US2349920A - Die - Google Patents

Description

May 30, 1944. Q J, WELCOME 2,349,920

DIE

Original Filed Aug. 19', 1940 C'r! J. Welcome.

Patented May 30, 1944 i @.g;

N UNITED STATES rATENT OFFICE DIE 'Carl'.ll Welcome, Toledo, Ohio original application August 19, 1940, serial No. 353,195. Divided and this application August 25,1941, serial No. 408,182 f 3 claims., (ci. iii- 47) My invention relates `tothe-art of duplicating Aobjects vand particularly to the fabrication of molds, tools and `dies for accurately reproducing objects irrespective lof intricacy of design or form, and is a division of my copending application, Serial No. 353,l95,filed August 19, 1940.

The invention comprehends simple, inexpensive dies, tools and molds for duplicating objects to exact form and dimensions, eliminating tedius and time consuming operations which require a, 10

high degree of skill.

The invention includes the provision of a die or cavity molcl formed of an exceedingly hard metal which Will withstand heat, abrasion and corrosion and which can be readilyand inexpensivelyy 1# -reconditioned without the necessity of complicated machine operations.

It is an object of my invention to provide improvements in the manufacture of mold's,tools and dies which makes very easy and rapid pro-1 20 or dies having a low coeflicient of expansion 'ari'daq which are more rsistant to heat,"abra`sio`nand most chemical reactions, than arev dies now made of 'tool steel or alloy steel.

' It is an object of my invention tofacdomplish nien which Will be an accurate replica ofv the model by electrodepositing metallic layers on the surface of the model. It is an object of my invention to produce a die formed of superimposed'metals vs /herein the `face metal exposed to vvvearis bonded to an underlying or foundation r'netal,l the latter "being capable `of withstandingwithout deterioration the removal of the facefmetal. f 4 l It is an object of my invention ,toproducea ,die by depositing on a `f undatio'n layer or metallic structure, having the shape of the Working surface of the die, a hard metal to` form a lbacking which also takes `the shape of the workingfno.

surface of the die. y Y,

l It is an objectof my invention to make molds, tools, and dies by workmenpf Yo itliiiar'y skill Iin `a shorter time than has heretofore been retion of hobbing out, and hand tooling which is necessary at the present time.

It is an object of my invention to make molds and dies of metallic layers which are deposited electrically or otherwise upon the surface of the object to be duplicated including: a hard metal capable of Abeing stripped and reconditioned vforming the face or working surface; a softer metal preferably of the base metal type capable of withstanding the removal or stripping operation of the face metal Without deterioration constituting the foundation metal or metallic shell having the shape of the working surface; a primary base substantially of the same metal as that face, having toughness, hardness, heat resistance and shock resistance; and a secondary base of malleable or softer metal which can be applied mechanically and shaped to conform to vthe press or machine used for operating the die.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structure, to various details of yconstruction and to combination-s of` parts, elements per se, and to economies of manufacture and numerous other features as will be apparent `from a consideration of the specification and drawing ,of a form of the invention, which may vlie-preferred, in which:

Figurer 1 isa side elevational view with a portion in section of a pattern or article to be duplicatedin accordance with the method of my invention; 1

Figure 2 is a sectional view illustrating the die thmakmg of tools and dies by hsk-medwokwg; Ablock produced in accordance with my improved Figure 2;

Figure 4 is a cross sectional view of the article to be duplicated, illustrating that a portion of the surface to be duplicated is coated with a current yconductive substance.

, Figure 5 represents the step of my improved methodin establishing the surface to be duplicated as a cathode in an electro-plating bath;

Figure 6 is a cross-section of the article illustrating the built up foundation shell produced by an electro-plating bath;

