DE2341329A1 - Finish machining of toric faces - uses a plastic shell with toric working face selectively coated with working material - Google Patents

Abstract

The finish machining of toric faces is esp. for producing lens glass etc., where a device for such machining is in the form of a toric shell for toric ring-grinding-and polishing-machines. A plastic shell has a toric working face which is selectively coated with layers of equal thickness of a grinding or a polishing matl. Specif., the working face is coated with plates of a grinding matl., and polishes the convex face of a workpiece. The machine has its work faces reciprocated at approx. 400 cycles per min. in a pendulum motion. The working matl. may be formed in scales with areas between to receive removed matl.

Description

Dipl.-Ing. G. Schllebs _{6T D ,? Mftad} t ciaudiusweg i7A

Patent attorney phone (06151) 46753

Postal checking account: Frankfurt a. M. 111157-606 Bank details: Deutsche Bank AG., Darmstadt Telegrams: inventron

.'Ji dp. s

German Patent Office

-Q OO lynch 2
Z ^ eibrückenstr. 12th

Your sign Your letter My sign S 113 ^Ta 0 13 · 8th 1973

Subject: Patent registration Applicant: Wilhelm H. Spira, Darmstadt

Device for finishing toric surfaces.

The invention relates to a device for fine machining of toric surfaces in the form of a toric shell for toriring grinding and polishing machines, such as those required for the manufacture of spectacle lenses.

Known Toriring machines used for grinding a convex toric lenses in the mass production of a con- _<k ave shell of cast iron, the pressed with ball pins of an oscillated shell holder of the machine with adjustable contact pressure against the fixed to the circumference of a rotating drum workpieces, the glasses will.

When finishing concave toric glasses, the Jars are arranged along the inner circumference of a rotating ring and the working surface of the bowl is convex. The toric surface of this cast-iron bowl always has the same main radii as the toric surface of the workpiece, and both surfaces are created on the same cutting machine, such as in the DT patent application P 22 58 152 is described. So while grinding the surface of the cast-iron shell itself attacks, an aluminum dish is used for subsequent polishing, the surface of which is covered with a felt

509811/0035

The fee schedule of the German Patent Applicants applies for the contract relationship. Jurisdiction for performance and payment ι Darmstadt Conversations on the telephone have no legally binding effect I

Letter dated March 13, 1973 sheet 2 Dipl.-Ing. G. Schliebs

to the German Patent Office, liünchen patent attorney

is; the main radii of this polishing bowl must therefore be different from those of the grinding bowl by the thickness of the felt covering, i.e. two different bowls and the one used for this must be produced for the pain treatment Machine tool must be converted. In addition, the grinding cup must be reworked from time to time to restore the geometric shape of your worn-out grinding surface.

The object of the invention is therefore to create a device of the type mentioned at the outset, which in a basic version Can be used for both grinding and subsequent polishing by using the for the two Machining process provided surfaces required will.

According to the invention, this object is achieved with a plastic shell, the toric work surface of which is optionally provided with layers the same thickness of a grinding or a polishing material is occupied. This plastic tray can be used in simpler Way and in much less time than on a machine tool in an injection mold, and it will only one shell shape is required for both machining operations of grinding and polishing, the main radii of which are around the thickness of the covering layers is greater than the main radii of the workpiece.

While a polishing felt can be applied to a curved surface without difficulty, it initially appears difficult to apply a layer of a hard material to this surface in the same way. However, this difficulty can be avoided if, according to a preferred embodiment of the invention, the working surface of the plastic shell is covered with plates of an abrasive material, for example made of the cast iron commonly used.

509811/0035

Letter from BIaH 3 Dipl.-Ing. G. Sdiliebs

to the German Patent Office, Munich Patent Attorney

As soon as a certain wear and tear of the covering layers has occurred, these can be detached and replaced with new ones, while the plastic shell can be easily reused.

In the following the invention is explained using an exemplary embodiment which is shown in the drawing. In this demonstrate

Fig. 1 shows a grinding cup and

Fig. 2 shows a polishing bowl according to the invention;

Fig. 3 partial cross-sections through both shells.

Both shells consist of a plastic injection molded part 1, its main radii R ^ and E ^ its toric concave surface and are larger than the main radii by an amount / \ - p of the workpiece to be finely machined. A steel plate 2, the spherical shell-shaped one, is injected on the back Recesses 2.1 for receiving the ball pins on the Has the shell holder of the toriring machine. Channels 2.2 go from these recesses to the front surface, through the cooling liquid can be supplied as is known.

For use as a grinding bowl (Fig. 1), the "front surface is _{covered with plates 3 of the thickness A R} , which are glued on. When the plates are processed in the grinding process, they can be detached and replaced by new ones, ie the shell itself needs - In contrast to the usual cast-iron grinding bowls - cannot be reworked.

For use as a polishing cup (Fig. 2), the front surface is 4-thick with a felt cloth in a known manner Δ-β proven.

509811/0035

Letter from page 4 Dipl.-Ing. G. Sdiliebs

to the German Pave ο camouflages , Künchen patent attorney

While the workpieces are being processed, the shell is controlled by a compressed air cylinder with a finely adjustable pressure pressed against the workpieces moving past it on a circle, and at the same time they become pendulum oscillations issued at a frequency of 400 strokes / min and more. While up to now 400 strokes / min was the upper limit for cast-iron shells were because of the already considerable inertia forces that occur, the considerably lighter ones according to the invention can Plastic shells vibrate at a much higher frequency without parasitic vibrations or increased bearing wear occur, i.e. the processing time can - in addition to the other advantages of the invention - be significantly reduced will.

While the drawing shows a tool for fine machining convex-toric spectacle lenses, the invention can also be used in accordance with concavo-toric spectacle lenses or the like , where the tool then has a convex-toric surface.

509811/0035

Claims (4)

Letter dated August 13, 1973 page 5 DIpL-Ing. G. Sdill.bt _to the German Patent Office ;, Munich patent attorney Claims Λ Device for fine machining toric surfaces in the form of a toric shell for toriring grinding and polishing machines, characterized by a plastic shell (1) whose toric working surface is optionally covered with layers (3, 4) of the same thickness of a grinding or a polishing material. 2. Apparatus according to claim 1, characterized in that the working surface of the plastic shell as a grinding shell with plates (3) of an abrasive material, preferably Cast iron, is occupied. 3. Apparatus according to claim 1, characterized in that the working surface of the plastic shell as a polishing shell is covered in a known manner with a polishing felt. 4. Apparatus according to claim 1, characterized in that a steel plate on the back of the plastic shell (1) (2) is arranged with ball seats (2.1) for receiving the ball pins of the shell receptacle of the machine. 50981 1/0035 Blank page