EP0013404B1 - Process for grinding curved surfaces of non metallic solid rotary bodies, in particular glass bodies, and device for carrying out the process - Google Patents

Description

The invention relates to a method for grinding curved surfaces of non-metallic, solid rotating bodies, in particular glass bodies, with the aid of a tool which is held firmly pressed in an elastically movable manner against the rotated solid body, the tool being partially adapted to the surface to be machined, and the invention also relates to an apparatus for performing this method.

When manufacturing goblet or stemmed glasses, either the stem is pressed onto the blown goblet, or the goblet is inflated onto the pressed goblet base. This results in the complicated shapes coming from a glass press. B. the base plate and the stem of the goblet, which are made with tolerance deviations.

The handle can be manufactured in a two-part or multi-part form. This creates more or less pronounced longitudinal seams during pressing, which are particularly visible on the base plate of the handle. The production by pressing is economical and is therefore particularly suitable for the manufacture of bulk articles. Nevertheless, the aim is to improve their quality. So that the necessary embossed longitudinal seams are at least less visible to the eye, the base plate and sometimes the stem have been given a polygonal cross-section that runs down to the base plate. The parting line of the shape then lies directly on the edge of the polygon. If you want a rotationally symmetrical handle, the parting line can no longer be hidden optically.

Methods for circumventing this disadvantage are already known, in which the goblet is shaped in such a way that the stem ends with a pressed tulip shape. After attaching the stem to the goblet, this tulip is heated to the plastic state and shaped with appropriately designed coal jaws while rotating to the base plate. This method has the disadvantage that it gives the base plate concentric, mostly unsightly stripes.

It would be possible to remove the press seam on the base plate by grinding, which is partly done by hand, after which it is then polished. This method using a rotating grinding wheel is very expensive due to the manual work.

The mechanization of this manual process has so far had to fail for the following reasons: Chalices and stems for goblets are made in the plastic state without cutting by means of blowing or pressing. In contrast to the machining process, such a production naturally has a greater tolerance of several tenths of a millimeter, which is noticeable in terms of the roundness, the coaxiality and the angular offset of the calyx axis and the stem axis. For these reasons, it is not possible to clamp a glass on the stem and / or cup so firmly that it runs exactly. A profiled grinding wheel then placed on the top of the floor would have to grind the asymmetries on one side; and this until all the seams have been sanded. This disproportionately removes glass material and the processing time is disadvantageously long.

There have also been searches for ways to remove the seam using sanding belts, the deflection roller of which has to be guided over the seam. However, these processes failed due to the high economic outlay on machines and tools.

A method of the type mentioned at the outset is known from US Pat. No. 3,160,994, in which frustoconical cups are pressed onto a multiplicity of honing stones, rotating with their open top facing downward, around their main axis. In the known case, the rotating body is rotated so that it can be pulled past the more or less held honing stones because the rim of the mouth of this glass vessel is to be processed. Each honing stone, in turn, is tiltable or pivotable about a pin and additionally about a pivot point during operation, in order to be able to avoid any out-of-roundness of the glass body, among other things. Machining the edge of the mouth in no way requires grinding work comparable to machining flat areas on the lateral surfaces of such a rotating body. To grind a dividing line or a burr at the edge of the mouth of a glass, the weak tool intervention of the known machine is sufficient, the mechanical movements and bearings of which also lead to a complicated structure. However, other problems arise when grinding lateral surfaces. Abrasive needs z. B. not to be fed, because the use of a honing stone is sufficient to remove an undesirable burr on the edge of the mouth of a glass.

It is also known from the patent specification US-A-1467517 to polish lenses, in particular pitch or wax being used as the polishing agent. It is described on p. 4 that the polishing tool is removed from the workpiece at intervals in order to supply an abrasive and water with a brush, but such fluid supply at intervals is disadvantageous in the same breath and a different type of fluid supply is recommended instead. It's also about that around the polishing of lenses, and the polishing tool should also be separated from the lens at intervals. Furthermore, the time between two such intervals is determined by making the work area dry; all conditions that do not occur according to the invention.

If one also considers the patent specification US-A-1 652494, it can only be stated there with regard to the design of the device for carrying out the method that a rigid tool is pressed against a kind of punctiform point on the solid body to be machined, which results from this a circumferential groove, groove or a band results, which is not comparable to a flat machining of a lateral surface of the glass body. In addition, abrasive is continuously brushed into the groove using a rotary brush and the holder for the tool is arranged essentially tangentially to the rotating workpiece. With the known machine, flat machining, in particular on the lateral surfaces of glass bodies, is not possible.

