US3655309A

US3655309A - Rotating fixture-mold for fabricating printing drums

Info

Publication number: US3655309A
Application number: US806829A
Authority: US
Inventors: Neal Hepner
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1967-11-15
Filing date: 1969-03-13
Publication date: 1972-04-11
Anticipated expiration: 1989-04-11

Abstract

A rotating fixture-mold for locating and holding type bearing print members in a spatical relationship to each other and to the axis of rotation of the fixture mold. The type bearing print members when molded together form a drum structure which may be used as a printing drum or as an intermediate mold.

Description

United States Patent Hepner [4 Apr. 11, 1972 [54] ROTATING FIXTURE-MOLD FOR F ABRICATING PRINTING DRUMS f r n es Ci ed [72] Inventor: Neal Hepner, Birmingham, Mich. UNITED STATES PATENTS [73] Assignee: Burroughs Corporation, Detroit, Mich. 2,023,040 12/1935 Adam, Jr. 164/298 X 3,214,506 10 1965 Corbin, Jr ....l8/26 R UX 1 Flledr 13, 1969 3,505,437 4/1970 Eichmann et a1 ..l8/26 RR 21 A l. N 806 829 1 pp 0 Primary Examiner-J. Spencer Overholser Related us. A li ati Data Assistant Examiner-David S. Safran Attorne Paul W. Fish and Edwin W. Uren [62] Division of Ser. No. 690,041, Nov. 15, 1967, Pat. No. y

3,529,054. 57 ABSTRACT [52] U S Cl 425/109 425/120 425/123 A rotating fixture-mold for locating and holding type bearing 425/435 print members in a spatical relationship to each other and to the axis of rotation of the fixture mold. The type bearing print 3 members when molded together form a drum structure which 18/DIG. 10; 264/261, 275, 596, 241, 245, 260;

may be used as a printing drum or as an intermediate mold.

9 Claims, 18 Drawing Figures PATENTEDAPR 11 I972 3,655,309

SHEET 1 OF 3 IN Vlz'N'IUR.

NEAL HEPNER.

A T TORNEY PATENTEBAPR 11 I972 3,655,309

sum 3 BF 3 ooo ROTATING FIXTURE-MOLD FOR FABRICATING PRINTING DRUMS This is a division of application Ser. No. 690,041 filed Nov. 15, 1967 US. Pat. No. 3,529,054 issued Sept. 15, 1970 entitled Method for Fabricating Printing Drums which is assigned to the same assignee.

FIELD OF THE INVENTION This invention relates generally to an apparatus for use in fabricating structures of various geometric shapes having an axis of rotation such as printing drums and wheels.

SUMMARY OF THE INVENTION A rotatable fixture mold having a cylindrical cavity along its axis of rotation. The ends of the cavity are defined by a pair of detachable end plates. The volume enclosed by the cylindrical wall of the cavity and the inside faces of the end plates define a fixture chamber into which a plurality of type bearing print members are placed. The type bearing print members are located by a plurality of projections placed on at least one surface within the cavity. Adjacent to one end plate and coupled thereto is an inlet chamber for receiving a moldable material which is to be placed within the fixture chamber. In order to transfer the moldable material from the inlet chamber to the fixture chamber there is at least one port extending through one end plate through which the molding material can transfer.

IN THE DRAWINGS FIG. 1 is a perspective view of apparatus which may be employed to rotate the fixture-mold;

FIG. 2 is an end view of the fixture-mold partly broken away and in section;

FIG. 3 is a sectional view, taken along the line 3-3 of FIG.

FIG. 4 is a perspective view of a drum rim structure fabricated with the use of the fixture-mold of FIGS. 2 and 3 and the apparatus of FIG. 1;

FIG. 5 is a perspective view of another fixture-mold to receive the rim structure of FIG. 4;

FIG. 6 is a perspective view of the finished printing drum;

FIGS. 7 to 11 are fragmentary sectional views, illustrating the steps of a method utilizing the fixture-mold;

FIG. 12 is an exploded perspective view of a fixture-mold of another embodiment;

FIG. 13 is a perspective view of a drum rim structure fabricated with the use of the fixture-mold of FIG. 12;

FIG. 14 is a perspective view of another fixture-mold to receive the rim structure of FIG. 13;

FIG. 15 is a perspective view of the completed printing drum;

FIGS. 16 and 17 are fragmentary sectional views illustrating certain steps of a method utilizing the fixture-mold of FIG. 12; and

FIG. 18 is a perspective view of a rim structure element of the drum rim structure of FIG. 5.

