GRINDING METHOD AND GRINDING MACHINE

Abstract

In a method for circular grinding of a workpiece (14), in which a rotating grinding wheel (18) is positioned against a face (30) to be ground of the workpiece, while simultaneously the workpiece rotates about its longitudinal axis, and the face to be ground is defined by an edge (34) and merges with a neighboring face (36), the object is for the previously necessary deburring operation that was required following the grinding operation to be dispensed with. To that end, it is provided that a deburring mandrel (22) is pressed during grinding against the neighboring face (36), so that a burr (32) created in grinding the face to be ground is pressed back against this face. An apparatus with which this method can be performed is also described.

Description

PRIOR ART

[0001] The invention relates to a method for circular grinding of a workpiece, in which a rotating grinding wheel is positioned against a face to be ground of the workpiece, while simultaneously the workpiece rotates about its longitudinal axis, and the face to be ground is defined by an edge and merges with a neighboring face. The invention also relates to an apparatus for circular grinding of a workpiece, which has both a grinding wheel and a chuck for the workpiece to be ground.

[0002] During the grinding operation, a burr is created, which begins at the face to be ground and extends past the edge to the adjoining neighboring face of the workpiece. If this burr is problematic for the later function of the fully machined workpiece, it must be removed by a separate deburring operation.

[0003] The object of the invention is to improve the grinding method of the type defined at the outset in such a way that the deburring operation can be dispensed with. The object of the invention is also to create an apparatus for grinding that makes it possible to dispense with the separate deburring operation.

ADVANTAGES OF THE INVENTION

[0004] The method of the invention having the characteristics of claim 1 has the advantage that the burr created upon positioning of the grinding wheel against the face to be ground is automatically eliminated. A separate deburring operation is thus no longer necessary.

[0005] In a preferred embodiment of the invention, it is provided that the deburring mandrel is adjusted such that it protrudes outward past the neighboring face and the edge toward the face to be ground. In this orientation of the deburring mandrel, it is assured that the burr created upon grinding can be pressed all the way back against the face to be ground again.

[0006] Preferably, it is provided that the deburring mandrel is pressed onto the neighboring face with a force between 10 and 100 N, and in particular with a force on the order of magnitude of about 50 N. The forces named represent a good compromise between reliably pressing back the burr on the one hand and low frictional forces on the other.

[0007] The apparatus of the invention having the characteristics of claim 6 offers essentially the same advantages as explained above in conjunction with the method of claim 1. Since the burr is continuously ground off again by means of the grinding machine of the invention, a burr- free ground workpiece is the result, without a separate machining step adjoining the grinding operation.

[0008] In a preferred embodiment of the invention, a pneumatic cylinder is provided, which can press the deburring mandrel with an adjustable force against the workpiece to be machined. In this way, at little effort, the contact force between the workpiece and the deburring mandrel can be adjusted to given requirements.

DRAWINGS

[0009] The invention is described below with reference to various exemplary embodiments, which are shown in the accompanying drawings. Shown in them are:

[0010] FIG. 1, in a schematic elevation view, a grinding machine of the invention;

[0011] FIG. 2, on a larger scale, a detail of FIG. 1;

[0012] FIG. 3, an elevation view of the components shown in FIG. 2, seen in the direction of the arrow III of FIG. 2;

[0013] FIG. 4, a half section through the machined workpiece, taken along the plane IV of FIG. 3;

[0014] FIG. 5, a half section through the machined workpiece, taken along the plane V of FIG. 3;

[0015] FIG. 6, in an elevation view corresponding to that of FIG. 2, a second embodiment of the invention;

[0016] FIG. 7, in an elevation view corresponding to that of FIG. 4, a section through the workpiece of FIG. 6; and

[0017] FIG. 8, in an elevation view corresponding to that of FIG. 5, a further section through the workpiece of FIG. 6.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0018] In FIG. 1, a machine in accordance with a first embodiment of the invention is shown. The grinding machine includes a frame 10, in which a chuck 12 is disposed for a workpiece 14 that is to be machined. A drive 16 is provided, with which the workpiece 14 can be set into rotation. A grinding wheel 18 is also provided, which by means of a positioning drive 20 can not only be set into rotation by also positioned suitably against a face to be ground of the workpiece 14. The grinding machine described thus far is conventional in design, and so its construction need not be described in detail.

[0019] In addition, the grinding machine is provided with a deburring mandrel 22, which is of hard metal and can be pressed by a contact-pressure mechanism 24 against the workpiece 14 that is to be machined. The contact-pressure mechanism has a pneumatic cylinder 26 (see FIG. 2), whose interior can be subjected to pressure via two schematically shown pneumatic lines 28, in order to press the deburring mandrel 22 against the workpiece 14 in the direction of the arrow P of FIG. 2.

[0020] The mode of operation of the deburring mandrel is as follows: When the grinding wheel 18 is positioned against a face 30 to be ground of the workpiece 14 in the direction of the arrow Z of FIG. 2, the result is a burr 32 (see FIGS. 3 and 4), which comprises material that is positively displaced, via an edge 34 that defines the face 30 to be machined of the workpiece, onto an adjoining neighboring face 36.

