US111688A - Improvement in electrotype-dies or molds for molding plastic materials - Google Patents

Description

aura saw DAVID SORYMGEOUR, OF FOXBOROUGH, MASSACHUSETTS.

Letters Patent No. 111,688, dated February 7, 1871.

IMPROVEMENT m ELECTROTYPE-DIES OR MOLDS FOR MOLDING PLASTIC MATERIALS.

The Schedule referred to in these Letters Patent and making part of the same.

To all to whom these presents shall come.-

Be it known that I, DAvID- SonYMeEoUR, of Foxborough, in the county of Norfolk and State of bias sachusetts, have made an invention of a new and useful Mode of- Obtaining Electrotypc-Dies or Molds for producing articles of ornament or use from animal or vegetable pulp; and do hereby declare the following,

for a patent for which has. been recently allowed by tbe United'States Patent Ollie-e.

In order to carry out this invention of Curtiss it becomes necessary to procure a matrix which shall conform, in the most minute details, to the object of utility or art which it is intended to reproduce in large numbers, at low cost, from paper pnlp; and

;-1\I y invention is intended to produce in an economiealmanner a mold or matrix forthis purpose; and to this end I proceed substantially as follows:

First, I procure or fashion a model of a certain object of an artistic or useful nature, whether a pictureframe, an ornament forjfine furniture, a molding, or any of the thousand-abd-one subjepts which come within the scope of the useful arts, suchmodel or design being fashioned in wood, wax, gutta-percha, plaster of Paris','composition,- or any material or substance which may be worked to the best advantage;

Having acquired a suitable model, I apply a film of wax to the blank or obverse side thereof, in order to obtain a convenient and inexpensive means of attaching it toa case or'form of copper, this case or form serving to insure the correct position of the model in the electric bath-in which it is immersed.

The case or form last named is produced from sheet.- oopp er, and of a general outline to conform to the .principal curvatures or boundaries of the model, and,

when completed, is entirely incased in a thin jacket of wax. I now attach the model to this copper form by heating and fusing the wax upon the latter, and applying theb'ase or back of the model to it, to which it will firmly adhere when the wax solidifies.

Having thus prepared and united the model and copper base, a suitable varnish is prepared by dissolving wax in naphtha, and a thin coat of such varnish is-applied with a soft brush to the exterior or ornamental face or portions of the model which-are not covered by wax, the nature of this varnish causing it to dry in a short time, while its consistency is or should be such that the lines, or irregularities, or traccry of the model, no matter how minute or finely out, shall retain their primitive condition.

In pursuance of the objects of the invention, 1 next an equivalent substance, which will adhere thereto in sufficient quantity to cover all its irregularities or sin nosities, a certain degree of rubbing with a brush or other soft object being applied to produce a polished surface, the purpose of this dress of plumbago being in part to prevent adhesion of the copper deposit to the model, but mainly as a nictallic vehicle whereby the copper in the bath is induced to creep on and over the model.

A-ledge or inclosing-wall of wax should nowbe applied to the edge of the copper form or base, in order to prevent waste of copper in the electrotyping process to which it is subjected, and the whole immersed in the bath of an electric battery, the suitable connections being made, by which means a thin deposit of copper is, in a given time, laid upon the'glazed surface of the model, the plumbagointervening.

\Vhen the copper has acquired therequisite degree of thickness, which will ordinarily result in from three to five days, thewhole is'to'be. removed from the bath and plunged in hot water, by which means thewax connection between the model and the copper form is sundcred, and the two separated, the wax being in the act entirely cleaned from oil both.

At this stage of procedure I remove the model from the copper shell which surrounds it, this removal of the model being elfected in various ways, according to the nature of the material of which it i's'composedif of wax, gutta-percha, or .other easily fusible substance, by melting; if of plaster of Paris, 8w, by breaking-thus leaving a thin and delicate negative mold or matrix of copper, which is a perfect fac stm-ilc of the original model, even to the most minute details.