DETAILED DESCRIPTION Referring to the drawings by characters of reference, and in particular to FIGS. 2, 3, 4, and 18, there is illustrated a fixturemold 101 for use in fabricating a plurality of rim segments 103 into a drum rim structure 100. The mold 101 is of sectional construction comprising a sleeve 105, defining a cylindrical wall, closure walls comprising a first end plate 107, and a second end plate 109, and an end cap 113. The several sections of the mold 101 are fastened together by any suitable means such as screws and bolts which are shown in FIG. 3. The two axially

opposed end plates

107 and 109 and the sleeve 105, when fastened together, define an annular molding chamber surrounding a cylindrical fixture chamber or cavity, into which the rim segments 103 are placed and held. Each rim segment 103 has an elongated web 102 to which a rim forming head or flange 104 is attached. As is illustrated in FIG. 18, along the broad surface of the head 104 there is securely located in a row a plurality of type faces or characters 106.

In the cylindrical fixture cavity, the rim segments 103 are located and held between a plurality of spacers 115 which are integral with and on the inner surface of the first end plate 107 and a plurality of axially opposed spacers 119 which are integral with and on the inner surface of the second end plate 109. Both sets of

spacers

115 and 119 are equally spaced in an angular relationship about the center of the

plates

107 and 109. The circumferential distance between adjacent spacers is slightly larger than the thickness of the web 102 of the rim segment. Therefore, each segment is held by adjacent spacers so as to permit movement within the fixture in the radial direction only. The axial distance between the

spacers

115 and 119 and the inner wall 114 of the sleeve or the annular molding chamber defines the radial thickness of the drum rim cavity and is slightly greater than the thickness of the head 104 of the rim segment 103.

In the second end plate 109, there is also a plurality of ports or apertures 111 equally spaced in an angular relationship about the center of the plate 109. With respect to the spacers 119, the apertures 111 are located adjacent to each spacer and on the inside of each spacer. It is through these apertures 111 that the molding material 127 enters into the cylindrical fixture cavity.

The end cap 113 provides an inlet cavity 123 to the mold 101. The cavity is conical in shape extending from the inlet 121 to the surface of the second end plate 109. The major diameter or flared end of the inlet cavity 123 is equal to or greater than the diametric distance spanning two apertures 111; thereby each aperture 111 is wholly within the conical cavity.

With the second end plate 109 and the end cap 113 removed, the rim segments 103 are loaded into the fixture cavity by slideably inserting a web 102 between each spacer 115. The head portion 104 is positioned between the spacer and the inner wall 114 of the sleeve in the molding chamber. The second end plate 109 is then positioned over the opposite end of the rim segment 103 thereby securely holding each segment 103. The end cap 113 is then placed over the end plate forming the completed fixture-mold. This is illustrated in FIG. 7.

The mold 101 is rotated about its axis which may be accomplished by coupling the mold to the axis of a motor as is illustrated in FIG. 1. When the mold is rotating, the centrifugal force which is generated, causes the rim segments 103 to move in a radially outward direction so that the type faces 106 are in an abutting relationship with the inner wall or surface 114 of the sleeve. This is illustrated in FIG. 8.

During rotation, a predetermined amount of molding material 127 is introduced into the molding chamber through the inlet' 121. The tapered sides of the inlet chamber 123 direct the material toward the apertures 111. The material is placed in rotation in the chamber, and when the material reaches the apertures, it enters therethrough into the annular molding cavity under rotation and does not splash against the rim segments 103. With the apertures so positioned, the material is directed into the annular cavity without touching the segments 103 in the area where the material is not to be molded. The reason for avoiding any contact other than that desired, is to prevent contamination which may be detrimental to any subsequent operations. The radial thickness of the rim depends upon the amount of material 127 which is introduced into the inlet 121. This is illustrated in FIG. 9.

The purpose of the molding material in such a drum rim structure 100 as shown for example, in FIG. 4, is to provide a temporary holding fixture which holds the rim segments 103 together unaided and which also seals the encapsulated flange 104 of the rim segments during a subsequent molding operation. Since the structure 100 is used as a temporary holding fixture, one of the fusible alloys such as Cerrolow 117, an alloy comprising Bismuth 44.7 percent, Lead 22.6 percent, Tin 8.3 percent, Cadmium 5.3 percent and Indium 19.1 percent, as marketed by Cerro de Pasco Sales Corporation can be used. Other materials could also have been used such as rubber, plaster, resin epoxy, phenolic, etc., depending upon the ultimate use of the drum rim structure 100.