[0021] Since the workpiece 14 is in rotation, the burr reaches the deburring mandrel 22, which in the embodiment shown is approximately opposite the grinding wheel 18. There, by means of the end face of the deburring mandrel 22, which is embodied as a plane contact-pressure face 38 and extends perpendicular to the longitudinal axis of the deburring mandrel and protrudes past the edge 34, the burr is pressed back onto the face 30 to be ground. This can be seen clearly from a comparison of FIGS. 4 and 5. FIG. 4 shows a section through a portion of the workpiece that has just been machined by the grinding wheel 18 and now rotates toward the deburring mandrel 22. The burr 32 is located outside the face 30 to be machined, in the region of the neighboring face 36 that adjoins the edge 34. In FIG. 5, a section through a portion of the workpiece can be seen that after being in contact with the end face of the deburring mandrel 22 moves back toward the grinding wheel 18 again. It can be clearly seen that the burr 32 has been pressed back onto the face 30 to be machined, so that upon the next contact with the grinding wheel 18, it will be ground off.

[0022] The contact-pressure force of the deburring mandrel 22 can be selected as a function of given requirements and of the material to be machined. For instance, if the workpiece 14 is a valve needle for a fuel injection valve for internal combustion engines, in which the face to be machined has a diameter of only a few millimeters, contact-pressure forces of 50 N are sufficient.

[0023] The cycle described here, of creating the burr by contact between the workpiece 14 and the grinding wheel 18, pressing the burr 32 back onto the face 30 to be machined, and grinding down the burr, is repeated until such time as the grinding wheel sparks out, or in other words no further material at all is being removed and consequently no burr can be created, either. The outcome of the grinding operation described is a workpiece 14 with a ground face 30 that has no burr, without a separate deburring operation having been necessary.

[0024] The arrangement shown here of the deburring mandrel 22 relative to the grinding wheel 18 can be varied to suit requirements. If a plurality of faces are ground simultaneously and if in addition measuring tools, for instance, monitor the grinding operation, then the deburring mandrel 22 can also be used in other positions relative to the grinding wheel.

[0025] In FIGS. 6-8, a second embodiment of the grinding machine and of the grinding method performed with it are shown. For the components already known from the first embodiment, the same reference numerals are used, and reference is made to the above explanations.

[0026] The most essential difference from the first embodiment is that here a cylindrical outer face of the workpiece 14 is ground, so that the burr 32 is created on a neighboring face 36, which adjoins the face 30 to be machined and which extends perpendicular to the longitudinal axis of the workpiece 14. From this neighboring face 36, the burr 32 is pressed back by the deburring mandrel 22 onto the face 30 to be ground again, as can be seen by a comparison of FIGS. 7 and 8.

[0027] In a distinction from the first embodiment, the deburring mandrel 22 in the second embodiment does not rest with its face end on the workpiece 14 but rather with a conically embodied contact-pressure face 38. In addition, the longitudinal axis of the deburring mandrel 22 is not oriented perpendicular to the longitudinal axis of the workpiece 14 but instead extends obliquely to it. It is especially important to note that the deburring mandrel 22 is not pressed approximately in the direction against the workpiece 14 in-which the burr 32 is meant to be pressed back onto the face to be machined, but rather in a direction in which one would expect that the burr would be pressed back inward again toward the longitudinal axis of the workpiece. In fact, however, by means of the obliquely positioned contact-pressure face 38, the burr 32 is pressed back onto the face 30 to be ground, away from the longitudinal axis of the workpiece 14. The orientation shown here for the deburring mandrel 22 is especially advantageous if other components of the grinding machine have to be disposed in the region located to the left of the deburring mandrel 22, in terms of FIG. 6; in that case, the contact-pressure mechanism 24 can then be disposed far outside that region.

Claims

1. A method for circular grinding of a workpiece (14), in which a rotating grinding wheel (18) is positioned against a face (30) to be ground of the workpiece, while simultaneously the workpiece rotates about its longitudinal axis, and the face to be ground is defined by an edge (34) and merges with a neighboring face (36), characterized in that a deburring mandrel (22) is pressed during grinding against the neighboring face (36), so that a burr (32) created in grinding the face to be ground is pressed back against this face.

2. The method of claim 1, characterized in that the deburring mandrel (22) is adjusted such that it protrudes outward past the neighboring face (36) and the edge (34) toward the face (30) to be ground.

3. The method of claim 2, characterized in that the deburring mandrel (22) is adjusted such that it protrudes with approximately half its diameter past the neighboring face (36).

4. The method of one of claims 1-3, characterized in that the deburring mandrel (22) is pressed onto the neighboring face 36) with a force between 10 and 100 N.

5. The method of claim 4, characterized in that the deburring mandrel (22) is pressed onto the neighboring face (36) with a force approximately 50 N.

6. An apparatus for circular grinding of a workpiece (14), having a grinding wheel (18) and a chuck (12) for the workpiece (14) to be ground, characterized in that a deburring mandrel (22) is provided, which can be pressed onto a neighboring face (36) adjoining the face (30) to be ground of the workpiece.

7. The apparatus of claim 6, characterized in that the deburring mandrel (22) has a flat end face.

8. The apparatus of claim 6, characterized in that the deburring mandrel (22) has a conical contact-pressure face (38).

9. The apparatus of one of claims 6-8, characterized in that the deburring mandrel (22) is disposed such that longitudinal axis extends approximately at a right angle to the longitudinal axis of the workpiece (14) to be machined.

10. The apparatus of one of claims 6-8, characterized in that the deburring mandrel (22) is disposed such that its longitudinal axis extends at an angle other than 90° relative to the longitudinal axis of the workpiece (14) to be machined.

11. The apparatus of one of claims 6-10, characterized in that a pneumatic cylinder (26) is provided, which can press the deburring mandrel (22) with an adjustable force against the workpiece (14) to be machined.