l Figure 7 represents the step of my improved method in establishing the deposited shell as a cathode in an ,electro-plating bath for depositing a reinforcing backing or primary base therequired, elminatingthslowand laborious opera- .-55 Y .Figure `8 illustrates the backed electro-plated The principles of the invention are illustrated in their practical application to the fabrication of a composite die block used for duplicating an article by utilizing a synthetic plastic material. However, the invention is not limited to this particular application but the-same comprehends the tact with the article is established as a cathode in an electro-plating chromium bath so that a film of a predetermined thickness is deposited on the copper shell to constitute the face or wearing surface of the die. This chromium lm should be of substantially the same over-all thickness of the coatin-gs employed to treat the article and establishing the selected surface as a cathode in the copper electro-plating bath. The resulting composite metallic structure is bonded or Y fixed to a suitable metallic support or secondary base applied to the primary base or chromium backing. I have found that the application of employment of the principles hereinafter enu-l g merated for producing tools for reproducing surface contours or articles utilizing metals or other upon a foundation metallic shell or upon a pri mary reinforcing metallic base. The foundation shell is formed or made of a metal somewhat more ductile having a different color characteristie than that of the face metal and capable of withstanding without impairment the removal of the face metal. The foundation-shell is preferably produced by the deposition of a suitable metal upon the surface'to be duplicated to take the shape of the same. This foundation shell is bonded to or reinforced by a metallic primary base suitably applied thereto;r the surface of the primary base taking also the shape or contour of the surface to be duplicated.' The primary base is carried by a suitable support made of a malleable metal, I

I have found out after considerable research and experimentation that a die or mold can be produced in a highly efficient and inexpensive manner by employing the followingsteps. The article or contourto be duplicated is preferably made or rendered capable of receiving without impairment a metallic deposition, the same is then established as a cathode in an electro-plating bathso that a metallic shell of the foundation metal is built up having the corresponding configuration. I have yfound that base type metals that canrbe electrically deposited without great cost such as copper, nickel or cobalt serve the purpose very effectively as foundation metals for building up the metallic shell as any one of these metals has the characteristics desired with referl 'ence to ductility, degree of hardness and capability of withstanding without impairment cer- Vtain physical or chemical actions to which the kthe secondary base can be effectively carried out before separating the article from the copper shell and that the deposition of the die face or `chromium lm can be very effectively accom plished after the `secondary base has been applied. In addition it is contemplated within the spirit of the invention to remove or dissolve the foundation metal by suitable agents such as by the application of nitric acid and apply to the primary base or chromium backing the hard face metaL building up the same to the thickness not only of coatings employed to treat the article and establish the selected surface as a cathode, -but also to the thickness of the layer of the foundation metal, so that the forming tool or die will comprise the hard face metal or workingsurface and the reinforcing bases or hackings.

Referring to the drawing which illustrates a practicalappHcation of the invention for producing as a forming tool a die element in which like reference characters are employed to designate like parts; in Figure 1 is shown a pattern or an article to be duplicated which is in the form of a paper weight I0 constructed to the actual contour and dimensions desired to be present inthe replicas or facsimiles produced by using4 the composite cavity die formed by the separable elements I2 and i4, a cross-section of which is illustrated in Figures 2, 3 and 10.

In carrying out my invention for duplicating articles, the surface or contour to be duplicated, whichv may be of metal, wood, plastic material. wax or other suitable material, is first cleaned with asuitable cleaner or solvent. If the surface of the article is of a material unsuitable to receive a metallic coating, its surface is treated to receive a metallic coating without impairment or is preferably rendered impervious to an electro-plating bath by applying any suitable acid repellent substance as, for example, beeswax which is distributed so as to produce a uniform lm or coating thereon. The particular portion of the surface of the treated article selected to constitute or form one of the elements of the die block, such as the lower element I4, is arranged to receive a metallic shell such as by covering the Asame with current conductive coating for receiving by electro-plating a metallic deposition thereon. I have found that a conductive coating produced by applying a solution containing graphite in suspension or any other suitable conductor, such as plumbago or aluminum paint is Vvery effective. In the embodiment illustrated particularly'shown in Figure 4, the base surface |'6 of the paper weight l0 which will constitute the lower die section i4 is coated as at i1 with a solution containing graphite so as to give a film of uniform thickness. The uniformity and the thicknessof the conductive coating Il are carefully controlled in order to secure a high degree of accuracy in the duplication of the ex- 'act dimensions .and 'contour of the base I6 of the article I0.'