After the molding material has hardened, the mold 101 is disassembled and the unitary drum rim structure 100 is removed from within the sleeve 105. Next the drum rim structure is placed within a second mold, as illustrated in FIG. 5 to complete the fabrication of a printing drum 129, illustrated in FIG. 6.

The second mold, as shown in F IG. 5, comprises a pair of

end caps

133 and 135 which are placed over each end of the rim structure 100. Both caps 133 and 135 have a coaxial aperture 139 to locate and support a mounting shaft 131. Also, the top end cap 133 has a plurality of openings 141 therein to allow a permanent molding compound to be poured into the inner chamber of the rim structure. The bottom end cap has no other openings other than the shaft location aperture. Both caps 133 and 135 are coupled together through a series of bolts 137 placed outwardly of the structure 100.

After the second mold is assembled, a permanent molding material 143 is poured into the chamber. By way of illustration in the fabrication of the printing drum 129, the molding material 143 comprised: 28 parts by weight of Shell Epon Resin 815, an epichlorohydrin/ bisphenol A-type epoxy resin having an average molecular weight of approximately 330 and an equivalent weight of about 185 as marketed by Shell Chemical Co, 12 parts by weight of Genamid 250, a fatty amidoamine resin having an amine value of approximately 425, as marketed by General Mills, Co., which is the hardener, and 60 parts by weight of Reynolds Aluminum No. 200 a filler comprising 98 percent pure Aluminum powder and 2 percent impurities. This mixture provides a strong bond between the rim segments 103 and the shaft 131 and with the aluminum filler, the shrinkage is reduced to an acceptable amount. This is illustrated in FIG. 10.

After the molding mixture 143 has cured the end caps 133 and 135 are removed and the dissolvable molding material 127 is removed from the periphery of the drum and the drum is complete as illustrated in FIG. 6.

Referring to FIGS. 12 through 17, there is shown and illustrated a fixture-mold of another embodiment. The fixturemold 155, shown in FIG. 12, is used to locate and hold a plurality of discs 149 in a predetermined spaced relationship for fabricating into a drum-like structure 169, which is shown in FIG. 13. The discs 149 have a plurality of type faces or characters 150 spaced around the periphery thereof.

The fixture-mold 155 is of sectional construction comprising a first end plate or closure wall 163, a

sectional sleeve

159 and 161 which together form a cylindrical wall, a second end plate 165 or closure wall and an end cap 167. The several sections of the mold 155 are fastened together by any suitable means such as screws and bolts. The two

end plates

163 and 165 and the

sectional sleeve

159 and 161 when fastened together, form a cylindrical fixture cavity or chamber and an annular molding cavity or chamber within the fixture into which the several discs 149 are placed and held.

In the cylindrical fixture cavity, each disc is located and held by three

projections

174, 175, and 176 which extend from the inner walls 171 and 173 of the sleeve sections. These projections are angularly spaced apart about the axis of the cavity with one projection 174 located on the inner wall 173 of the sleeve section 161 at the apex of the section. The other two

projections

175 and 176 extend from the inner wall 171 of the other sleeve section 159. In the present embodiment, the

projections

174, 175, and 176 are basically shaped in the form of frustum of a cone with an impression of a type character formed in the outboard surface. The type face 150 on the disc 149 is located within the impression on each projection and securely held thereby. The axial distance between projections corresponds to the center to center distance A of adjacent type along a row of type. The length of the projections from the inner walls determines the amount of molding material 156 which will overlie and encapsulate the type faces 150.

With both end plates 163 and fastened to the sleeve section 159 which has two projections and 176 per disc, the desired number of discs are loaded by positioning the correct type face on each

projection

175 and 176 lying within a given circular plane of the cavity. After all the discs are loaded, the other sleeve section 161 is positioned over the discs and fastened between the two

end plates

163 and 165.

The second end plate 165 has a plurality of ports or apertures 181 equally spaced in an angular relationship about the center of the plate. The radial distance to the apertures 18] is such as to position them substantially above the type faces 150 of the discs 149. It is through these apertures that the molding material 156 enters into the annular molding cavity.