The same also applies to the method known from the patent DE-C-345 618. There, not even the tools are rigid but flexible, namely sponges or pieces of chamois leather.

The invention is therefore based on the object of making the known method also applicable for surface grinding and removal of burrs or steps of larger quantities of material.

This object is achieved according to the invention with regard to the method in that the working space between the tool and the outer surface of the solid body is supplied with flowable abrasive and the tool is pressed periodically against the outer surface to be machined. In contrast to all known methods, flowable abrasive is, according to the invention, led into a work space which is attached to the lateral surface of a solid body, i.e. H. is planned to be distributed over a larger area. In addition, the tool is pressed periodically or, in other words, the pressure is relieved periodically. With the new method, it is possible to remove the seams on the glass bodies described above, which were created during the pressing, a shaping tool working here with the continuous addition of abrasive. The new method surprisingly enables the sutures to be removed in less than 30 seconds, preferably less than 15 seconds. One has fundamentally departed from the previous working principle for material removal, namely elastomers, elastic tools, e.g. B. to use rotating disks or the like, which are rigidly mounted. According to the invention, the tool resiliently follows the solid body to be machined by the resilient mounting. The tool can e.g. B. be a shaped body made of steel and thus you can remove longitudinal seams on goblet glass feet so far in a very effective manner and in a short time that they can no longer be easily determined optically. The glass produced in machine production, possibly fully automatically, thus has a quality and quality that could previously only be achieved by hand processing. The new process opens up a higher-quality market for machine glass, even though the economic advantages of pressing the glass base are not left out. Pressing gives you versatile design options, low manufacturing costs and bare surfaces. The surfaces are only partially roughened by grinding and can be restored to their bare surface in a very short time by polishing.

The great difficulties with the known methods and in the unsuccessful attempts in companies can u. a. thereby explain that the seam created during the pressing of the glass base is not a burr as such, but a step, so that a brief abrasion with fine abrasive belts, the guide rollers of which would run along the contour of the foot, with little contact pressure would not produce the desired effect .

Another, unusual path has been taken by the invention, according to which the tool is moved relative to the vitreous body under strong contact pressure, but is nevertheless mounted elastically. Despite the high contact pressures, it is advantageous if the solid body, ie the glass body, is rotated and the tool is mounted so that it can move in an elastically movable manner and is pressed against the solid body in places. Standing in space means avoiding swiveling or tilting movements, as a result of which the overall structure of the machine according to the invention can be made considerably more robust. Although the tool could be pressed onto the entire surface of the body to be machined at the same time, only a partial contact is sufficient due to the rotational movement, which among other things results in the advantage of a smaller moving mass. Compared to the device for carrying out the method of the known type described at the outset, which also has a turntable for receiving and fastening the solid body and an elastically mounted, rigid tool pressed onto at least part of its surface, the device according to the invention is characterized in that that the holder of the tool is radially adjustable with respect to the axis of rotation of the workpiece and the tool has a sector-shaped working surface which can be placed on the lateral surface of the workpiece. Although the sector shape of a work surface is known per se from the prior art, what is new is the machining of the outer surface and thus the creation of a sector-shaped work surface on an outer surface of the workpiece, e.g. B. a hollow glass. in the In contrast to the lateral outer surface of a glass is the rim of the mouth, which cannot be described as the outer surface. In addition, the tool can be guided and supported with more compact means due to the radial deliverability of the holder, so that the high contact pressures required for surface grinding can be applied more easily with a robust machine! Due to the elastic mounting of the tool, it deviates by a small amount in all spatial directions, but still exerts considerable contact pressure on the surface to be machined, so that the seam, which is designed as a step in cross-section and which appears to the observer like a ridge, in a very short time Time can be removed. Since the surfaces of the workpiece and tool adapt optimally at every moment of rotation and thus no peak loads occur, as would be the case with rigid storage, both the tool and the glass body to be machined are largely protected, despite the strong contact pressure .

A tool with the features mentioned above can have a wide variety of contours, i. that is, the invention can also be used to grind or polish surfaces that are on machine-made, e.g. B. pressed goblets, especially their feet.

The rigid tool, which may be made of steel, can be shaped so complicated by machining, pressing or casting that any conceivable contour can be achieved. In this way, any useful tool can be produced with simple means. If the rigid part as a tool has a complicated contour in negative form, which corresponds to the positive contour of a workpiece to be machined, it is understandable that all desired machining operations can be carried out with a surprising effect and in a short time.

