EP2228694A1 - Method and device for grinding watch glasses - Google Patents

Abstract

The method involves providing watch glasses (22) to be ground on a cylindrical outer surface (20) or an inner surface of a rotating drum (18). The watch glasses are pressurized by a grinding disk (16). A set of curvatures is created in the watch glasses, where the curvatures are provided with curvature radii and run right-angle to each other. An effective grinding surface of the grinding disk is provided with another set of curvatures, which is complementary to one of the former set of curvatures, where the grinding surface is concavely or convexly cambered. An independent claim is also included for a device for grinding watch glasses.

Description

The invention relates to a method for grinding watch glasses, in particular those made of sapphire, in which the watch glasses a first curvature with a first radius of curvature and a perpendicular extending second curvature is sanded with a second radius of curvature, with several to be ground watch glasses on the circumference of a rotatable Drum are arranged and acted upon by at least one rotatable grinding wheel. The watch glasses to which the invention relates are in their simplest form one-sided, i. just on the top, cambered. Furthermore, the present invention relates to an apparatus for carrying out the inventive method.

State of the art

Such glasses serve as coverslips and give the watches a special aesthetic touch.

For example, the patent document describes EP-B1-0948758 a rectangular in plan view clock glass whose lower surface is flat and the upper surface is crowned in the manner of a Torussegments. This means that the upper surface of the watch glass has two different radii of its convex curvature, wherein the larger radius of curvature, ie the lower curvature, corresponds to the longitudinal axis of the rectangle. This particular design of the watch glass results in a watch glass that is thicker in the center than at the edge and has a more uniform thickness at the edge than other watch glasses that have a cylindrical or spherical curvature of the top surface.

From the document EP-B1-1645919 is a method for mechanical multi-part processing of watch glasses. This method provides a watch glass, the bottom and top are each cambered so that the wall thickness of the glass is substantially the same and constant everywhere. In the process, approximately rectangular or oval starting glasses are ground first on the top in the longitudinal direction and then in the transverse direction, whereby a convex top is formed, and then ground again on its underside with slightly smaller radii of curvature and in the same two-stage manner. For grinding, the glasses are attached to a rotatable disc or to a rotatable drum.

This process requires four steps in terms of grinding and still further process steps to secure the jars and adjust the grinding radii. Therefore, the process is delicate and very expensive.

In the already mentioned patent document EP-B1-0948758 discloses a method for producing the described watch glass, which is carried out by means of a device which consists essentially of a drum rotatably driven about a first axis and arranged in extension of the drum and rotationally driven about a second axis grinding body. The grinding wheel is located on a carriage, which is pivotable about a third axis perpendicular to the first axis.

The drum is provided for receiving the watch glasses to be ground, for example with the long side in the circumferential direction of the drum, and flattened at the attachment points of the glasses. When grinding, the drum rotates with the glasses in front of a rotating grinding wheel and the glasses get their curvature in accordance with the drum radius (and additionally the glass thickness).

But the grinding wheel can also exert a lateral pivoting movement to both sides of the glasses and thereby generates the curvature of the narrow sides of the rectangular glass.

This process is time consuming because the glasses on the drum must rotate very long in front of the grinding wheel to produce the lateral curvature of the glasses, because the working surface between glass and grinding tool is very small, almost linear. In addition, it is necessary to tune the lateral movements of the grinding wheel exactly to the rotation of the drum in order to obtain a constant curvature to the sides. Finally, the method of this patent document is limited to the grinding of elongated watch glasses, for example rectangular or oval glasses.

Description of the invention

The invention has for its object to provide a substantially improved and simplified method that can be carried out by simple means and supplies exactly ground glasses in less time and at a lower cost.

This object is achieved by the method according to the invention, which is defined in the first independent claim. The inventive device is characterized in the second independent claim. Particular or preferred embodiments form the subject of the dependent claims.

According to the invention, the two different curvatures of the glasses are produced simultaneously, wherein there is a flat contact between the grinding tool and the glasses moving in front of it or is generated in a short time after the beginning of the grinding process. This procedure contributes significantly to the faster execution of the method.

The simultaneous machining in two directions, which are substantially perpendicular to each other, results in a continuous transition between the two different radii of curvature of the curvature, which are also substantially perpendicular to each other. It will open this way creates a particularly appealing appearance of the watch glass.

