US2985910A - Mould - Google Patents

Description

y 30, 1961 J. c. VAN HOUTEN 2,985,910

MOULD Filed May 13, 1958 ///////////////////,L J //////////Z 4 3 u 1 FIGJ Eva FIGLZ.

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AGENT United States Patent ()fi ice MOULD Jan Christotfel van Houten, Baarn, Netherlands, assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed May 13, 1958, Ser. No. 734,899

Claims priority, application Netherlands May 25, 1957 4 Claims. (Cl. 185.3)

The invention relates to moulds particularly for gramophone records.

In the co-pending US. application Serial No. 720,687, filed May 11, 1958, in which I am a co-inventor, a mould is described which comprises an upper block and a lower block carrying thin electro-formed matrices and intended for pressing gramophone records labelled at both sides. The pressing blocks are articulated together in such manner that these articulations permit not only rotation of the blocks relatively to each other but also a limited movement of one of the blocks parallel to the other block and away from this block or towards this block, while the pressed record has a central aperture, for which purpose one of the blocks has a preferably detachable pin fitting in an aperture of the other block when the pressing matrix is closed. The pressing material, either in the form of a thin pre-sintered wafer or a pre-heated thick cake may be disposed between the blocks. Naturally the thick cake, which ofiers advantages over a thin wafer in practice, has a diameter much smaller than that of the wafer. When using the thick cake, the centering pin piercing the aperture in the record should be comparatively long. After placing the cake on the pin, the cake has to be provided with a label, which should also be centered and held by the pin until the record has hardened. Finally, the pin should project beyond the cake so as to sufiiciently center the upper block when closing the mould. However, this long pin has a disadvantage in that it is difiicult to remove the record from the pin.

A pin satisfying all these requirements is, in accordance with the invention, characterized in that with a mould comprising a pin of the type referred to, this pin has a round cylindrical form, the upper part and the lower part of which are of equal and permanent diameter, while the intermediate cylindrical part has a generatrix which is convex relative to the center line of the pin. Such a pin may have the required length .while the record comes ofi easily.

In one form the invention, the lower part of the pin, by which is meant the part projecting above the block in which the pin is secured, is preferably slightly longer than the spacing of the pressing blocks when the mould is closed and the record has been pressed. In this manner, it is achieved that the centering hole of the upper block is closed by the pin during the last pressing period and the hardening period, thereby preventing the material from being pressed upwards and maintaining centricity of the upper block.

In a further form of the invention, the length of the convex part inclusive of the length of the lower part is advantageously slightly smaller than the thickness of the moulding material introduced into the mould prior to the pressing operation, inclusive of the label. These measures ensure the centricity of the label.

Finally, it is advantageous for centering the upper block if, in a further embodiment of the invention, the length of the projecting part of the whole pin above the block exceeds the thickness of the moulding material introduced into the mould prior to the pressing operation.

. In order that the invention may be readily carried into effect, an example will now be described in detail with reference to the accompanying drawing, in which Fig. 1 is a sectional side view of a mould for pressing gramophone records, shown before the pressing operation with a cake of moulding material in place,

Fig. 2 is a sectional view of the mould of Figure 1, but after moulding-and hardening the record, and

Fig. 3 is a side view of a portion of the mould shown in Figures 1 and 2 with a pivot construction according to the above-mentioned patent application.

The reference numeral 1 designates a lower block carrying an electro-forrned matrix 2. Into this block a centering pin 3 is screwed. This pin has a round cylindrical part 4, a cylindrical part 5 convex relative to the center line and a round cylindrical part 6 having the same diameter as that of the part 4. A paper label 9, a cake 10 and a paper label 11 are disposed between the lower block 1 and the upper block 7 which also comprisesan electro-formed matrix 8.

In order that blocks 1 and 7 may have a limited movement parallel to each other, a mold is provided with a pivot of the type described in the above-mentioned copending patent application and as shown in Figure 3 of the drawings. More particularly, two resilient strips 12 have one end secured to the blocks 1 and 7 and have their other ends secured to blades 13 and 14 of a pivot 15.

From Fig. 1 it is seen that the length of the part of the pin 3 indicated by A is smaller than the thickness of the cake prior to the pressing operation, thus achieving a satisfactory centering of the upper block before the pressing operation, since the part 6 provides for the centering. Moreover, the label 11 is maintained and centered satisfactorily.

It should be noted that in the drawing the label 11 is shown on a scale which is much greater than the scale of cake 10. If label 11 were shown on the same scale as cake 10 it would be barely discernible, the lower surface of cake 10 would appear to touch the upper surface of the matrix 2 and distance A would appear to be less than the thickness of the cake 10.

The length B of the part 4 of the pin 5 exceeds the spacing of the pressing blocks with the blocks closed and record pressed, as may be seen from Fig. 2. In this manner, the upper block remains centered and, moreover, the aperture of the upper block is closed so as to prevent the moulding material from escaping through it.

The particular shape of the part 5 of the pin has still further advantages. If the Whole pin is shaped as shown in the drawing, it is easier to remove the pressing from the mould, than if it has the same diameter throughout. Further such centering pins are, in general, subject to considerable wear in practice, whereas the pin according to the invention offers much more resistance to wear.

What is claimed is:

1. A mold particularly adapted for molding gramophone records comprising upper and lower blocks pivotally connected together to permit rotation and translation of the blocks relative to one another, a pin member connected to one of said blocks and extending into an aperture into the other block, said pin having upper and lower cylindrical portions of like diameter and an intermediate cylindrical portion the generatrix of which is convex relative to the center line of the pin.

2. A mould as claimed in claim 1, in which the length of the lower portion of the pin slightly exceeds the spac- Pa tented May 30, 1961,

3 4 ing of the moulding blocks with the mould closed and the of the projecting part of the whole pin above the mouldrecord pressed. ing block exceeds the thickness of the moulding material A mould Claimfid in Claim in Which the length introduced into the mould prior to the pressing operation. of the intermediate portion'and the length of the lower cylindrical pin portion is slightly smaller than the thick- 5 References Cited in the file of this patent ness of the moulding material, as introduced into the UNITED STATES PATENTS mould prior to the pressing operation, including the thickness of a label, 1,401,966 Davis et a1. Jan. 3, 1922 4. A mould as claimed in claim 1, in which the length 2,839,306 Bayless June 17, 1958

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