I next apply to the interior or ornamental face of! the matrix a glazing of any suitable substance,- which shall protect it from the accidental adhesion of tin, of which a thin film is to be applied to the obverse or back side of the matrix by the ordinary elcctrotyping process, this film of tin being the medium whereby to subsequently solder the matrix toa suitable base or means of support.

Continuing this operation, I now procure a suitable vessel or flask of cast-iron, of such extent as to easily contain the mold, the interior of this flask being of a size and form to produce a plunger or tenon from a molten metal poured within it, which shall fit the. socket of the hydraulic press, in which pressure is applied to the contents of the mold, a filling-orifice being made in the bottom of theilask, through which the molten metal is poured, as hereinafter explained.

At this stage, after procuring a flask, as above stated, I'obtain a block or mass of wood, or a suitable soft and easily-carved or manipulated material, the outline of this block in horizontal section being equal to the horizontal area of the interior of the flask which it fills. I next carve or impress on the upper surface of this block a cavity or depression of a form and depth corresponding to the exterim or obverse side of the copper mold, such mold being deposited in this cavity while the block rests upon the bottom of the flask, it being observed that the space intervening between the outer boundary of the mold and the inner wall of the flask is of a depth equal to the thickness of the wall of the metallic backing which we are ,now about to which leaves the flask, with its contents, resting upon said plate. I now remove the flask, leaving the contents standing upon the plate, the block or support being uppermost, after which I remove the block caree fully from ed the copper matrix, which latter remains adhering to and resting upon the sand core, which has taken the impress of the matrix. From this point the completionof the operation is simpleaud easily understood: the flask, bottom up, is returned to place ever and about the sand core and matrix, and firmly bolted to the plate upon which the latter rests, and a quantity of molten metal poured into the flask through the orifice in its bottom, such metal filling the flask 'and the space between its inner periphery and the oxterior wall of the matrix which the removal of the block or core-box created. The metal, having become cool, is removed from the flask, the sand, core cleaned from thematrix, and thelatter, with such metal backing adhering-to it, being in a state ready for use.

The pedestal or body of metal deposited about the exterior of the mold, as above stated, constitutes a solid and durable support or backing to the same, without which the 1nold,.owing to its frail character, could not be successfully used.

The base of this backing orpedesial is, as before stated, of a size and form to fit the socket of the press in which the mold 'isnsed. v

Any suitable substance. such as pulp from animal and vegetable fiber, forced into the matrix by hydraulic or other pressure will assume the identicalform and impress of the same.-

I am aware of the existence of certain improvements in clectrotype-dies for making imitation-straw States -'No. 61,074,'in which is described a process somewhat analogous'in principle, but totally different in detail from mine..'- In this patented process a flat plate of copper was employed, upon which the model in straw was secured ;-'and, if this model was of a curved or irregularexterior, as, for instauce,.the rim of a hat, a small. portion only of such exterior would touch the place, generally, at but two isolated points. As the copper depositcd'by the electric battery-upon the exterior of the mold can creep upon the same only at these twopoints, the process of depositing a copper shell of the requisite thickness was a matter of considerable time. I

By the employment of a copper base, of a form to adapt itself to the curves or irregularities of the outline of some principal part of the model, I obtain a union of two large surfaces, bywhich the deposition of the copper upon the model is greatly hastened.

By'the employment of the flask and core-box I obtain a very great advantage over the "above-named patented process in producing the sand core or support for the matrix hereinbei'ore alluded to, since I am enabled to mold the shoulder of this core directly in consonance witltthe outline of the principal side of the model, which, in the case of a straw hat, is the under side of the rim, while in the patented process above named the requisite amount of metal is removed by the labor and expense of chipping and reducing with a chisel.

Claim.

1 cla1m- The mode herein described of producing a matrix or mold, and also-a support or backing for the same.

' DAVID SGRYMGEOUR.

goods, as shown in Letters Patent of the United.