It is also advantageous according to the invention if channels are provided in the tool for the supply of abrasives. Because the tool is kept essentially stationary, liquid abrasive can be continuously pumped into the work area by means of hoses and lines, or else using brushes or sponges. Because the tool is pressed periodically onto the surface to be machined, a good supply of abrasive to the work area or the work surface is achieved.

However, it is also expedient if, according to the invention, the turntable is designed as a driven cup wheel and has a central support for setting up the solid body, which can be fixed by a clamping device. In the cup wheel, a larger supply of abrasive can be held in an annular recess around the center support, which can then be conveniently supplied to the processing area over short distances. The tensioning device can, for. B. be a pneumatic cylinder, the workpiece via an elastic, rotatably mounted pressure piece made of rubber, plastic or the like, for. B. a goblet glass, can be pressed onto the center support from above. The release can be periodically controlled preprogrammed.

In an advantageous further development of the invention, the tool is held by pressure cylinders via two rods running at an angle to one another, each with an elastic intermediate piece. These cylinders can be pneumatically driven and preprogrammed periodically controlled whenever z. B. after setting a glass body to be machined, the tool moves up to the surface to be machined and is lifted off again after machining.

The tool partially encloses the workpiece, preventing the tool from being pushed away.

The pneumatically driven cylinders therefore allow a pneumatically adjustable contact pressure. The pneumatics also have the advantage that when a protruding unevenness passes, the tool can dodge because the piston rods can be pushed a little bit into the cylinder while increasing the air pressure.

However, it can also be expedient if, according to the invention, a brush that can be moved vertically in an abrasive container is attached to the tool via a connecting device. This provides a particularly simple supply of abrasive.

It is also advantageous according to the invention if the abrasive agent container is designed as an annular channel arranged around the center support of the turntable, a spatula, which can also have passage openings, preferably being provided at an angle in the annular channel.

In a further embodiment of the invention, the tool has the contour in negative form of the workpiece to be machined, so that even complicated shapes can be created quite simply by the above measures.

If, according to the invention, the tool also encompasses the workpiece to be machined to an angle of at least 100 °, the tool is held in a stable manner, which at least partially at angles up to 160 °, even at an angle of 170 ° or even 180 ° can hold the workpiece. The tangential forces generated by the rotary movement of the workpiece, which try to push the tool away from the workpiece, are absorbed by the tool shape itself. This in turn allows the holder to be oriented more towards the application of pressures in the radial direction towards the general axis of rotation of the workpiece, because lateral forces occur relatively weakly.

It is also useful if the tool made of steel, preferably hardened steel, because then the material is removed preferably on the side of the workpiece and not on that of the tool.

• Fig. 1 verschiedentlich abgebrochen und teilweise schematisch eine Schnittansicht einer bevorzugten Ausführungsform einer Vorrichtung zum Schleifen oder Polieren eines Glaskörpers in der Darstellung eines Kelchglases,
• Fig. 2a die Draufsicht auf den als Topfscheibe ausgebildeten Drehteller im Betriebszustand, z. B. beim Schleifen,
• Fig. 2b die gleiche Ansicht wie Fig. 2a, jedoch in dem Zustand, wenn das Werkzeug vom Werkstück zurückgezogen ist,
• Fig. 3a schematisch einen Schnitt durch den Fuß eines Kelchglases parallel zur Bodenplatte mit Ansicht des in Arbeitsstellung befindlichen Werkzeuges,
• Fig. 3b die gleiche Ansicht wie Fig. 3a, wobei jedoch eine andere Ausführungsform eines Werkzeuges dargestellt ist, und
• Fig. 4 schematisch die Ansicht eines teilweise abgebrochenen Kelchglases mit in Arbeitsstellung befindlichen Werkzeugen unterschiedlicher Ausführungsform.

Further advantages, features and possible applications of the present invention result from the following description in conjunction with the drawings. It shows

• 1 broken off differently and partially schematically a sectional view of a preferred embodiment of a device for grinding or polishing a glass body in the representation of a goblet,
• 2a shows the top view of the turntable designed as a cup wheel in the operating state, for. B. when grinding,
• 2b is the same view as Fig. 2a, but in the state when the tool is withdrawn from the workpiece,
• 3a schematically shows a section through the base of a goblet glass parallel to the base plate with a view of the tool in the working position,
• Fig. 3b the same view as Fig. 3a, but showing a different embodiment of a tool, and
• Fig. 4 shows schematically the view of a partially broken goblet with tools in different positions in the working position.

In FIG. 1, a turntable 1 designed as a cup wheel is driven by the motor 4 via a rotary bearing 2 by means of a V-pulley 3 with a central support 1a as the workpiece carrier and an annular channel 1b arranged concentrically around the central support 1a.

