Method of preparing embossing rollers

March 21, 1967

R. MacKAY

3,309,984

METHOD OF PREPARING EMBOSSING ROLLERS

Filed Dec. 11, 1963

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United States Patent Office

3,399,984

Patentee! ~Mar. 21, 1967

-. - Λ,309)984

METHOD OF PREPARING EMBOSSING ROLLERS Robert MacKay, Lyndon, Ky., assignor to MacKay Engraving Corporation, Louisville, Ky., a corporation of Kentucky

Filed Dec. 11,1963, Ser. No. 329,791

Claims. (Cl. 101—32)

My invention is directed to a novel method of preparing embossing cylinders or rollers so that the male and female images reproduced thereon will be in register to efficiently emboss sheet material which is fed between said cylinders.

The presently known methods of preparing rollers for embossing paper, foil and other like light sheet material are relatively expenisve and involve many steps requiring a considerable amount of time. One of these prior methods includes the preparation of a male steel hardened engraved cylindrical roller having radially and outwardly projecting designs thereon and then mounting said roller in a speed driven mechanism and driving the same by coupling and gear means while simultaneously turning a second metal roller made of a relatively softer metal and thereby pressing the designs in the second softer roller to the desired depth under high compression of the male roller to form cavity images or designs in said second roller. Thereafter, the second or female roller is suitably hardened to retain small details and avoid deformation. Such method also employs a suitably mounted compensator roller to aid in maintaining registration. Embossing pressure is obtained by the aid of hydraulic rams producing relatively great pressure, and micrometer adjustment of the bearing boxes is necessary to control the depth of embossing.

Certain presently known methods have not been satisfactory due to failures of proper registration and due to undesirable variation in the depth of embossing and nonuniformity of embossing upon sheets of varying thicknesses.

It is an object of my invention to provide a novel method of preparing cylindrical embossing rollers for embossing paper, foil and other sheet material and which includes the steps of copper plating said cylinders; releasably securing said cylinders in a fixed relative position; transferring the images from a positive film and from a negative film onto said cylinders respectively in a predetermined position for subsequent registry; etching said cylinders and then mounting the same in a suitable press so as to permit sheets of suitable material to be fed between the driven rollers and thereby embossed.

A further object of my invention is the provision of a novel method of preparing cylindrical rollers for embossing recited in the preceding paragraph and in which separate positive and negative films of the design to be reproduced are releasably mounted in a releasable holding means, and the images on the positive and negative films are photographically transferred to fixed positions upon said cylinders in a manner so that such images when the etching step is completed will register.

Other and further objects of my invention will be apparent from the following description and appended claims.

On the drawings:

FIG. 1 is a top plan view of two of my embossing cylinders, with cooperating gears and power transmission mechanism and journalled in a typical position; the remainder of the press being omitted.

FIG. 2 is an end view thereof looking at the right end of FIG. 1.

FIG. 3 is an enlarged fragmentary and cross sectional view of portions of two embossing cylinders, illustrating 'a registering male member on the lower cylinder and female embossing member on the upper cylinder.

FIG. 4 is an enlarged perspective of a sheet on which letter A has been embossed.

FIG. 5 is a diagrammatic view illustrating the temporary position in which the negative and positive of a photographic reproduction is removably mounted before printing and transfer of the images upon the two cylinders respectively.

FIG. 6 is a perspective illustrating a portion of a pinbearing holding and jig bar and the positioning of the positive film prior to transfer of the image to the cylinder.

FIG. 7 is a perspective illustrating the position of one of the cylinders and of the film and of a light means positioned above a portion of the cylinder.

As shown on the drawings:

Referring to FIGS. 1 and 2, reference numeral 10 designates a cylindrical metal roller having mandrels 11 mounted in the opposite ends thereof, and which include the respective oppositely projecting secured shafts 12 and 13. The cylinder of each roller is of steel and is turned down on a lathe to a smooth cylindrical surface. The intermediate surface portion of said cylinder is then copper plated to form a copper face or layer 10α by one of the presently known electrolytic plating processes to the desired depth, which depth of plating is varied according to the depth of embossing to be performed. Said male roller 10 is provided with two annular rolling surfaces 23 and 24 which are at opposite ends of the copper skin thereof and are of smaller circumference than the plated portion thereof, prior to etching as hereinafter described.

Numeral 25 designates a steel cylindrical roller which has its intermediate portion turned down on a lathe so that such intermediate portion is of smaller circumference than the two annular end bearing faces 26 and 27 on the ends thereof which are simultaneously formed in the lathe cutting operation. Bearing faces 26 and 27 and bearing faces 23 and 24 all have substantially the same diameter. The intermediate cylindrical face of said roll 25 is copper plated to the desired depth to form a copper layer of skin 25α and which depth should be greater than the depth of the etched cavities to be formed therein. The diameter of layer 25α, before etching, is preferably approximately the same as that of the bearing faces. Said second or female cylindrical roller 25 with its cylindrical copper face 25α has end mandrels mounted on the opposite ends thereof which include oppositely projecting stub shafts 28 and 29 respectively.