The article I witnfits conductive coating I1 is then placed or immersed in an electro-plating bath Ill and established asa cathode so that a layer of copper, nickel, cobalt or other suitable 'material is deposited on Athe outer surface of the I and a spec-inc gravity density to produce a fine grained, ductile, smooth plate 'or initial electrical deposition and capable of being modified lor controlled so that during the building up of the shell, uneven ror irregular portions may bel formed at the back or rear of thelinitial deposition or surface layer, as particularly `'shown in Figures 5 and '6. I have found that a shell or plateproduced by van `electro-deposition of a base type metal such as copper serves the purpose very effectively, not only due to their low cost but because they perform the function of readily indicating the wearing of the die during use and also allow the reconditioning of the die, permitting changes when desired without tedious and time consuming operations which render metals of this type very adaptable forV the formation of a or foundation shell 20 is bonded to a metallic or 0 primary base by preferably immersing the treated article with its foundation metal 2l) in a chromium depositing bath, as shown in Figure '7, land the exposed surfaceor rear face of the metallic shell 20 is established as a cathode for the electrodeposition thereon ol"l chromium layer 22. The layer of chrome is builtup to the desired thickness by allowing the article with its metallic shell 2li to remain in the bath for a predetermined period of time, rapidity of the deposition may be regulated and accomplished by changing the temperature concentration of the bath and current density.`

The pattern il) `with its deposited electroplated coatings 2t and 22 is then removed from the chromium hath I9 and rinsed preferably in hot and cold Water or' other suitableage'nt to remove objectionable orl loose matter'.

The article Il) is then preferably separated from the metallic structurev 23 formed by the metallic coatings 20 and 22 by any suitable means. I have found that by subjecting the article III or metallic structure 23 to heat, due to the difference of expansion between the bonded metal coatings 2Q and 22 and the article Hl. -a very rapid and ef.. fective separation can be secured. This separation produces a composite metallic structure formed by the electro-plated coatings 20 and 22 having a front surface corresponding in contour to that of the base'IE of article Il] as is particularly shown in Figure 8.

The surface or face 25 of the metallic shell 2li, which has been in contact with the base I5 of the pattern or article to be duplicated, is cleaned with a suitable solvent or degreasing agent to remove any possible traces of the current conductive substance or graphite coating I1 formerly applied to the surface of the article. The metallic structure 23 is thereafter placed in a chromic acid bath 2l preferably having the particular constituents and incorporating the features set forth in United States Patent No. 1,881,885 of October ll, 1932, and the `front face 25 is established as a cathode for the deposition of a chrome film of fine quality deposited at a high current density and temperature. The metallic structure is allowed to rem-ain in the bath until a layer `2li of the very fine metallic chromium of predetermined thickness is deposited on surface 25. the layerv 28` having a thickness equal to the thickness` of the material covering the surface of the article to be duplicated such as that produced by the coating applied in treating the article and that of the conductive coating, so that the die will have the exact form and accurate dimensions of the model. The composite metallic structure formed by the chromium depositions 22 and 23 covering the soft metallic shell 2U of such metals as copper, nicke1 or cobalt is removed from the chromium bath and preferably polished to the desired gloss and smoothness after cleaning the same or removing any foreign matter therefrom. The rear surface 30 of the chromium layer 22 is bonded or secured to a suitable support or secondary backing 32 which may have the shape and configuration illustrated in Figure` 10 so as to be used as the lower element I 4 of the die block. The secondary backing is preferably made of a metalsecured by electro-deposition to the rear face 30 of thechromium plate 22, the metal being preferably of malleable character 4soit'hat machine operations can be performed with` ease and speed in order to give the shape and dimensions necessary to conform themachine or press used for` producing the facsimiles or replicas. I contemplate the employment of the Goldschmidt process described in United States Patent No.

`578,868 or by aluminothermic welding method for 5 bonding the secondary backing tothe surfaceS of the multi-layer metallic structure. However, this secondary backing can be produced by setting or solidifying molten metal around the metallic structure or by increasing the thickness of the metallic chro'mic deposition 22 to the desired size.

In the practical application of the invention for producing the lower die element I4, the steps and operations have been described as being performed in a `certain predetermined order. However effective results can be secured by changing their sequence. I have found that in the production of stamping dies or molds having complicated contours or intricate designs, it is very advantageous to apply the secondary backing or base 32 while the composite metallic structure 23 is in contacting engagement with the base I6 of the article Ill and that the step in separating the metallic structure from the article can be carried out after the secondary backing has been bonded or applied thereto. This procedure climi'nates any possible distortion of the metallic structure 23 when the secondary base is applied by casting or adding a molten metal thereto which is in some cases very desirable. In addition, this procedure provides means for readily ascertaining any distortion which may have taken place by observing any marks in the outer surface of the article. Moreover, by applying the hard chromium lm 28 as a last step in the process, any irregularities or distortion present in theV metallic structure 23 can .be compensated for either by changing'the contour of the face 25 of vthel malleable layer or'foundation shell 28 or ing a visual indication which readily apprises Vthe I operator of any Wearing'of the working surface of the die. This indication is very noticeable when the working surface of the die is of chromium and the underlying metal employed is copper, as the latter gives a yellowish cast to the area subject to undue wear before the surface 25 of the copper shell is impaired. The foregoingfeature is very desirable because it informs vthe operator that the die is due for reconditioning before appreciable changes in dimensions and contour have taken place which in many cases destroy the dies usefulness causing its immediate lobsolescence as in present practice undue Wear of thev working areas prevents the possible reconditioning of a die. ing metal which, as hereinbefore pointed out, is capable of withstanding the application of physical or chemicalagents for the removal of the chromium facing without impairment allows that the die could' be re-established to its original di-' mensions and used again by only applying a chromium coating having a predetermined thickness.

