible shafts,

Figure 2 is a side view of the device of Figure 1 and

Figure 3 shows schematically different processing stages in the manufacture of a flexible shaft from a tube with the device shown in Figures 1 and 2.

One can see in FIG. 1 a workpiece in the form of a tube 1, which is held with one of its ends in a clamping device 2, while the other end of the tube protrudes freely from the clamping device.

The clamping device is in turn mounted on a feed device 3 which is mounted on rails 13 in the direction of a Z-axis indicating the feed direction for the tool. In addition, the tensioning device 2 can also be rotated with the aid of a rotation device 4, the rotation device 4 being able to set any fixed rotational positions.

The rotation device 4 comprises a shaft 14 which can be displaced in the direction of the Z axis, that is to say in the direction of the rotation axis, which is in turn connected to the rotatably mounted tensioning device 2. The axis of the ball screw of the Z axis coincides with the axis of the tube 1 accommodated in the clamping device 2, so that the tube 1 can be rotated about its longitudinal axis, which is referred to here as the C axis.

Furthermore, one can see in FIG. 1 a processing tool in the form of a grinding wheel 7, which is attached to a corresponding grinding machine so as to be rotatable about its axis of symmetry, the grinding machine as a whole being movable in the direction of an X axis, which is at right angles to the C axis of the tube 1 runs.

A support device 8 in the form of a slide block is arranged opposite or slightly set back from the peripheral edge of the grinding wheel 7 and has either a bore or a partially cylindrical concave support surface for the tube 1. In the side view according to FIG. 2, it is also indicated schematically that the grinding spindle 6 can be pivoted about a pivot axis running through the center of the grinding wheel 7 and parallel to the X axis, essentially by an angle between ± 30 °.

The mode of operation of the device according to the invention can best be seen from the various processing stages which are shown in FIG. 3 in stages a, b and c. In processing stage a, the clamping device 2 can be seen, which has one end of a ground tube 1 holds. The feed device 3 has advanced the tube 1 so far that its free end protrudes somewhat beyond the support device 8 and rests with its side opposite a grinding wheel 7 in a corresponding guide surface of the support device 8. Now the grinding wheel 7 is fed in the direction of the Z axis and radially to the C axis of the pipe 1, whereby a slot extending in the circumferential direction of the pipe is ground into the pipe wall. The edge of the grinding wheel is moved so far into the tube that the slot extends at least over 180 °, possibly also about 270 ° or even more degrees with respect to the tube axis C. If necessary, even after a partially simple edge of the grinding wheel 7 in the tube 1, the tube can be rotated about the axis C by means of the rotation device 4 by a small angle of, for example, ± 60 °, around the slot in the circumferential direction of the tube to expand a desired dimension. Subsequently, the grinding wheel 7 is moved back into the position recognizable in the partial picture A and the feed device 3 moves the clamping device 2 and thus also the tube 1 forward by one step, which corresponds to the repetition distance of the slots. The rotation device 4 rotates the tube or before or after it by an angle which corresponds to the angular offset of successive slots. Then a slot is ground into the tube 1 again in the manner already described. This process is repeated, the tube being rotated through a predetermined angle before the next slot is made. In the present case, the tube for the production of the next slot is rotated through 120 °, so that there are a total of 3 different positions of the individual slots in the circumferential direction with respect to the C axis of the tube, with which three different slot groups are formed, as is the case with can be seen in the sub-images b and c, which show different stages of the manufacturing process, in stage c almost all the slots are produced which are required for the flexible shaft in question.