The end cap 167 provides an inlet cavity to the mold 155. The cavity is defined by an endless conical surface 177 extending from the inlet aperture 179 to the surface of the second end plate 165. The diameter of the cavity at the end plate or flared end of the cavity is equal to or greater than the diametn'c distance spanning two apertures 181; thereby each aperture is wholly within the conical inlet cavity. The end cap 167 is securely fastened over the second end plate 165 forming the completed fixture-mold 155 containing the discs therein.

The mold 155 is rotated about its axis which may be accomplished by coupling the mold to the axis of a motor or any similar rotating shaft.

During rotation, a predetermined amount of molding material 156 is introduced into the mold through the inlet 179. The tapered sides 177 of the inlet chamber direct the material toward the apertures 181. The material 156 is placed in rotation in the chamber and when the material reaches the apertures, it enters therethrough into the annular molding cavity under rotation and does not splash against the discs 149. With the apertures 181 so positioned, the material is directed into the annular cavity without touching the discs in the fixture chamber where the material is not to be molded. The reason for avoiding contact with surfaces that are not to be molded, is to prevent contamination which may be detrimental to any subsequent operations. The radial thickness 157 of the rim depends upon the amount of material 156 which is introduced into the inlet 179.

The purpose of the molding material 156 in such a drum structure 169, as shown for example in FIG. 13, is to provide a temporary holding fixture which holds the discs together unaided and which also seals the encapsulated type faces 150 of the discs during a subsequent molding operation. Since the structure 169 is used as a temporary holding fixture, one of the fusible alloys, such as Cerrolow 117, an alloy comprising Bismuth 44.7 percent, Lead 226 percent, Tin 8.3 percent, Cadmium 5.3 percent and Indium 19.1 percent, as marketed by Cerror de Pasco Sales Corporation can be used for the molding material. Other material could also have been used such as rubber, plaster, resin epoxy, phenolic, etc., depending upon the ultimate use of the drum structure 169.

After the molding material has hardened, the mold 155 is disassembled and the unitary drum structure 169 is removed. Next the drum structure is placed within a second mold, as illustrated in FIG. 14 to complete the fabrication of the printing drum 147 illustrated in FIG. 15.

The second mold, as shown in FIG. 14, comprises a pair of

end caps

182 and 183 which are placed over each end of the drum structure 169. Both caps 182 and 183 have a coaxial aperture 187 to locate and support a mounting shaft 151. Also, the top end cap 182 has a plurality of openings 189 therein to allow a permanent molding compound 191 to be poured into the inner chamber of the drum structure. The bottom end cap 183 has no other openings other than the shaft location aperture. Both caps are coupled together through a series of bolts placed outwardly of the drum structure 169.

After the second mold is assembled, a permanent molding material 191 is poured into the chamber. By way of illustration in the fabrication of the printing drum 147, the molding material 191 comprised: 28 parts by weight of Shell Epon Resin 815, an epichlorohydrin/ bisphenol A-type epoxy resin having an average molecular weight of approximately 330 and an equivalent weight of about 185, as marketed by Shell Chemical Co., 12 parts by weight of Genamid 250, a fatty amidoamine resin having an amine value of approximately 425, as marketed by General Mills, Co., which is the hardener, and 60 parts by weight of Reynolds Aluminum No. 200 a filler comprising 98 percent pure Aluminum powder and 2 percent impurities. This mixture provides a strong bond between the discs 149 and the shaft 151 and with the aluminum filler, the shrinkage is reduced to an acceptable amount. This is illustrated in Fig. 16.

After the molding mixture 191 has cured the end caps 182 and 183 are removed and the dissolvable molding material 156 is removed from the periphery of the drum and the drum is complete as is illustrated in FIG. 15.

lclaim:

l. A rotating fixture-mold for fabricating printing drums from a plurality of character-bearing print members comprismg:

a cylindrical wall open at each end,

closure walls closing each end of said cylindrical wall and cooperable therewith defining a fixture chamber,

locating members on at least one of said walls, said members projecting inwardly into said fixture chamber and concentric therewith providing means to locate and align the plurality of character bearing print members within said fixture chamber, and

a cap cooperating with one of said closure walls to define an inlet chamber, said one closure wall having a port therethrough to effect communication between said inlet chamber and said fixture chamber for the introduction of a moldable material into the fixture chamber.