The reconditioning of the die when wear of its face metal has taken place can be accomplished Y very effectively by stripping or removing the hard face metal or chromium lm 28 by any suitable means such as by the application of hydrochloric or muriatic acid which Will remove the chromium.' Afrom the foundation metal or copper shell 2D so that the surface 25 will be clear of any chromium layer. After the surface 25 of the foundation metal 20 is free from impurities the same Moreover, the underlyis established as a cathode for the electro-depo-f.:

sition thereon of a new hard chromium film or face layer'. The chromium lm should have the same thickness as the layer 28 originally applied to the copper shell 28. i

i 1 contemplate within the spint `of the inve'n-g,

Y tion to produce a die, mold or forming tool which will comprise the hard face metal or ne chromium lm 28 bonded tothe primary base v22 or vto a reinforcing or supporting base structure 32.

This type of die can be accomplished by follow-,

ing the steps contemplated to produce the foundation shell 20 and its reinforcing backings prior to the application of the face metal 28, by dissolving or removing the copper shell 20 by the application of nitric acid thereto and thereafter,-

electro-depositing upon the primary base or chromium backing 22 the hard face metal layer 28 building up the chromium deposition to a thickness corresponding to the coatings applied to treat the article and establishing selected surface as a cathode as Well as the thickness of the foundation metal 20 so that the die will have the exact form and accurate dimensions of the model.

It is also contemplated within the spirit of the invention that in cases wherein the model or contour to be duplicated is made of a base type metal such as copper, nickel or cobalt, the foundation metal or copper shell 20 and the steps contemplated to produce the same can be dispensed with and a die can be produced by electro-depositing on the selected metallic surface of the model a chromium film of ne quality which will form the face 28 or the wearing surface of the die and thereafter applying suitable reinforcing or supporting bases such as 22 and 32. I contemplate the removal of the article from the chromium face 28 of the die proper by dissolving the article through the use of a suitable chemical agent such as by applying a nitric acid thereto so that the forming tool or die will comprise a chromium layer or lm 28 of fine quality constituting the working surface of the die and suitable reinforcing bases or supporting structures bonded thereto.

In the practical application of the invention the method has been described with reference to the production of the lower section I4 of the die block, but it is contemplated thatl the upper element I2 can be produced by following the steps hereinbefore enumerated. In such case, the upper surface of the paper weight I5 is arranged in lieu of the base I6 to receive the metallic depositions to produce a composite metallic structure having the shape and configuration of the die element I2 of the die block.

It is apparent that, withinthe scope of the invention, modifications @d different arrangements may be made other than is herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

What I claim is:

1. A die including a foundation metal having a die surface face a layer of chromium of substantially uniform thickness covering the face of said foundation metal; the foundation metal having a different color and degree of hardness than that of said layer, and its face formed to the shape of the working surface of the die; and a chromium backing deposited on the back of said foundation metal.

2. A die including a layer of chromium of substantially uniform thickness constituting the working surface of the die and being bonded to a cobalt supporting shell; the supporting shell formed t0 the shape of the working surface of the die made by electrolytic deposit; and a chrorrliun backing bonded on the rear surface of said s e 3. A die formed of superimposed metals including a layer of chromium of substantially uniform thickness constituting the working surface of the die; a metallic foundation of nickel bonded to said chromium layer the face of the metallic foundation formed to the shape of the working surface of the die; a layer of chromium bonded to the rear surface of said metallic foundation forming a covering therefor; and a metallic backing bonded to said chromium covering.

CARL J. WELCOME.

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