In a particular embodiment of the invention, an acute angle can be provided between the axes of the two active elements, namely, the glass occupied with the disc and the grinding wheel. This results in domed watch glasses whose lateral edges have different thicknesses.

The inventive method is not limited to elongated glasses; It can be ground with the same success and round glasses. It may be advisable to mark the direction of the curvature beforehand on the glass. In the method according to the invention, watch glasses made of any materials can be processed, for example glass, hard materials such as sapphire, rock crystal and other transparent semi-precious stones, plastics such as Plexiglas® and other transparent materials. It is of course to choose the appropriate abrasive, which is natural for the expert.

The term "grinding" as used in this document also includes the polishing of the processed glasses.

The inventive method allows a fast grinding of the watch glasses using a particularly simple device. Even if it is desired to grind with serially different radii of curvature, this condition can be met by rapid replacement of the drum and / or grinding wheel. Finally, it is still possible to easily produce asymmetric crowns by shaping the peripheral surface of the grinding wheel accordingly.

According to a further development of the device according to the invention, it is possible to practically double the already high processing speed. This is achieved by simultaneously acting two grinding wheels on the right angles to rotating watch glasses.

embodiments

The invention will now be explained further with reference to the drawing of exemplary embodiments; these examples are pure information and in no way limit the invention.

In the drawing, all the device elements are shown only schematically, and it is clear to the person skilled in the art that the necessary (and not according to the invention) additional devices are yet to be supplemented, e.g. Controls of drives, adjusting devices, devices for the supply, removal and processing of grinding, cooling and polishing materials as powders or liquids, tanks, pipelines, cooling or heating devices, etc.

In addition, only round watch glasses are shown for grinding in the figures. It should again be emphasized that even non-round glasses can be ground.

Brief description of the drawing

• Fig. 1 eine perspektivische Ansicht einer ersten Schleifvorrichtung für das erfindungsgemässe Verfahren zur Herstellung konvex geschliffener Gläser;
• Fig. 2 eine teilgeschnittene Draufsicht der Vorrichtung gemäss Fig. 1 in Richtung des Pfeils D;
• Fig. 3 eine perspektivische Ansicht einer zweiten Schleifvorrichtung für das erfindungsgemässe Verfahren zur Herstellung konkav geschliffener Gläser;
• Fig. 4 eine teilgeschnittene Draufsicht der Vorrichtung gemäss Fig. 3 in Richtung des Pfeils D;
• Fig. 5 eine perspektivische Ansicht einer dritten Schleifvorrichtung für das erfindungsgemässe Verfahren zur Herstellung konvex oder konkav geschliffener Gläser, in Ruhestellung;
• Fig. 6 eine Ansicht der Vorrichtung wie in Fig. 5, aber in Arbeitsteilung; und
• Fig. 7 einen Querschnitt der Vorrichtung gemäss Fig. 6 in der durch die Linie und die Pfeile VII-VII angezeigten Ebene.

In the drawing:

• Fig. 1 a perspective view of a first grinding device for the inventive method for producing convex ground glasses;
• Fig. 2 a partially sectioned plan view of the device according to Fig. 1 in the direction of arrow D;
• Fig. 3 a perspective view of a second grinding device for the inventive method for producing concave ground glasses;
• Fig. 4 a partially sectioned plan view of the device according to Fig. 3 in the direction of arrow D;
• Fig. 5 a perspective view of a third grinding device for the inventive method for producing convex or concave ground glasses, in the rest position;
• Fig. 6 a view of the device as in Fig. 5 but in division of labor; and
• Fig. 7 a cross section of the device according to Fig. 6 in the plane indicated by the line and the arrows VII-VII.

Detailed description of the embodiments of the invention

It will be referred to first Fig. 1 taken, wherein a first embodiment of the inventive device is shown in perspective. On a base 10, a motor 12 is mounted on the axis 14, a grinding wheel 16 is attached. Axially parallel to the axis 14, a drum 18 is rotatably arranged, which has the shape of a cylindrical disc, on the peripheral surface 20, a number of watch glasses 22 are glued. The glasses 22 are drawn here round; but it can also be provided glasses of another shape, for example, oval or rectangular or square. The drive mechanism of the drum 18 is not shown in the drawing (this applies to all figures).

Since the motor 12 rests on the base 10 via a displaceable base plate 24, it can be approximated to the glasses 22 in the direction of the arrow V and be removed in the opposite direction.

