Truing Device

Abstract

A truing device for truing a grinding tool having a specified grinding profile, includes at least one first truing region and a second truing region connected thereto. The first truing region has a first specification for sharpening the grinding profile of the grinding tool and the second truing region has a second specification, different from the first specification, for restoring the grinding profile of the grinding tool. The first truing region has a greater volume than the second truing region, the truing device has a longitudinal axis, the two truing regions are arranged one behind the other in the direction of the longitudinal axis, and the truing device is substantially cuboid.

Description

BACKGROUND OF THE INVENTION

[0001] The invention concerns a dressing apparatus for dressing a grinding tool provided with a predetermined grinding profile and a method of dressing a grinding tool by means of at least one such dressing apparatus.

[0002] Grinding tools have to be dressed after a given period of time in grinding operation, in which respect a number of processes are distinguished from each other in terms of the dressing operation.

[0003] One of those processes involves sharpening the grinding profile of the grinding tool. In that procedure for example impurities are removed, abrasive grains which have become blunt are removed, fresh abrasive grains are exposed and/or abrasive grains are sharpened, for example by breaking them.

[0004] A further process involves restoring the grinding profile of the grinding tool. In the course of that process binder material, grinding deposits and/or abrasive grains are removed, with the aim of restoring the predetermined grinding profile of the grinding tool.

[0005] Dressing tools with a unitary specification which is based on a compromise between the different dressing processes are known from the state of the art.

[0006] That has a detrimental on the maximum operating lifetime of the grinding tool, that is to say the period of time between the first-off use of the grinding tool and the time at which the grinding profile of the grinding tool is damaged to such an extent that the grinding tool has to be returned to the manufacturer in order to mechanically reconstruct the original grinding profile, preferably by electrical discharge machining.

SUMMARY OF THE INVENTION

[0007] The object of the present invention is to provide a dressing apparatus which is improved over the state of the art and which permits in particular an increased operating lifetime of the grinding tool dressed by the dressing apparatus. A further object is that of providing a method of dressing a grinding tool by means of at least one such dressing apparatus which permits in particular efficient dressing of a grinding tool and an increased operating lifetime of the grinding tool.

[0008] In the dressing apparatus according to the invention it is therefore provided that the dressing apparatus includes at least a first dressing region and a second dressing region connected thereto, wherein the first dressing region has a first specification for sharpening the grinding profile of the grinding tool and the second dressing region has a second specification differing from the first specification for restoring the grinding profile of the grinding tool, the first dressing region is of a larger volume than the second dressing region, the dressing apparatus has a longitudinal axis, the two dressing region are arranged in succession in the direction of the longitudinal axis and the dressing apparatus is of a substantially cuboidal configuration.

[0009] The dressing apparatus therefore includes at least two dressing regions, wherein one of the two dressing regions of optimized for the process of restoring the grinding profile and the other of the two dressing regions is optimised for the process of sharpening. Depending on which specific process is implemented the corresponding dressing region is specifically used. It has been found in tests that the service life of the grinding tool dressed with such a dressing apparatus can be almost doubled in comparison with a dressing apparatus in which a compromise is made in the design thereof as between the restoration process and the sharpening process.

[0010] An advantage in that respect is also the fact that the two dressing regions are connected together. Alternatively it would also be possible to consider using two different dressing apparatuses each having a respective dressing region, wherein one of the two dressing apparatuses is designed for the process of restoring the grinding profile and the other of the two dressing apparatuses is designed for the sharpening process. It will be noted however that the two dressing apparatuses would then have to be used alternately, which involves an increased level of complication and involvement in positioning. In comparison therewith, it is possible with the present dressing apparatus for it to be positioned only once, for example in a feed device, and for firstly the second and then the first dressing region to be used up at least for the predominant part thereof. In that way there is automatically a change between the process of restoring the grinding profile and the sharpening process, without the position of the dressing apparatus relative to the feed device having to be changed.

[0011] In that respect it has proven to be particularly desirable in relation to handling of the dressing apparatus for the dressing apparatus to have a longitudinal axis and for the two dressing regions to be arranged in succession in the direction of the longitudinal axis.

[0012] Furthermore, in relation to handling the dressing apparatus it has proven to be advantageous that the dressing apparatus is of a substantially cuboidal configuration, preferably of a length of 150 mm to 250 mm, particularly preferably 180 mm to 200 mm, and/or a width of 25 mm to 75 mm, particularly preferably about 50 mm, and/or a thickness of 2.0 mm to 10.0 mm, particularly preferably about 3.0 mm, 4.0 mm or 5.5 mm.

