Device for fine grinding and polishing of hard materials

Abstract

 Device for fine grinding and polishing stone and other hard materials, e.g. granite or marbles in the form of blocks, plates or sheets. The device is designed to be used with a machine including at least two arms performing a combination of a rotative and oscillating movement along a surface to be treated. Each arm of said machine comprise an attachment arrangement for a curved grinding block to perform a grinding (by use of a self cleansing contact), defining a translating one-dimensional line contact (at 20) along a surface to be treated. The attachment arrangement (1) comprises at least two parts (2, 3), joined to each other by means of a shaft (4) parallel to said translating contact line at (20), a first part (2) thereof being attached (at 7) to an arm and a second part (3) thereof having a second attachment at (8) for a fine grinding or polishing block (14) with a flat working surface, so that when said block is applied against a surface to be treated, a two-dimensional surface contact will occur.

Description

[0001] The present invention relates to a device for fine grinding and polishing stone and other hard materials, e.g. granite or marbles in the form of blocks, plates or sheets, by means of a machine including at least two arms performing a combination of a rotative and oscillating movement along a surface to be treated and each arm comprising an attachment arrangement for a curved grinding block to perform a grinding (by use of a self cleansing contact) defining a translating one-dimensional line contact along a surface to be treated.

[0002] Materials such as granite are frequently used as floorings and as coverings on building frontages when it is desired to create an impressive surface or façade. Such a surface is, when finally mounted, supposed to be both decorative and maintainence free. It is therefore essential that the elements of for instance granite is so ground and polished that they both individually and mounted together create a planar surface.

[0003] Fine grinding and polishing blocks or floors of for instance granite or marble are today normally made manually, ie. a wooden plate having a grinding surface is pushed back and forth on the surface to be treated, the material of the grinding surface being gradualy consecutively changed to a finer one. During the final stage felt can be used as polishing material.

[0004] Manual grinding and polishing is of course both inefficient and expensive. Attempts to use machines for the purpose have hitherto been less successful. An exemple of such a machine is shown in US-A-4 965 965. These attempts have, however, less successful in that they have led to the formation of wave-like surfaces, creating an undesirable surface when mounted. Such surfaces may also, if used for instance as flooring, enhance the risk for people stumbling thereon. Such wave-like surfaces may also represent a hazard when used as façade-coverings due to the creation of undesirable reflections of the sun.

[0005] Thus the original manual method using wooden blocks covered with grinding or polishing materials is still being used, but is inefficient.

[0006] The object of the present invention is therefore to provide means for making it possible to use machines instead of being forced to use manually grind and polish, whereby a higher efficiency is obtained.

[0007] Another purpose of the invention is to achieve a total industrial concept when manufacturing for instance plates of granite or the like for covering floors or façades.

[0008] It is also a purpose of the invention to reach a device which is easy to handle and which even might make it possible to take advantage of previously made investments in grinding heads using oscillating grinding blocks.

[0009] According to the invention the attachment arrangement comprises at least two parts, joined to each other by means of a shaft parallel to said translating line, a first part thereof being attached to an arm and a second part thereof having a second attachment for a fine grinding or polishing block with a flat working surface, so that when said block is applied against the surface to be treated, a two-dimensional surface contact will occur.

[0010] By such an arrangement the great advantage is obtained that a coarse grinding machine, e.g. like the one described in US-A-4 965 965, aimed to be used with a self-cleansing line contact during grinding, easily can be transformed into a fine grinding or polishing machine using a two-dimensional surface contact to perform its duty as a fine grinding or polishing machine as well.

[0011] According to another aspect of the present invention the first part thereof is attached to each arm using a self-locking dove-tail arrangement. Thereby the engagement between the parts becomes tighter and tighter the higher the rotational speed of the machine becomes. Thus the risk that the arrangement according to the invention loosens from the machine is eliminated.

[0012] According to yet another aspect of the present invention the first and second parts of the arrangement comprise differently configurated dovetails thus elimination the risk that they are inadvertently mixed up.

[0013] In the following the invention will be described more in detail with reference to the enclosed drawings, illustrating an embodiment thereof and in which:

FIG 1 is a schematic perspective view of the arrangement according to the invention,

FIG 2 is an end view of said arrangement,

FIG 3 is a top view of the same arrangement, however partly cut along the line III-III in FIG 2,

FIG 4 is a cross-section along the line IV-IV in FIG 3, and

FIG 5 is a partially sectioned side view along the long side of the arrangement according to the invention.

[0014] The cross sectioned parts of FIG 3 and FIG 5 correspond to each other with the cross section arrows III'-III' and V'-V' respectively.

[0015] The arrangement according to the invention aims at achieving an elimination of the otherwise occurring oscillating movement of grinding elements, which are normally partially circular. Such an oscillating fine grinding or polishing movement will generate a wave-like surface which may not be directly visible for the bare eye. The effect may, however, be visible under certain light conditions. For other consequences of such a wave-like surface, reference is made to the previous description.

