US3542620A - Fabrication of a printer drum - Google Patents

Description

" Nov. 24, 197 0 F. ca. DEDEK FABRICATION OF A PRINTER DRUM Filed Nov. 15, 1967 INVENTOR.

A T TOR/VB Y.

FRANK e. DEDEK.

United States Patent Office 3,542,620 FABRICATION OF A PRINTER DRUM Frank G. Dedek, Westlantl, Mich., assignor to Burroughs Corporation, Detroit, Mich., a corporation of Michigan Filed Nov. 15, 1967, Ser. No. 683,188 Int. Cl. B32b 31/00 US. Cl. 156-293 1 Claim ABSTRACT OF THE DISCLOSURE A method of fabricating a printing drum comprising a shaft and a plurality of type-carrying discs axially mounted thereon. Each disc carries a plurality of type characters spaced around its periphery. Each disc is bonded to the shaft by a layer of bonding material, such as an epoxy, between the disc and the shaft. Each disc is further bonded by an adhesive film placed between adjacent discs. Both the bonding material and the adhesive film are then cured. Before curing, corresponding type characters on each disc are aligned to every other disc. Alignment is performed at the type characters to assure accuracy.

BACKGROUND OF THE INVENTION Field of invention The invention relates generally to printing drums particularly and to a method of fabricating a plurality of type discs and shaft into a printing drum unit.

Description of prior art At present, the method of fabricating printing drums includes the keying of a number of type carrying discs to a shaft. In fabricating the key and cutting the keyway for a printing drum, the cost is exorbitant because a high degree of accuracy in machining must be maintained if the type are to align. The angular location of a keyway in the center of a printing disc with the type character on the periphery of the disc is extremely difficult to maintain and result in frequent scraping of the parts. A tolerance of .0005 inch in the keyway location generally results in a character tolerance of from two to five times that amount, depending on the size of the disc.

SUMMARY OF THE INVENTION This invention resides in bonding together several typecarrying discs on a shaft which together comprise a printing drum. This method of fabricating a printing drum provides for accurate alignment of each type character in rows parallel to the shaft by aligning at the periphery of the disc instead of by key and keyway connections at the periphery of the shaft.

It is therefore, a principal object of this invention to eliminate keys and keyways for locating printing discs along a mounting shaft.

A further object of this invention to reduce the cost of fabricating printing drum assemblies by eliminating the need for close tolerances on the mounting surfaces of the several discs comprising a printing drum assembly.

DESCRIPTION OF FIGURES The invention will best be understood by reference to the following detailed description taken in connection with the accompanying drawings, in which:

FIG. 1 is a end view of a printing drum showing the type aligning bail in position;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1.

DETAILED DESCRIPTION Referring to the drawings by characters of reference, there is shown in FIG. 1 a printing drum unit comprising a shaft 11 and a plurality of centrally apertured type discs 13 positioned on the shaft. A pair of clamps 15 and 17 are indicated on either side of the type discs 13 holding the apparatus together. Also, there is shown one form of an aligning bail 19 for aligning the type of the discs 13 in rows, the bail being supported on the shaft as shown.

The clamps 15 and 17, shown in FIG. 2, are slideably mounted on shaft 11 and are secured by any suitable means, such as set screws 21 and 23. The purpose of the clamps is to hold the type discs together in a drum-like fashion until the fabricating process has been completed. Mounted to each clamp 15 and 17 are a pair of arms 25 and 27 which extend away from the shaft 11 to support the aligning bail 19. The outboard end 28 of the arm 25 is bifurcated to form a locating channel 31 for the aligning arm 19. The aligning arm 19 is rotatably mounted on the hinge pin 29 which is securely located in the arms 33 and 35. The depth A of the channel 31 is sufiicient to allow the aligning bail to freely pivot about the hinge pin. In a similar manner, the outboard end 37 of arm 27 is also bifurcated to locate the aligning bail 19 by a pin 38.

In FIG. 1, the aligning bail is shown as having an U shaped cross-section which locates on either side of a type face 39. Such a type face may represent the letter O which generally has parallel sides. As shown in FIG. 1, the aligning bail locates along the top and bottom parallel sides of the letter.