[0013] And finally, in relation to handling the dressing apparatus, it is also advantageous that the dressing apparatus has a holding region for holding the dressing apparatus when dressing the grinding tool, wherein preferably the holding region is of an abrasive grain-less nature and/or is secured by adhesive or sintering, and/or substantially comprises a water-soluble material. Without that holding region the dressing apparatus would have to be held at one of the two dressing regions which, in the region used for holding purposes, could no longer be used for dressing and would have to be disposed of as waste.

[0014] In principle the holding region can already be manufactured in manufacture of the two dressing regions. Then a material is used, which withstands pressure and temperature in manufacture of the dressing regions. Here for example an inexpensive ceramic material presents itself as an option, similarly to a "low-cost core" in the case of ceramic grinding discs.

[0015] Alternatively it is possible to fit the holding region only after manufacture of the two dressing regions, for example using adhesive. In that case it is possible to use the most widely varying materials like for example wood, plastic or organic materials. A prerequisite is sufficient strength and the possibility of securing it to the dressing regions by adhesive.

[0016] In the situation where the material of the holding region is water-soluble it would be possible to easily dispose of or recycle the holding region after use thereof, by dissolving in water.

[0017] Because the first dressing region is of a larger volume than the second dressing region it is possible to set an optimum relationship between the dressing step of profiling and the dressing step of sharpening. More specifically in practice the situation is frequently such that a grinding tool is profiled at a lesser degree of frequency than it is sharpened, and that a smaller volume of dressing material is consumed in the profiling operation in comparison with the shaping operation.

[0018] In that respect it has been found to be advantageous for the volume of the first dressing region to be about 4 to 7 times, preferably about 6 times, greater than the volume of the second dressing region.

[0019] The specification of the first and second dressing regions depends on the specific configuration of the grinding tool and the specific use of the grinding tool. In general the specification of the second grinding region will be selected to be more aggressive than the specification of the first dressing region, whereby the specification of the second dressing region is adapted to remove more abrasive grain and/or binder material, in comparison with the specification of the first dressing region.

[0020] For example, for dressing grinding tools which are used for grinding workpieces in the form of glass panes it is appropriate for the first specification to be of a mean pore size of 200 to 500 .mu.m, preferably about 350 .mu.m, and/or to have white corundum as the abrasive, and/or to have an abrasive grain with a grain size of 120 to 220 mesh, preferably about 180 mesh.

[0021] In regard to the second specification it is advantageous for the second specification to be of a porosity in the range of 10 to 15 percent by volume and/or to have a mixture of white corundum and pink corundum and/or red corundum as the abrasive grain, and/or to have an abrasive grain of a grain size of 35 to 100 mesh, preferably about 55 mesh.

[0022] White corundum comprises up to over 99.9% Al.sub.2O.sub.3 (aluminium oxide) and has a high level of hardness and heat resistance up to 2000.degree. C. Pink corundum has low proportions of foreign substances which impart a somewhat higher grain toughness thereto and permit the use thereof for shaping and profile grinding by virtue of a higher degree of edge strength. Otherwise it corresponds to white corundum. The foreign substances added are for example chromium or titanium as oxide in the melting process. For the situation where chromium oxide is added as the foreign substance it is possible to distinguish pink corundum and red corundum from each other by virtue of the fact that pink corundum contains approximately 0.25% Cr.sub.2O.sub.3 while red corundum contains about 2% Cr.sub.2O.sub.3.

[0023] A ceramic binder is suitable as the binding agent both in the case of the first and also in the case of the second specification.

[0024] As stated in the opening part of this specification protection is also claimed for a method of dressing a grinding tool by means of at least one dressing apparatus according to the invention, wherein the method includes a first method step in which the grinding profile of the grinding tool is restored by means of the second dressing region of the at least one dressing apparatus and a second method step in which the grinding profile of the grinding tool is sharpened by means of the first dressing region of the at least one dressing apparatus.

[0025] Preferably the first method step takes place before the second method step. The two method steps however could also be carried out in the reverse sequence in time.

[0026] In addition it is desirable for the first method step to be repeated at a first frequency N1 before the second method step is carried out and for the second method step to be repeated at a second frequency N2 after conclusion of the first method step which is repeated at the frequency N1, wherein N1<N2.

