US3747440A - Preparing master pattern for producing casted raised figures - Google Patents

Abstract

A master pattern for the casting of raised figures such as lettering on a plaque or plate is produced by hobbing the figures into a material which has been preformed with suitable void or open spaces to accommodate the material displaced during hobbing.

Description

United States Patent 11 1 Camilleri 1451 July 24, 1973 PREPARING MASTER PATTERN FOR PRODUCING CASTED RAISED FIGURES [76] Inventor: Thomas M. Camilleri, 277 Ave. W.,

Brooklyn, NY. 11223 [22] Filed: Oct. 5, 1971 [21] Appl. No.1 186,690

[52] US. Cl 76/107 R, 29/527.5, 29/DIG. 23,

29IDIG. 30, 264/219, 264/313 [51] Int. Cl B2lk 5/20, B23p 25/00 [58] Field of Search 76/107 R;

29/DIG. 23, DIG.'30, 527.5; 264/219, 313

[56] References Cited UNITED STATES PATENTS 991,747 5/1911 RaWsthorne 76/107 R 11 2,323,949 711943 Vosburg 3,077,797

2/1963 Payne 76/107 R.

307,169 10/1884 Bisson 29/D1G. 30

556,591 3/1896 Taber 264/219 X 1,985,300 12/1934 Shaw 29/D1G. 30

2,039,488 5/1936 McDonald 264/313 X 2,757,372 7/1956 Chambon 29/D1 G. 30 3,534,440 10/1970 Roberts 264/219 X 891,499 6/1908 Morningstar 29/419 Primary Examiner-Charles W, Lanham Assistant Examiner-D. C. Reiley, III Attorney-Morgan, Finnegan, Durham & Pine [57] ABSTRACT A master pattern for the casting of raised figures such as lettering on a plaque or plate is produced by hobbing the figures into a material which has been preformed with suitable void or open spaces to accommodate the material displaced during hobbing.

8 Claims, 11 Drawing Figures PATENIEDJULZMSIS SHEET 1 0F 3 I INVENTOR. A! 77 0045 M. C'AM/LZER/ PATIENIEB M2 SHEET 2 0F 3 m V 6 0 0 0 m O 0 A 0 0 FIG.4

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INVENTOR. I flaws/1% CAMILLER/ FIG. 7

PATENYEUJULMISH sum 3 or 3 if A "i FIGS FIG. 10

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PREPARING MASTER PATTERN FOR PRODUCING CASTED RAISED FIGURES BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to the casting of raised figures such as lettering on metal surfaces or other material, and more particularly to a method wherein a negative master is produced by hobbing.

I-Ieretofore, the casting of raised figures such as lettering found on plaques and plates has required the use of a master pattern produced by engraving. The engraving procedure is a long and costly one requiring skilled and trained craftsmen. It has been the experience that the casting process for producing raised figures is only feasible in situations calling for the production of items in mass quantities where the initial outlay of cost for skilled engraving can be readily absorbed. Where such was not the case, the cost of engraving became exorbitant.

In situations where casting has heretofore not been feasible, embossing, indented, or scratch letter, (approximately 0.003 inch depth) processes have been employed. Embossing, indented, and scratch lettering are suitable only in connection with sheet materials and all three procedures are qualitatively not as desirable as casted raised letters in terms of the end product produced.

The hobbing technique has been tried'as a means for implementing the casting of raised letters, but in the past has produced wholly unsatisfactory results in plaque or plate lettering and similar situations requiring accuracy and uniformity in the figures. Distortion in the lettering has invariably resulted. The pressure applied during the hobbing step results in the hobbed material being displaced upwardly and inwardly distorting and deforming the lettering produced.

It is an object of the present invention to provide a method for producing raised lettering by casting which will render the casting procedure competitive with all other techniques regardless of the number or quantity of articles to be produced. More particularly, it is an object of the invention to provide a method for producing a negative master for casting by the technique of hobbing in lieuof engraving whereby qualitative results comparable to engraving are achieved.

Briefly and generally, the foregoing and other objects, features and advantages which will become apparent herefrom are achieved in accordance with the invention by a method in which the material to be hobbed is first preformed with a suitable distribution of void or open spaces, preferably on the surface as by knurling, to accommodate the flow of material displaced by the imprint formed during hobbing. In accordance with a further principle of the invention, the accommodating voids must have a volume in' the region to be occupied by the lettering and a peripheral region extending outwardly therefrom a distance equal to the thickness of the material being hobbed at least equal to the volume of imprint to be formed. The resultant negative imprint in the master is free of all'distortion and constitutes an exact mirror image of the letters to be cast.