Each type disc 13 is cylindrical in shape having broad parallel sides and having a plurality of type characters around its periphery. The width of the type disc assures that when two or more discs are in an abutting relationship, the distance from character to character on the type discs is within the requirement of the printing drum. The broad sides of each type disc have an undercut area or recess 18 between the mounting hole 41 and the periphery. The mounting hole 41 is concentric with the periphery of the disc. A countersink is formed at each end of the mounting hole. Thus, the disc 13 is shaped like a wheel having a wide rim and a wide center hub, both parallel to the axis of the disc with a reduced web interconnecting the two.

With the previous described clamping and aligning apparatus, the following steps complete the method of fabrication. First, the clamp 15 and the arm 25 are securely mounted at one end of the shaft 11. A type disc 13 is located on the shaft by means of its mounting hole 41. The first type disc is placed adjacent to and in contact with the clamp 15. A small amount of liquid bonding material 40, such as a thermally curable liquid epoxy, is applied to the mounting hole 41 and the periphery of the shaft 11 through the countersink. Next, one or more sheets of a suitable thermosetting adhesive film 42 is located on the shaft 11 and in the recess 18 of the type disc 13. The reason for using an adhesive film in this application as opposed to a liquid form of bonding material, is to prevent the bonding material from flowing outward and adhering to the face of the type characters. A second disc 13A is then located on the shaft and is positioned against the inner surface 43 of the preceding type disc 13. A small amount of epoxy is then added to the mounting hole 41A and along the shaft 11. Then a second piece of adhesive film 42A is mounted on the shaft and against the type disc 13A. This process is continued until the desired number of type discs are assembled on the shaft. After assembling the last type disc, the clamp 17 is then located on the shaft to contain the assembled type discs in an abutting relationship 3 to each other to maintain a pressure contact between each disc. The aligning bail 19 is then brought into place along the selected type character 39, as shown in FIG. 2. The pin 38 is placed in the arm 27 and through the aligning bail securing it into position.

The step of aligning is accomplished at the type faces when all of the type discs are mounted on the shaft 11. There is no need to rely upon the quality of individual machining of the mounting holes in each type disc to have the type faces in proper alignment. The adhesive film 42 between each disc securely bonds each disc to each other disc, and the liquid epoxy 40' in the mounting holes 41 securely bonds the discs 13 to the shaft.

The assembled unit is then cured. Curing may take place at an elevated temperature, such as 330 F., for a time period of 30 minutes if the previously mentioned bonding materials are used. The time and temperature of curing is solely dependent upon the type and kind of bonding material used. After the step of curing, the aligning bail 19, the clamps 15 and 17 including the arms 25 and 27 are removed from the apparatus and the printing drum is completed.

While we have shown one particular apparatus, the aligning bail, for aligning the several type discs, there are many means which are equally satisfactory. One such means is to assemble the several type discs With the use of a magnifying projector and visually locate adjacent type characters. In order to do this, the bonding material selected should be somewhat tacky so as to hold each disc while the drum is being assembled and aligned.

Another way of aligning the type discs is to use a bail having an impression of a character in the desired axial spaced relationship of the finished drum. The character on each type disc may be accurately located in the impression and the several type discs accurately aligned one to the other.

4 It will be apparent that many changes and modifications of the several features described herein may be made without departing from the spirit and scope of the invention. It is, therefore, apparent that the foregoing description is by way of illustration of the invention rather than limitation of the invention.

What is claimed is: 1. A method of fabricating a printing drum comprising the steps of:

forming like type characters on the periphery of each of a plurality of annular discs, placing the type discs concentrically on a shaft, applying a predetermined amount of a thermally curable liquid adhesive between the periphery of the shaft and the inner periphery of each annular disc, placing a predetermined number of annular sheets of thermosetting adhesive film respectively between the adjacent sides of the discs, rotating the discs to InOVe the characters into abutting relation with a straight edge parallel to the axes of the disc while the liquid adhesive and adhesive film is uncured, and then thermally curing both adhesives to form a bond between the periphery of the shaft and the inner periphery of each disc and between each adjacent disc.

References Cited UNITED STATES PATENTS 1,576,726 3/1926 Davis 156-294 X 2,423,869 7/1947 Blessing 156-60 3,128,693 4/1964 Thiemann 101-93 3,184,355 5/1965 Brown 156-294 X 3,222,234 12/1965 De Jean et a1 264-262 REUBEN EPSTEIN, Primary Examiner US. Cl. X.R. 29-464

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