In another embodiment, not shown here, the revolving rotary plate 1 with the central support 1 a is divided into two machine parts rotating separately from one another. On the one hand, the middle piece, the workpiece carrier 1a, is provided in a supported manner, on the other hand, the ring channel 1b is supported separately and is driven separately. He can e.g. B. revolve at a lower speed than the center support 1a a.

In the middle on the center support 1a, which serves as a workpiece carrier, a recess is provided as a centering, in which the foot 5a of the goblet 5 is to be processed. From above, the goblet glass 5 is pressed on with the aid of a cylinder 6 attached to the machine frame, a piston rod 6a and a pressure piece which is fixed with respect to the rotating clamping piece 6c by means of a rotary bearing 6b. In this way, the goblet glass 5 can be held more or less strongly in the centering on the central support 1 a by means of the air pressure that is set in each case.

The tool is shown in section in FIG. 1 and designated 7. 2a and 2b show a plan view of the tool 7, the same embodiment of the tool 7 being used in FIGS. 1 and 2, a plan view of a tool 7 half-embracing the workpiece 5a.

In the left half of FIG. 3a, another embodiment of a tool 7a is shown, which only encompasses the workpiece 5a over an angular range between 100 and 120 ° C. For this purpose, a similar tool 7b can be arranged opposite one another according to the dash-dotted line. The back pressure of both tools 7a and 7b can be adjusted to compensate.

3b shows a further different embodiment of the tool 7, which encloses the foot 5a of the goblet 5 by more than an angular range of 180 °, namely approximately 200 °.

Finally, FIG. 4 shows a further different embodiment of two tools 7a and 7b, which machine the foot 5a of the goblet 5 at different heights from opposite sides. Here, the tool 7a is pressed in the direction of the arrow 20 and the tool 7b in the direction of the arrow 21 on the foot 5a from opposite directions. This resulting pressure direction 20 or 21 results, depending on the embodiment of the machine, possibly by the direct pressure of a piston rod 8a, 10a or 10b, the contact pressure of which can be adjusted separately in a pneumatically controllable manner.

Looking at Fig. 1, it can be seen that the tool 7 is held by a horizontally arranged rod 10a via an elastic intermediate piece 11 by a pressure cylinder 10 and by a rod 8a via an elastic intermediate piece 9 by the pressure cylinder 8. It goes without saying that, depending on the contact pressure, the resultant lies more or less in the horizontal or vertical, so that the contact pressure is directed in the desired manner at the location of the foot 5a at which a particularly large amount of material is to be removed. For example, the contact pressure above can be selected a little stronger. It is preferred to use the specific, i.e. H. to keep area-related, contact pressure constant.

The tool 7 is thus pressed elastically against the foot 5a by the pneumatic pressure in the pressure cylinders 8, 10. If a protruding unevenness on the foot 5a runs towards the tool 7, this deflects in that the piston rod 8a or 10a is pressed into the cylinder 8 or 10.

By the correct regulation of the pneumatic pressure in the pressure cylinders 8 and 10 you can z. B. in Fig. 4 by the arrow 20 resultant of the contact pressure and contact direction, so that the removal of material on the workpiece takes place only in this desired direction, in such a way that the tool contour practically does not change. It goes without saying that a plurality of piston rods 8a, 10a can be provided and these can also be arranged at the most varied angles in order to About the pressure level in the pressure cylinders 8 and 10, which can be adjusted separately to adjust the resultant, ie the pressure in amount and direction.

The pressure cylinder 8 is fastened to the frame 14 via bolts 8b, to which the intermediate piece 11 with the rod 10a is also attached. On the side of the frame 14 opposite the intermediate piece 11, the piston rod of the pressure cylinder 10 is fastened, which is held on the base plate 17 of the machine via a bolt 10b. The frame 14 is movable to the right and left as shown in Fig. 1 by the action of the pressure cylinder 10, with the help of a secured against rotation longitudinal bearing 15, in addition to which the protective bellows 16 is shown, the penetration of dirt, for. B. abrasive, prevented in a groove storage, not shown. With the frame 14, the rods 8a and 10a and thus the tool 7 move relative to the base 5a of the goblet 5 held on the central support 1a. Furthermore, the cylinder 12, which is attached to the frame 14 via the bracket 14a, also moves with the frame 14 A brush 13 is attached to the free end of its piston rod via an adjustable clamping or screwing device 12a. From this, during the grinding process in the illustration of FIGS. 1 and 2a, abrasive runs onto the foot 5a to be processed. In the illustration in FIG. 2b, by moving the frame 14 together with the part attached to it to the right, the cylinder 12 with the brush 13 has also moved to the right and is then located above the ring channel 1b filled with abrasive 18.