The configuration of the grinding wheel 16 is better Fig. 2 out. The pressed abrasive grains 30 forming the abrasive article are enclosed between the cover plates 28. The abrasive body extends circumferentially beyond the shrouds 28, and the peripheral surface 26 is not flat, as in the known grinding wheels, but it is concavely curved, wherein the radius of curvature is denoted by R1.

On the outer circumferential surface of the drum 18 are the individual glasses to be ground 22. Their distance from the central axis A of the drum 18 is denoted by R2. In operation, the drum 18 is rotated, and the grinding wheel 16 is also rotated and approached to the drum 18 in the direction of arrow V.

After completion of the grinding work, the grinding wheel 16 and the drum 18 are stopped. After removing the watch glasses 22 from the drum 18, they have a first curvature with the radius R1 and a second curvature with the radius R2, wherein the planes of the two curvature circles are perpendicular to each other. If R1 = R2, then a spherical cut is produced; In the case of inequality of R1 and R2, a toric cut is obtained, whereby the two different curvatures merge into one another steplessly, which produces a particularly appealing aesthetic impression.

The second embodiment of the inventive device is in the Fig. 3 and 4 shown, wherein for elements which are those in the Fig. 1 and 2 correspond, the same reference numerals are used.

The device after Fig. 3 and 4 serves to produce concave ground glasses. For this purpose, the drum 28 is formed as a hollow cylinder, and to be ground glasses 22 are on a cylindrical inner surface 20 '(FIG. Fig. 4 ) of the drum 28, which is located at a distance from R2 to the drum axis A. The outer circumference 26 of the grinding wheel 16, ie of the grinding body 30, is curved convexly with a radius of curvature R1 which corresponds to the desired concave curvature of the glasses 22.

To carry out the method, the grinding wheel 16 and the drum 18 are rotated, and the rotating grinding wheel 16 is approached to the glasses 22 in the direction of the arrow V.

As a result of the above-described interaction of the rotating grinding wheel 16 with the rotating drum 18, a toric concave grinding of the glasses 22 with the two main radii of curvature R1 and R2 is achieved (cf. Fig. 4 ).

A third embodiment of the inventive device is in the Fig. 5 to 7 shown. Fig. 5 shows a perspective view of this device at rest and in Fig. 6 in working position. In Fig. 7 is a longitudinal section in the plane shown by the line VII-VII in FIG Fig. 6 is defined. Also in these figures, the same reference numerals are used for the same or similar elements as in the preceding figures, optionally provided with an apostrophe.

Two motors 12, 12 'are arranged coaxially displaceable on mounting blocks 24, 24' on a carriage 32. For holding and guiding serve two parallel columns 34, 34 ', on which sleeves 36, 36' slide, which are part of the mounting blocks 24 and 24 '. The motors 12, 12 'drive via belt drives 38, 38' grinding wheels 16, 16 ', which are formed in this embodiment as a small cylindrical discs, the end face of which acts as a grinding and convex with a radius of curvature R1 is formed (see Fig. 7 ). The axes of rotation of the drum 18 and the grinding wheels 16, 16 'are perpendicular to each other and are also in the same plane.

The drum 18, to which the individual glasses 22 to be ground are fastened, is as in the second embodiment ( Fig. 3 and 4 ) formed as a hollow cylinder, and when grinding the glasses, a concave toric cut is produced.

As in Fig. 5 is shown, the two grinding groups 12-24-38-16 and 12'-24'-38'-16 'on the columns 34, 34' side by side approximately the center of the drum 18, and there is no sliding contact with the glasses 22 instead. Now, if the two grinding groups 12-24-38-16 and 12'-24'-38'-16 'in the direction of the arrows P, P' are removed from each other, finally results in the Fig. 6 shown arrangement. Here the grinding wheels 16, 16 'are in sliding contact with the glasses 22, and the processing according to the method proceeds. Of course, the motors 12, 12 'on the one hand and the drum 18 on the other hand are in rotation at a rotational speed adapted to the grinding work.

In Fig. 7 is a section in the plane VII-VII of Fig. 6 shown. The concave cut produced by the grinding groups 12-24-38-16 and 12'-24'-38'-16 'on the glasses 22 has the two radii of curvature R1 and R2.

The apparatus of the third embodiment allows double grinding performance at the same rotational speeds of the grinding wheel and the drum on which the glasses are mounted.