[0016] It has been found that in order to avoid such wave formations, the movement during such fine grinding or polishing has to be as planar as possible. To achieve this and at the same time get a highly efficient treatment it is according to the present invention suggested to make use of an arrangement that by a counter-action eliminates this positively achieved oscillating movement by using forces normally acting between the elements taking part in a machine grinding procedure. This is in this case achieved in that when a planar grinding block is positively held against and moved along a surface to be fine ground or polished, the oscillating movement is taken up in an intermediate portion pivotable between two outer extreme positions beyond the reach of the normal oscillation, relating to the actual oscillating angles of a grinding arm.

[0017] In FIG 1 a schematic perspective view of the arrangement 1 according to the invention is shown to establish a better foundation for understanding the invention.

[0018] The arrangement 1 comprises a first part 2 to be connected to a grinding machine (not shown) for performing an oscillating and rotative movement along a surface to be treated, the oscillating part of which is to be eliminated in order to create a surface contact instead of a line contact, as described above. The arrangement 1 also comprises a second part 3, joined to the first part 2 using a shaft 4, penetrating both parts 2,3. Said second part 3 has a dovetail arrangement 8 for the attachment of a grinding or polishing segment 14, which is to maintain a surface contact with the surface to be polished. The first part 2 is pivotally journalled on the shaft 4. The parts 2, 3 are prestressed in relation to each other by means of using springs 13, into a position corresponding to that shown in FIG 1. The reason is that the second part 3 needs to have a proper starting position during commencement of its application to a surface to be treated. Also the first part has a dovetail arrangement for its attachment to an arm of the machine. This is designated 7 since it has a different configuration than the arrangement 8 in order to avoid the risk of mixing them up.

[0019] Fig 2 is an end view of the arrangement. Here the arrangement of the springs 13 is more clearly shown (even more clearly in FIG 3), as well as the different configurations of the dove-tail arrangements 7, 8. As a hidden contour also a channel 15 and a screw 16 are shown. This will, however, be more detailed with reference to FIG 4 below.

[0020] In FIG 3 a partial view from above as well as a partial cross section/view along the line III-III in Fig 2 is shown. The above mentioned screw 16 is here shown to be flush with the upper surface 17 of the first part 2. The reason is that it has to fit in to a correspondingly flat surface of a corresponding dove-tail of the grinding machine (not shown). In the cross-section portion of FIG 3 the shaft 4 and its fitting 11 (in general) is visible. A spring 12, normally covered by said screw 16, puts a load from the first part 2 onto a flat surface of the shaft 4, thus keeping the journalling surface of the shaft in a sliding contact (using a bushing 10 made of eg GLYKODUR®) with an oblong corresponding journalling hole 19 (see FIG 4), the oblongness of which is about A=3mm. The hole 19 must have this configuration since during the fine grinding or polishing movement a center point of the machine attachment corresponding to a point designated as 20, describes a vertical movement of approximately this height. Thus the pivot between the second part 3 and the shaft 4 takes place in an outer bushing 21, being lubricated in any suitable way.

[0021] Finally Fig 5, being a partially sectioned side view of the arrangement 1 and being cross connected to FIG 3 as described above, shows the interrelationship between the different parts described above. This illustration especially shows how the 3mm gap (resulting from the oblongness of the hole 19), that exists between the oblong hole 19 in the second part and the bushing 10 is arranged when the arrangement according to the invention is in a relieved condition. Said gap will during use be almost fully used to take up the vertical movement described above.

Claims

1. Device for fine grinding and polishing stone and other hard materials, e.g. granite or marbles in the form of blocks, plates or sheets, by means of a machine including at least two arms performing a combination of a rotative and oscillating movement along a surface to be treated and each arm comprising an attachment arrangement for a curved grinding block to perform a grinding (by use of a self cleansing contact), defining a translating one-dimensional line contact (at 20) along a surface to be treated, characterized in that the attachment arrangement (1) comprises at least two parts (2, 3), joined to each other by means of a shaft (4) parallel to said translating line (20), a first part (2) thereof being attached (at 7) to an arm and a second part (3) thereof having a second attachment (8) for a fine grinding or polishing block (14), with a flat working surface so that when said block is applied against a surface to be treated, a two-dimensional surface contact will occur.

2. Arrangement according to claim 1, characterized in that the first part (2) is attached to the arm using a first self-locking dovetail arrangement (7).

3. Arrangement according to claim 2, characterized in that the second part (3) has a second dovetail arrangement (8) with another configuration than the first one.

4. Arrangement according to anyone of the preceding claims, characterized in that one of the first and second parts (2, 3) is pivotally and translatably arranged in relation to the other.

5. Arrangement according to claim 4, characterized in that the first and second parts (2, 3) are journalled in bushings (10) relative to each other.

6. Arrangement according to claim 5, characterized in that said bushings (10) are manufactured from GLYKODUR®.

7. Arrangement according to claim 6, characterized in that the fitting (11) of one of said bushings (10) is oblong.

8. Arrangement according to claim 7, characterized in that said one bushing (10) is semicircular.

9. Arrangement according to claim 8, characterized by springs (12) for biasing prestressing the shaft (4) against the bushings.

10. Arrangement according to claim 9, characterized in that said first and second parts (2, 3) in a stationary condition are held in a certain position by means of springs (13) at each side of the shaft (4) and between the parts (2, 3).

Drawing