BRIEF DESCRIPTION OF DRAWINGS Having summarized the invention, there follows a detailed description thereof with reference to the accom- 2 panying drawings forming part of the specification, of which:

FIG. 1 is a perspective view, partially in section, diagrammatically illustrating a knurling apparatus constituting the presently preferred means by which suitable accommodating voids are produced in a master workpiece in accordance with the invention;

FIG. 2 is a sectional view diagrammatically illustrating the apparatus of FIG. 1 closed in the process of knurling the workpiece surface in accordance with one embodiment of the invention;

FIG. 3 is a view similar to FIG. 1 diagrammatically illustrating the distribution of surface voids produced by knurling pursuant to the procedure illustrated in FIG. 2;

FIG. 4 is a view similar to FIG. I diagrammatically illustrating apparatus for impressing a negative or mirror-image imprint of raised letter forms on the knurled workpiece surface in accordance with the invention;

FIG. 5 is an enlarged fragmentary sectional view taken on line 5-5 of FIG. 4 illustrating in detail the surface voids formed therein by knurling;

FIG. 6 is a view similar to FIG. 2 in which the raised letter forms are being hobbed or impressed into the knurled surface in accordance with the invention by the apparatus of FIG. 4;

FIG. 7 is a view similar to FIG. 3 illustrating the negative or mirror-image imprint of the raised letter forms hobbed in the knurled surface pursuant to the step of FIG. 6;

FIG. 8 is a sectional view taken on line 8-8 of FIG. 7 further diagrammatically illustrating the mirrorimage imprint of the raised lettering formed in the knurled surface;

FIG. 9 is a diagrammatical view illustrating the final step of the improved casting process of the invention in which the negatively imprinted master of FIG. 8 is placed in a die-casting apparatus;

FIG. 10 is a diagram illustrating the manner in which the critical knurling area is determined in accordance with the invention; and

FIG. 11 is a perspective view of a die-cast plaque having lettering produced in accordance with the invention as illustrated in FIGS. l10.

DETAILED DESCRIPTION Turning now to the accompanying drawings in which like reference characters are employed to designate like parts throughout, means are illustrated in FIG. 1'

for forming suitable accommodating voids in accordance with the invention by knurling a workpiece 20 which is to serve as the casting die or master. While surface knurling, i.e., the forming of surface depressions, is the presently preferred means for carrying out the invention by virtue of its simplicity, it is contemplated that any means by which a suitable void distribution can be formed, either on the surface of in the body of the workpiece, will be satisfactory and useful in the practice of the invention.

As illustrated, the knurling means can conveniently comprise'a conventional hydraulic press having a workpiece holder 21 and a cooperative overhanging press device 22. Such apparatus is well known in the hobbing art and further description herein is unnecessary. A typical knurling tool 23 is illustrated in FIG. 1 suitably secured to the press device 22 and supported thereby directly above the workpiece 20.

As best shown in FIG. 2, the workpiece is positioned in a recessed area or cavity 24 in the holder 21. The workpiece material, thus confined, is prevented from distorting around its perimeter or bottom surface during the knurling step.

In FIG. 2, the press device 22 is closed on workpiece holder 21 with sufficient force F to impress the surface configuration of knurling tool 23 into the exposed surface of workpiece 20 to the desired depth of knurl. Assuming, for example, that the tool is pressed into the workpiece 0.025 inch, the workpiece material will rise into the openings of the knurling tool approximately 0.020 inch. As a result, the workpiece material of the example will have increased in overall thickness approximately 0.020 inch and a series of uniformly spaced openings of voids 25 will have been formed in the workpiece surface as illustrated in FIGS. 3, 4, and 5.

It is believed that a percentage of the material of the workpiece is compressed or compacted during the knurling step, but the rest of the displaced material flows upwardly to increase the overall thickness of the workpiece. The material displaced by the knurling tool where the surface voids are formed displaces the adjacent material and so on with the increase in thickness approximately equal to the volume of the voids formed. The configuration of the knurling tool and the depth of the knurl is determined by the natureof the figures to be hobbed.

In accordance with a principal of the invention, the voids formed in the material must have a volume at least equal to the volume of figures to be hobbed or im- .the volume of the hobbed figures.

The 1:1 ratio of voids to hobbed volume represents the critical minimum below which distortion will begin to occur. The 2:1 ratio provides a safe tolerance to avoid distortion.