[0027] It has also proven to be advantageous that, before the second method step, the first method step is carried out or repeated until at least a predominant part of the second dressing region is consumed and after conclusion of the first method step the second method step is carried out or repeated until at least a predominant part of the first dressing region is consumed. In that way an automatic change can be implemented between the profiling dressing step and the sharpening dressing step.

[0028] Further advantageous embodiments of the method provide that: [0029] before the first method step and/or between the first and second method steps and/or after the second method step and/or between the possibly provided repetition of the first or second method step the grinding tool is used a plurality of times for grinding at least one workpiece, preferably a glass pane, and/or [0030] the dressing apparatus has a holding region for holding the dressing apparatus when dressing the grinding tool and the at least one dressing apparatus is held at least during the first and second method steps at least at the holding region in a feed device, and/or [0031] the method is carried out sequentially with a plurality of successive dressing apparatuses, wherein a further dressing apparatus is fed, preferably from a magazine, as soon as a preceding dressing apparatus is consumed at least for the predominant part, and/or [0032] the method takes place in automated fashion at least for its predominant part.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Further details and advantages of the invention are described more fully hereinafter by means of the specific description with reference to the drawings in which:

[0034] FIG. 1a is a diagrammatic perspective view of an arrangement comprising a workpiece, a grinding tool and a dressing apparatus,

[0035] FIG. 1b is a diagrammatic side view of a grinding operation on a workpiece, wherein the illustrated dressing apparatus is out of engagement,

[0036] FIG. 1c is a diagrammatic side view of an arrangement comprising a workpiece and a grinding tool before the beginning of a grinding operation,

[0037] FIG. 1d is a diagrammatic side view of an arrangement comprising a workpiece and a grinding tool during a grinding operation,

[0038] FIG. 2a is a diagrammatic perspective view of a first preferred embodiment of a dressing apparatus,

[0039] FIG. 2b is a diagrammatic perspective view of a second preferred embodiment of a dressing apparatus,

[0040] FIG. 3 is a diagrammatic perspective view of an arrangement comprising a grinding tool and two dressing apparatuses in a first embodiment,

[0041] FIG. 4a is a diagrammatic side view of an arrangement comprising a grinding tool and a plurality of dressing apparatuses in a second embodiment,

[0042] FIG. 4b is a diagrammatic side view of an arrangement comprising a grinding tool and a plurality of dressing apparatuses in a third embodiment,

[0043] FIG. 4c is a diagrammatic side view of an arrangement comprising a grinding tool and a plurality of dressing apparatuses in a fourth embodiment,

[0044] FIG. 5 is a diagrammatic enlarged view of a part of a dressing apparatus,

[0045] FIG. 6a is a diagrammatic side view of the dressing step of profiling a grinding tool by means of a dressing apparatus,

[0046] FIG. 6b is a diagrammatic side view of the dressing step of sharpening a grinding tool by means of a dressing apparatus, and

[0047] FIG. 7 is a diagrammatic view illustrating a method of dressing a grinding tool which is used for processing a workpiece, by means of at least one dressing apparatus.

DETAILED DESCRIPTION OF THE INVENTION

[0048] FIG. 1a shows a grinding tool 2 mounted rotatably about an axis of rotation 33. The grinding tool 2 has a groove-shaped grinding profile 14, with which the edge 51 of a workpiece 15 in the form of a glass pane can be ground. It will be appreciated that the invention is not limited to dressing a grinding profile of a groove-shaped configuration of a grinding tool.

[0049] The workpiece 15 is mounted displaceably and rotatable in all directions 52 in space. In addition there is provided a feed device 16 in which a dressing apparatus 1 is mounted. The dressing apparatus 1 is held in the feed device 16 in positively locking relationship. In addition there is provided a hold-down clamp 30 for holding the dressing apparatus 1.

[0050] As FIG. 1b shows the workpiece 15 can be arranged for example by way of holding devices 31 on a carrier 32, wherein the holding devices 31 and/or the carrier 32 can be displaceable in the directions 52 in space.

[0051] As FIG. 1b further shows the grinding tool 2 can be clamped in a clamping device 28 of a grinding machine 26.

[0052] The sequence of FIGS. 1c and 1d diagrammatically shows the operation of grinding the edge 51 of the workpiece 15 by means of the grinding tool 2. In the position shown in FIG. 1c the edge 51 of the workpiece 15 is spaced from the grinding profile 14 of the grinding tool 2. In the position shown in FIG. 1d the grinding profile 14 of the grinding tool 2 is in engagement with the edge 51 of the workpiece 15. In that case material of the workpiece 15 is removed by a relative movement of the grinding profile 14 and the abrasive grains 13 therein relative to the workpiece 15.