2. The rotating fixture-mold according to claim 1 wherein the locating members are a plurality of angularly and axially spaced projections on the cylindrical wall.

3. The rotating fixture-mold according to claim 2 wherein the projections are in the form of a frustum of a cone extending inwardly from the cylindrical wall a predetermined distance.

4. The rotating fixture-mold according to claim 3 wherein the outboard surface of said projections has an impression of one of the type of the print members to receive the corresponding type on the print member for supporting the print memberthereby.

5. The rotating fixture-mold according to claim 1 wherein the locating members are a plurality of axially opposed spacers equally and angularly spaced on each of the closure walls for maintaining the print members parallel to the axis of rotation of the fixture-mold.

6. A rotatable fixture-mold for fabricating drum rims comprising a cylindrical sleeve, closure members closing the ends of said sleeve, elongated rim segments having a flanged portion thereon extending in the direction of length of said segments, spacers on the inner faces of said closure members for holding said rim segments in angular spaced apart relationship about the axis of said sleeve and said spacers cooperable with said flanged portions for defining a fixture chamber and a molding chamber surrounding the fixture chamber and a cap cooperating with one of said closure members defining an inlet chamber, said one closure member having ports therethrough adjacent to and inwardly of said spacers for effecting communication between said molding chamber and said inlet chamber for the introduction of a moldable material into the molding chamber.

7. A rotatable fixture-mold according to claim 6 wherein said rim segments have a T-shaped cross section extending in the direction of length of said segments and flanged cross bar of said cross section being a separating member between said fixture chamber and said surrounding molding chamber.

8. A rotatable fixture-mold according to clarm 6 wherein the other of said closure members has an aperture therein substantially the diameter of said fixture chamber for limiting the amount of moldable material in said molding chamber thereby limiting the thickness of the drum rim.

9. A rotatable fixture-mold for molding a plurality of rim segments into a drum rim structure, said fixture-mold comprising:

a cylindrical sleeve open at each end,

a first and second plate enclosing each end of said sleeve, each of said plates cooperating with the inner surface of said sleeve forming an annular molding chamber therein,

a plurality of axially opposed alignment members equally and angularly spaced on said plates extending inwardly of said annular molding chamber, said members for aligning and supporting the rim segments,

an inlet chamber adjacent to said first plate and having a flarred end substantially equal in dimension to said annular molding chamber for receiving and directing the molding material thereto, and

a plurality of equally and angular spaced apertures in said first plate interconnecting the flarred end of said inlet chamber with the annular molding chamber for transferring the molding material from said inlet chamber to said annular molding chamber.

Claims

1. A rotating fixture-mold for fabricating printing drums from a plurality of character-bearing print members comprising: a cylindrical wall open at each end, closure walls closing each end of said cylindrical wall and cooperable therewith defining a fixture chamber, locating members on at least one of said walls, said members projecting inwardly into said fixture chamber and concentric therewith providing means to locate and align the plurality of character bearing print members within said fixture chamber, and a cap cooperating with one of said closure walls to define an inlet chamber, said one closure wall having a port therethrough to effect communication between said inlet chamber and said fixture chamber for the introduction of a moldable material into the fixture chamber.

4. The rotating fixture-mold according to claim 3 wherein the outboard surface of said projections has an impression of one of the type of the print members to receive the corresponding type on the print member for supporting the print member thereby.

8. A rotatable fixture-mold according to claim 6 wherein the other of said closure members has an aperture therein substantially the diameter of said fixture chamber for limiting the amount of moldable material in said molding chamber thereby limiting the thickness of the drum rim.

9. A rotatable fixture-mold for molding a plurality of rim segments into a drum rim structure, said fixture-mold comprising: a cylindrical sleeve open at each end, a first and second plate enclosing each end of said sleeve, each of said plates cooperating with the inner surface of said sleeve forming an annular molding chamber therein, a plurality of axially opposed alignment members equally and angularly spaced on said plates extending inwardly of said annular molding chamber, said members for aligning and supporting the rim segments, an inlet chamber adjacent to said first plate and having a flarred end substantially equal in dimension to said annular molding chamber for receiving and directing the molding material thereto, and a plurality of equally and angular spaced apertures in said first plate interconnecting the flarred end of said inlet chamber with the annular molding chamber for transferring the molding material from said inlet chamber to said annular molding chamber.