As illustrated in FIG. 10, the critical knurling area constitutes the area occupied by the lettering and an additional peripheral region extending a distance from the lettering equal to the thickness of the material. This relationship of material thickness to knurling area pertains regardless of the nature of the material itself. It has been found that the material displaced during the hobbing step flows or displaces downwardly and outwardly at an angle of 45 from the surface. By confining all of the surfaces of the workpiece material except the upper or exposed surface during hobbing, ultimately displacement-will occur on the portion of the upper surface overlying the region of material flow in the workpiece body. Surface displacement does not occur beyond this critical region. In view of the fact that the flow occurs at a 45 angle, the surface extent of the critical region will be equal to the thickness of the material.

After a suitable distribution of accommodating voids have been formed as hereinabove described, the material is ready to accept the figures to be hobbed, illustratively, the letters "John Doe." Referring to FIG. 4, conventional letter forms 26 spelling out the name John Doe" are held by the press device 22 in fixed relation in any suitable manner. As can be seen, the letters are arranged as they would appear in the final product.

As illustrated in FIG. 6, during the hobbing step the press is closed with sufficient force to impress the letter forms into the knurled surface of workpiece 20 to the desired depth, thereby forming a negative or mirrorimage imprint of the name as shown in FIG. 7. The depth of the imprint is equal to the desired height of the raised lettering to be cast.

It should be observed from FIGS. 7 and 8 that the surface voids nearest the imprinted letters are smaller in size than the voids further away from the letters. During the hobbing step, material in the area occupied by the letters becomes displaced and, in accordance with the invention, is accepted by the openings or voids in the knurled surface. As a result, distortion of the lettering is avoided.

After the press device 22 is opened, the workpiece 20 having the mirror-imaged letters imprinted thereon as in FIG. 8 is placed into a suitable die-casting apparatus 27 where the finished plaque or plate illustrated in FIG. 11 is formed. As illustrated in FIG. 11, the lettering constitutes an exact undistorted replica of the name John Doe as in the letter forms illustrated in FIG. 4. As can clearly be seen, the surface of the finished plaque of FIG. 11 also has formed thereon a distribution of raised surface areas 28 corresponding to the surface voids 25 in the workpiece 20.

It is to be understood that the present invention is not limited to knurling as a means for forming suitable voids in the workpiece material. Any other technique providing for the formation of voids in the body of the material or on its surface within the critical area illustrated in FIG. 10 is contemplated by the present invention. Similarly, it is to be understood that the invention is not limited to lettering but can be used to produce any type or arrangement of raised figures. The present invention has particular utility and represents a major advance in connection with lettering or numbering where standard printers forms can be employed.

1 claim:

1. A method of producing a mirror-image imprint of figures in a metal non-sheet material to serve as a master for the casting of raised figures such as lettering found on plaques and plates, which method comprises:

a. forming a plurality of voids in said non-sheet material without removing material in the surface which is to receive said imprint, said voids being suitable to accommodate the flow of material to be displaced during the imprinting of said figures and being located both within and without the areas to be occuppied by said imprinted figures;

b. arranging and securing forms of the figures to be cast in fixed relation coresponding to the raised figures to be produced by casting; and

c. impressing said forms into said material thereby causing that material in the areas occuppied by said forms to be displaced and causing a flow ofmaterial into a plurality 'of said voids to occur to produce an undistorted imprint constituting an exact mirror-image replica of the figures to be cast, said plurality of voids which receive said material including voids located outside the areas occuppied by said figures.

2. The method of claim 1 which comprises forming said voids in the surface of said material in which said imprint is to be formed by forming discontinuous depressions in said surface while simultaneously permitting the areas of said surface adjacent said depressions to be upwardly displaced thereby incrementally increasing the thickness of said material without removing material from said surface.

3. The method of claim 1 which further comprises forming the voids located in the region which includes the area to be occupied by said imprint and a peripheral region extending outwardly therefrom a distance equal to the thickness of said material so that said voids have a volume at least equal to the volume of the imprint to be formed.

4. The method of claim 3 which comprises forming said voids with a volume at least twice as great as the volume of said imprint to be formed.

5. A method of making a master for the die casting of raised figures such as lettering found on plaques and plates, which method comprises forming a mirrorimage impression of said figures by hobbing forms of said figures into the surface of a metal non-sheet material, said material having pre-formed therein without removal of material from the surface to receive said impression a distribution of voids located both within and without the areas to be occupied by said figures, and causing substantially all of the material displaced by the hobbing of said figures to flow into said voids including some voids located outside the areas occupied by said impression of said figures thereby avoiding distortion of said impression.