[0053] In accordance with a first preferred embodiment shown in FIG. 2a the dressing apparatus 1 has a first dressing region 3 and a second dressing region 4 connected thereto, wherein the first dressing region 3 has a first specification for sharpening the grinding profile 14 of the grinding tool 2 and the second dressing region 4 has a second specification, differing from the first specification, for restoring the grinding profile 14 of the grinding tool 2, and wherein the first dressing region 3 is of a larger volume than the second dressing region 4.

[0054] The dressing apparatus 1 is of a substantially cuboidal configuration, wherein the length of the dressing apparatus 1 is denoted by reference 6, the width is denoted by reference 7 and the thickness by reference 8.

[0055] The dressing apparatus 1 has a longitudinal axis 5. The two dressing regions 3 and 4 are arranged in succession in the direction of the longitudinal axis 5.

[0056] In accordance with a second preferred embodiment shown in FIG. 2b the dressing apparatus 1, in comparison with the first preferred embodiment, has an additional holding region 9 for holding the dressing apparatus 1 when dressing the grinding tool 2 wherein the holding region 9 is of an abrasive grain-less nature.

[0057] Naturally the dressing apparatus 1 in accordance with the first preferred embodiment can also be held in the dressing operation, more specifically for example at the dressing region 3, as can be seen inter alia from FIG. 3.

[0058] In the embodiment shown in FIG. 3 the feed device 16 has a magazine 17 for two dressing apparatuses 1 which are arranged in the magazine 17 in succession in the direction of the longitudinal axis of the dressing apparatuses 1. One of the dressing apparatuses 1 projects by a distance from the feed device 16. That dressing apparatus 1 is now used firstly for dressing the grinding tool 2, more specifically until the dressing apparatus 1 is used up to such an extent that it can no longer be held in the feed device 16. Thereafter the dressing apparatus 1 arranged therebehind is used for dressing the grinding tool 2. The empty location which thereby occurs in the magazine 1 can be filled up by a further dressing apparatus 1.

[0059] In the embodiment shown in FIG. 4a the feed device 16 includes a magazine 17 which, in comparison with the magazine shown in FIG. 3, has on the one hand a loading device 27 for re-loading the dressing apparatuses 1 as well as an actuator 25 for the forward feed of the dressing apparatuses 1 in the direction of the grinding tool 2 to be dressed. In the illustrated situation dressing apparatuses 1 according to the second preferred embodiment are disposed in the magazine 17. Alternatively or supplementally dressing apparatuses 1 according to the first preferred embodiment can also be arranged in the magazine 17.

[0060] In addition there is provided a catch device 29 in which residues, which have not been used, of the dressing apparatuses 1 can be collected. If this involves dressing apparatuses 1 according to the second preferred embodiment the residues substantially consist of the holding regions 9 of the dressing apparatuses 1. If dressing apparatuses 1 according to the first preferred embodiment are involved then the residues substantially consist of pieces of the dressing regions 3 and/or 4.

[0061] FIG. 4b shows an embodiment in which the feed device 16 is displaceable in the direction of the grinding tool 2 or in the reverse direction by way of a manual feed means 18, for example in the form of a spindle drive.

[0062] FIG. 4c shows an embodiment in which the dressing apparatuses 1 can be conveyed into an active dressing position from the magazine 17 fully automatically by means of an actuator 25 which is actuated by an automatic delivery device. In addition there is provided a detection device 24 with which the state of dressing apparatuses 1 in the magazine 17 can be detected. Finally there is provided an open-loop and/or closed-loop control device 20 which communicates at least with the detection device 24 and the automatic delivery device 19.

[0063] FIG. 5 shows a diagrammatic enlarged view of a part of a dressing apparatus 1. The dressing region 4 includes a specification for restoring the grinding profile of a grinding tool, wherein that specification involves a porosity in the range of 10 to 15 percent by volume and a mixture of white corundum and pink corundum and/or red corundum as abrasive grain of a grain size of about 55 mesh. The dressing region 3 includes a specification for sharpening the grinding profile of a grinding tool, wherein that specification involves a mean pore size of about 350 .mu.m and white corundum as the abrasive grain of a grain size of about 180 mesh.