In Figure 2a, an obliquely positioned spatula 19 with through holes is also shown. It serves to homogenize the abrasive in the ring channel 1b. According to the schematic illustration, it is stationary, while the abrasive 18 rotates together with the ring channel 1b in the direction of the curved arrow 22 shown in FIGS. 2a and 2b. The spatula 19 advantageously prevents the heavy constituents of the abrasive from settling on the bottom of the annular channel 1b.

In the embodiment shown in Fig. 4, the tool 7a z. B. from. Hardened steel and the tool 7b arranged on the opposite side as a counterpressure made of slidable plastic. The embodiments described above show that the tools 7a, 7b, if necessary, from different directions and at different times on the foot 5a, i. H. the workpiece to be machined.

In operation, ie for grinding off the step which appears as a rib on the base 5a of the goblet 5, the abrasive is first filled into the ring channel 1b, then the goblet 5 is placed on and clamped by actuating the cylinder 6 with the aid of the clamping piece 6c. Then one moves the abrasive-filled P ⁱ nsel 13 by operating the cylinder 12 from the annular channel 1b out, so that, viewed from above, the state is reached in accordance with Fig. 2b. Then the frame 14 is moved to the left by actuating the pressure cylinder 10, so that the operating state shown in FIGS. 1 and 2a is reached. By correctly regulating the pressures in the pressure cylinders 8 and 10, the correct resultant for the pressure that the tool 7 exerts on the foot 5a is achieved. The motor 4 rotates the foot 5a for about 10 seconds under the tool 7, after which the unsightly step is essentially ground down. The pressure cylinders 8, 10 are actuated so that the tool 7 can be moved with the brush 13 according to the dashed arrow 23 in FIG. 2a into the position according to FIG. 2b. Then the cylinder 12 is actuated, the brush 13 dips into the abrasive 18 in the ring channel 1b, fills up, and the work cycle begins again.

It is understood that the rotation of the ring channel 1b continuously moves the abrasive 18 on the stationary, inclined spatula 19 and through its through holes, so that the heavy components cannot settle on the bottom of the ring channel and homogenize the abrasive is guaranteed.

Claims (11)

1. A method of grinding curved surfaces of non-metallic solid rotationally symmetrical bodies (5), in particular glass bodies, by means of a tool (7) which is resiliently movably held pressed firmly against the rotated solid body (5), wherein the tool (7) is partially adapted to the surface to be treated, characterised in that grinding agent which is capable of flow is fed to the working space between the tool (7) and the peripheral surface of the solid body (5) and the tool (7) is periodically pressed against the peripheral surface to be treated.

2. Apparatus for carrying out the method according to claim 1 comprising a turntable (1) for mounting and securing the solid body (5) and a resiliently mounted, rigid tool (7) which is pressed against at least a part of the surface of said body, characterised in that the holder (8a, 10a) of the tool (7) can be radially advanced relative to the axis of rotation of the workpiece (5) and the tool (7) has a sector-shaped working surface which can be applied against the peripheral surface of the workpiece (5).

3. Apparatus according to claim 2 characterised in tnat passages are provided in the tool (7) for the feed of grinding agent.

4. Apparatus according to claim 2 or claim 3 characterised in that the turntable (1) is in the form of a driven cup wheel and has a central support means (1a) for mounting the body (5) which can be secured by a clamping means (6).

5. Apparatus according to one of claims 2 to 4 characterised in that the tool (7) is mounted by pressing applicator cylinders (8, 10), by way of two rods (8a, 10a) each having a resilient intermediate member (9, 11), the rods extending at an angle to each other.

6. Apparatus according to claim 2, claim 4 or claim 5 characterised in that a brush (13) which is movable perpendicularly in a grinding agent container (1, b) is secured to the tool (7) by way of a cennecting means (14, 14a).

7. Apparatus according to claim 6 characterised in that the grinding agent container is in the form of an annular channel (1 b) arranged around the central support means (1a) of the turntable (1).

8. Apparatus according to claim 7 characterised in that a spatula member (19), preferably with through openings therein, is disposed in an inclined position in the annular channel (1b).

9. Apparatus according to claim 2 characterised in that the tool (7) has the contour in negative form of the workpiece (5) to be ground.

10. Apparatus according to one of claims 2 or 8 characterised in that the tool (7) engages around the workpiece (5) to be ground, over an angle of at least 100°.

11. Apparatus according to one of claims 2 to 10 characterised in that the tool comprises steel.

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