In the apparatus shown, concave cuts are formed. When convex cuts are to be made, the device can be easily modified as shown in FIG Fig. 7 indicated by dashed lines. The glasses 40 are attached to the outside of the drum 18, and the two abrasive groups, one of which is schematically indicated 42 and 44, act on both sides of the outside in the direction of the arrows Z, Z 'on the glasses 40 a. Of course, one skilled in the art will readily recognize that in this embodiment it is necessary that R3 ≥ R2.

The third embodiment of the device according to the invention is more complex than the other two embodiments. Because of the high processing speed, it is particularly suitable for polishing the ground glasses. It is advantageous if the carriage 32 is pivotally mounted about a pivot axis which is perpendicular to the grinding wheel axes and the drum axis and extends through the intersection thereof.

The ground watch glasses produced in the method according to the invention using the above-described embodiments of the device have a flat underside. If the underside of the glasses is also to be given a toric finish, the ones ground on one side are in turn fastened to the grinding drum again after they have been removed, and the underside can now be ground.

The method according to the invention and the device used therefor were explained in the above description with reference to exemplary embodiments. However, these examples do not limit the invention; on the contrary fall professional refinements and other, not discussed embodiments with the features set out in the claims readily in the scope of the patent.

Claims (11)

A method of grinding watch glasses, wherein the watch glasses (22) a first curvature with a first radius of curvature (R1) and a perpendicular extending second curvature with a second radius of curvature (R2) is ground, wherein a plurality of watch glasses to be ground (22) on the Are arranged circumference of a rotatable drum (18) and are acted upon by at least one rotatable grinding wheel (16), characterized in that said two curves (R1, R2) are generated simultaneously by a rotating grinding wheel (16; 16 ') is used whose abrasive active surface has a curvature which is complementary to said first curvature of radius R1. A method according to claim 1, characterized in that watch glasses (22) having two mutually perpendicular convex curvatures (R1, R2) are generated by the watch glasses (22) on the circumference (20) of a rotating drum (18) with the radius R2 be fixed and ground with a grinding wheel (16) which rotates parallel to the axis with the drum (18) and whose circumference has a concave recess (26) with the radius of curvature R1. A method according to claim 1, characterized in that watch glasses (22) having two mutually perpendicular concave curvatures (R1, R2) are produced by the watch glasses (22) on the circumference of a cylindrical inner surface (20 ') of a hollow cylinder designed as a rotating drum (18), said cylindrical inner surface (20 ') being at a distance R2 from the drum axis (A) and being ground by a grinding wheel (16) rotating axially parallel to the drum (18) and having a convexly curved circumference Elevation (26) having the radius of curvature R1. Method according to one of the preceding claims, characterized in that sapphire glasses are ground. Apparatus for grinding watch glasses, comprising a rotatable drum (18), to which the watch glasses (22) to be ground can be fastened, and a likewise rotatable grinding wheel (16), characterized in that the grinding wheel is concave or convex at its active surface with a Radius of curvature R1 is cambered. Apparatus according to claim 5, characterized in that the drum (18) and the grinding wheel (16) are arranged axially parallel. Apparatus according to claim 5, characterized in that the axes of rotation of the drum (18) and the grinding wheel (16, 16 ') extend at right angles to each other. Apparatus according to claim 5 and 6, characterized in that the drum (18) has the shape of a disc and the surface of the drum (18) serving for fastening the watch glasses (22) is its cylindrical outer peripheral surface, and in that the grinding wheel (16) has on its outer circumference a concave crowning with the radius of curvature R1. Apparatus according to claims 5 and 6, characterized in that the drum (18) has the shape of a hollow cylinder attached to a disk and the surface of the drum (18) serving to fasten the watch glasses (22) comprises the inner cylindrical peripheral surface (20 ') of the drum Hollow cylinder is that the grinding wheel for applying the inside of the hollow cylinder attached watch glasses (22) is set up and dimensioned from the inside, and that the grinding wheel (16) on its outer circumference has a convex crowning with the radius of curvature R1. Apparatus according to claim 5, 7 and 9, characterized in that two grinding wheels (16, 16 ') are provided which can perform a grinding work diametrically with respect to the drum (18) at the same time and with their drives (12, 38, 12', 38 ') between a rest position and a working position are movable. Apparatus according to claim 10, characterized in that the grinding wheels (16, 16 ') with their drives (12, 38, 12', 38 ') are arranged displaceably together on a column arrangement (32).

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