[0064] FIG. 6a diagrammatically shows the dressing step of profiling a grinding tool 2 with a dressing apparatus 1, in which case the grinding tool 2 comes into contact with the dressing region 4. In that situation the dressing region 4 is used up until the grinding tool 2 comes into contact with the dressing region 3 (see FIG. 6b) and the sharpening dressing step automatically takes place. It is appropriate for the method step of restoring the grinding profile of a grinding tool to be repeated at a frequency N1 and for the sharpening method step to be repeated at a frequency N2, wherein N1<N2.

[0065] The change from restoring the grinding profile to sharpening is also shown once again diagrammatically in the upper part of FIG. 7. The lower part of FIG. 7 shows the option whereby the grinding tool 2 can be used a plurality of times for grinding at least one workpiece 15, preferably a glass pane, prior to the first method step 11 and/or between the first and second method steps 11 and 12 and/or after the second method step 12 and/or between an optionally provided repetition of the first or second method steps 11 and 12.

Claims

1. A dressing apparatus for dressing a grinding tool provided with a predetermined grinding profile, wherein the dressing apparatus includes at least a first dressing region and a second dressing region connected thereto, wherein the first dressing region has a first specification for sharpening the grinding profile of the grinding tool and the second dressing region has a second specification differing from the first specification for restoring the grinding profile of the grinding tool, the first dressing region is of a larger volume than the second dressing region, the dressing apparatus has a longitudinal axis, the two dressing region are arranged in succession in the direction of the longitudinal axis and the dressing apparatus is of a substantially cuboidal configuration.

2. The dressing apparatus according to claim 1, wherein the volume of the first dressing region is about 4 to 7 times, preferably about 6 times, greater than the volume of the second dressing region.

3. The dressing apparatus according to claim 1, wherein the dressing apparatus has: a length of 150 mm to 250 mm, particularly preferably 180 mm to 200 mm, and/or a width of 25 mm to 75 mm, particularly preferably about 50 mm, and/or a thickness of 2.0 mm to 10.0 mm, particularly preferably about 3.0 mm, 4.0 mm or 5.5 mm.

4. The dressing apparatus according to claim 1, wherein the first specification: has a mean pore size of 200 to 500 .mu.m, preferably about 350 .mu.m, and/or has white corundum as the abrasive grain, and/or has an abrasive grain of a grain size of 120 to 220 mesh, preferably about 180 mesh.

5. The dressing apparatus according to claim 1, wherein the second specification: has a porosity in the range of 10 to 15 percent by volume, and/or has a mixture of white corundum and pink corundum and/or red corundum as the abrasive grain, and/or has an abrasive grain with a grain size of 35 to 100 mesh, preferably about 55 mesh.

6. The dressing apparatus according to claim 1, wherein the dressing apparatus has a holding region for holding the dressing apparatus when dressing the grinding tool, preferably wherein: the holding region is of an abrasive grain-less nature and/or is secured by adhesive or sintering, and/or substantially comprises a water-soluble material.

7. A method of dressing a grinding tool by the dressing apparatus according to claim 1, including a first method step in which the grinding profile of the grinding tool is restored by means of the second dressing region of the at least one dressing apparatus, and a second method step in which the grinding profile of the grinding tool is sharpened by means of the first dressing region of the at least one dressing apparatus.

8. The method according to claim 7, wherein the first method step is repeated at a first frequency before the second method step is carried out and the second method step is repeated at a second frequency after conclusion of the first method step which is repeated at the frequency N1, wherein N1<N2.

9. The method according to claim 7, wherein, before the second method step is carried out the first method step is carried out or repeated until at least a predominant part of the second dressing region is used up and after conclusion of the first method step the second method step is carried out or repeated until at least a predominant part of the first dressing region is used up.

10. The method according to claim 7, wherein the grinding tool is used a plurality of times for grinding at least one workpiece, preferably a glass pane, before the first method step and/or between the first and second method steps and/or after the second method step and/or between an optionally provided repetition of the first or second method step.

11. The method according to claim 7, wherein the dressing apparatus has a holding region for holding the dressing apparatus when dressing the grinding tool and the at least one dressing apparatus is held at least at the holding region in a feed device at least during the first and second method steps.

12. The method according to claim 7, wherein the method is carried out sequentially with a plurality of successive dressing apparatuses, wherein a further dressing apparatus, is fed preferably from a magazine as soon as a preceding dressing apparatus is used up at least for the predominant part.

13. The method according to claim 7, wherein the method takes place in fully automated mode at least for the predominant part.

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