6. The method of claim 5 which comprises hobbing said figures into said material having said voids on the 7. The method of claim 6 which comprises hobbing said figures into said material having said voids located in the region including the areas to be occupied by said impression and a peripheral region extending outwardly therefrom a distance equal to the thickness of said material.

8. A method of producing a mirror-image imprint of figures in a metal non-sheet material to serve as a master for the casting of raised figures such as lettering found on plaques and plates, which method comprises: (a) taking a metal non-sheet material having a plurality of voids formed therein without material having been removed during the formation of said voids from the surface to receive said imprint, said voids being suitable to accommodate the flow of material to be displaced during the imprinting of said figures and being located both within and without the areas to be occuppied by said imprinted figures; (b) arranging and securing forms of the figures to be cast in fixed relation corresponding to the raised figures to be produced by casting; and (c) impressing said forms into said material thereby causing that material in the areas occuppied by said forms to be displaced and causing a flow of material into a plurality of said voids to occur to produce an undistorted imprint constituting an exact mirror-image replica of the figures to be cast, said plurality of voids which received said material including voids located outside the areas occuppied by said figures.

* t i i

Claims (8)

1. A method of producing a mirror-image imprint of figures in a metal non-sheet material to serve as a master for the casting of raised figures such as lettering found on plaques and plates, which method comprises: a. forming a plurality of voids in said non-sheet material without removing material in the surface which is to receive said imprint, said voids being suitable to accommodate the flow of material to be displaced during the imprinting of said figures and being located both within and without the areas to be occuppied by said imprinted figures; b. arranging and securing forms of the figures to be cast in fixed relation coresponding to the raised figures to be produced by casting; and c. impressing said forms into said material thereby causing that material in the areas occuppied by said forms to be displaced and causing a flow of material into a plurality of said voids to occur to produce an undistorted imprint constituting an exact mirror-image replica of the figures to be cast, said plurality of voids which receive said material including voids located outside the areas occuppied by said figures.

2. The method of claim 1 which comprises forming said voids in the surface of said material in which said imprint is to be formed by forming discontinuous depressions in said surface while simultaneously permitting the areas of said surface adjacent said depressions to be upwardly displaced thereby incrementally increasing the thickness of said material without removing material from said surface.

3. The method of claim 1 which further comprises forming the voids located in the region which includes the area to be occupied by said imprint and a peripheral region extending outwardly therefrom a distance equal to the thickness of said material so that said voids have a volume at least equal to the volume of the imprint to be formed.

4. The method of claim 3 which comprises forming said voids with a volume at least twice as great as the volume of said imprint to be formed.

5. A method of making a master for the die casting of raised figures such as lettering found on plaques and plates, which method comprises forming a mirror-image impression of said figures by hobbing forms of said figures into the surface of a metal non-sheet material, said material having pre-formed therein without removal of material from the surface to receive said impression a distribution of voids located both within and without the areas to be occupied by said figures, and causing substantially all of the material displaced by the hobbing of said figures to flow into said voids including some voids located outside the areas occupied by said impression of said figures thereby avoiding distortion of said impression.

6. The method of claim 5 which comprises hobbing said figures into said material having said voids on the surface which is to receive said mirror-image impression.

7. The method of claim 6 which comprises hobbing said figures into said material having said voids located in the region including the areas to bE occupied by said impression and a peripheral region extending outwardly therefrom a distance equal to the thickness of said material.

8. A method of producing a mirror-image imprint of figures in a metal non-sheet material to serve as a master for the casting of raised figures such as lettering found on plaques and plates, which method comprises: (a) taking a metal non-sheet material having a plurality of voids formed therein without material having been removed during the formation of said voids from the surface to receive said imprint, said voids being suitable to accommodate the flow of material to be displaced during the imprinting of said figures and being located both within and without the areas to be occuppied by said imprinted figures; (b) arranging and securing forms of the figures to be cast in fixed relation corresponding to the raised figures to be produced by casting; and (c) impressing said forms into said material thereby causing that material in the areas occuppied by said forms to be displaced and causing a flow of material into a plurality of said voids to occur to produce an undistorted imprint constituting an exact mirror-image replica of the figures to be cast, said plurality of voids which received said material including voids located outside the areas occuppied by said figures.

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