To increase the stability of the grinding wheel 7, only its radially outermost region T is set to the narrow slot width, while the radially further inside grinding wheel region is significantly thicker, a conical transition 16 being provided between the narrow outer region and the thicker inner region. If necessary, this conical area can be placed or the radial extent of the narrower area can be limited so that one side surface of the slots is still covered by the conical area during slot production, so that a slightly conical sloping wall results. This can further improve the transport of material through the shaft as it rotates and the cleanability of the shaft. It goes without saying that corresponding conical flanks can be provided on both sides of the grinding wheel. In addition, as can be seen from FIG. 2, the plane of the grinding wheel can be tilted out of its position perpendicular to the C-axis of the tube 1 by a pivot axis 11 so that the slots thus produced have a corresponding inclination relative to the axis of the tube could. Depending on the engagement position of the grinding wheel, that is, depending on whether the middle rich, the lower or upper area of the grinding wheel engages with the pipe, slit profiles can be generated if necessary, which have either a constant or a varying inclination relative to the pipe axis C.

The particular advantage of producing the slots with the aid of a grinding wheel and the device according to the invention with corresponding adjustment and support possibility of the tube 1 lies in a practically burr-free production of the slots, which requires little or no reworking of the flexible shaft.

Reference list

I tube / workpiece 2 clamping device

3 feed device

4 rotation axis / rotating device

5 pipe axis /

6 Machining device / grinding spindle 7 Machining tool / grinding wheel

8 support device

9 slots

I I swivel axis 13 rails 14 ball screw of the Z axis

16 conical transition

Claims

Patent claims

1. A method for machining and / or producing elongated, structured workpieces with the steps: a) clamping one of the ends of the elongated workpiece, b) moving the workpiece in its longitudinal direction into a predetermined first longitudinal position, c) rotating the workpiece about its longitudinal axis in a desired machining position, d) feeding a machining tool towards the workpiece essentially in the radial direction, e) supporting the workpiece on the side of the workpiece opposite the machining tool at least during machining by the machining tool, f) retracting the machining tool in a starting position and g) repeating steps b to f until machining has taken place at all desired positions of the elongated workpiece, h) steps b and c also being interchangeable or executable simultaneously.

2. The method according to claim 1, characterized in that a tube, in particular a stainless steel tube is used as the workpiece.

3. The method according to any one of claims 1 or 2, characterized in that the workpiece is processed by grinding, in particular by a rotating grinding wheel supplied with a peripheral edge at a right angle to the longitudinal axis of the workpiece.

4. The method according to any one of claims 1 to 3, characterized in that the machining tool is set in a rotational position changeable with respect to an axis of rotation parallel to the infeed axis (X).

5. Device for producing and / or machining elongated, structured workpieces, with: a) a clamping device (2) for clamping one of the ends of the elongated workpiece, b) a feed device (3) for a feed movement of the clamped workpiece Desired axial position, c) a rotating device (4) for rotating the elongated workpiece about its longitudinal axis (Z), which is essentially parallel to the feed direction, and for holding the workpiece (1) in a desired rotational position, d) a machining device (6) with a machining tool (7), which can be adjusted with respect to the axis of the workpiece (1) essentially in the radial direction and e) a support device (8) for the workpiece (1), which is essentially on the the machining device (6) opposite side of the workpiece (1) is arranged.

6. The device according to claim 5, characterized in that the support device (8) of the machining device (6) is arranged directly opposite on substantially the same axial length of the workpiece on which the machining tool (7) engages.

7. The device according to claim 5 or 6, characterized in that the support device is designed as a fixed with respect to the machining tool (7) or movable in the longitudinal direction slide block with a partially cylindrical, concave support surface.

8. Flexible shaft (1) consisting of a tube which has a series of slots, thereby increasing the flexibility of the tube, characterized in that the slots (9) are made by grinding.

9. Flexible shaft according to claim 8, characterized in that the width of the slots between 0.3 and 2 mm, preferably about 1 mm, that the slots (9) substantially parallel to the tube over a circumferential angle of more than 180 ° run, and that the repeat distance of the slots is in the range between 1 mm and 5 mm.

10. Flexible shaft according to claim 8 or 9, characterized in that the slots (9) with respect to the tube axis (5) are inclined, preferably with an inclination angle between 60 ° and 85 ° relative to the tube axis (5).