The master art unit 30 bears the designs to be embossed and said designs are usually in varying textures or artistic unit in specific positions of the areas of the features to be embossed. Said art unit 30 has mounted on the end of it a relatively rigid apertured mounting strip 30α.

A photographic negative 33 is made from the master 30 and its mounting strip 30α and two holes are made in said negative film 33 positioned identically to the holes in said strip 30α of said master. A photographic positive film 42 is made from the aforesaid negative film and holes are formed in the end portion thereof in positions corresponding to the positions of the holes in said mounting strip 30α of said master 30.

A gear 20 is secured on the end shaft 13 of said lower male roller 10. A gear 43 is suitably secured upon the projecting end of shaft 29 of the female roller 25. The male roller is locked in a fixed position on a suitable support by means of a removable lug such as the lug 40 on a pivotally connected arm 41 as shown in FIGS. 6 and 7. Said lug 40 is inserted into the recesses between

3,309,984 two adjacent teeth of the gear wheel 20 to releasably hold said roller 10 in fixed position. A visible mark 32 is made on the tooth of gear 20, as shown in FIG. 7, and a similar mark is made on gear 43 to register with mark 32. Said meshing gears 20 and 43 hold the rollers 25 and 10 in registering position.

Said visible marks on gears 20 and 43 provide for properly setting the said rollers 25 and 10 in a press in registering positions so that said marks are initially in registering adjacent positions.

Each of the copper faces 10α and 25α of the rollers 10 and 25 respectively are coated with a suitable light sensitive solution, which is preferably applied by spraying.

A metal holding or jig bar 35 is securely mounted on a support (not shown) in a fixed position parallel to and spaced from said male roller 10. Said jig bar 35 has removably secured therein a pair of upwardly projecting metal pins 36 which are spaced apart a distance equal to the spacing between the holes in the end portion of the positive film 42 so that the positive film may be mounted on said pins 36 and so that said film will lie over the plated and coated face of the roller 10 and be impinged against said roller 10 by a pair of parallel spaced apart suitably journalled impression rollers 37 and 38 which are preferably formed of rubber and which hold the positive film in position prior to the photographic printing step. Said rollers 37 and 38 are journalled at their opposite ends on two rotatable lead screws (not shown). Said lead screws are manually rotated to push the rollers 37 and 38 downward to impinge the positive film 42 against the coated face of roller 10.

Thereupon, with the aid of a suitable electric light (see FIG. 7), which may be mounted in a casing or housing 39, the photographic image is transferred and printed from the positive film 42 upon the copper plated face 10α of the roller 10, said impression rollers 37 and 38 being suitably mounted for rotation and the roller 10 being released and rotated during such printing step. This printing is done after removal of the pins 36 so as to cause said positive film to lie directly on and move in contact with the cylindrical copper face 10α of said roller 10. Thereupon the face 10α of roller 10 is suitably etched in a conventional manner.

The negative 33 is similarly positioned on two of the pins 36 and beneath the impression rollers 37 and 38 and against the copper plated face 25α after said roller 25 is released from locked position in which it was held with the aid of lug 40 engaging the gear wheel 43 mounted on shaft 29. Said initial positioning is aided by alignment of the mark 32 made on the end face of a tooth of the gear wheel 43 with a mark on gear wheel 20. With the proper exposure from a light mounted within the casing 39, the image is printed from said negative in correct position upon the face 25α of the roller 25. Said roller 25 is then etched suitably in a conventional manner to the desired depth to produce cavities or recesses corresponding to the male projecting parts produced by etching of the cylinder 10.

The rollers 10 and 25 are then mounted in superposed position in suitable bearings of a press and with the alignment of the marks on their respective meshing gear wheels 20 and 43, so that their respective annular end faces 27 and 23 and faces 26 and 24 will roll in contact with each other and so that the respective male images of lower cylinder 10 will register with and seat in the corresponding image recesses of the copper face 25α of the cylinder 25. The copper plated layers 10α and 25α are made of such a thickness so that these layers are slightly spaced apart when the rollers are mounted in work position. Similarly the etching of the copper plated layers 10α and 25α is to a degree so that when the male images of the layer 10α register with and seat partly into the corresponding female images of the layer 25α, there will be a slight spacing or clearance between same to permit the sheet material to be embossed to pass there between and be simultaneously embossed. Such spacing is preferably equal to approximately one-half the thickness of the sheet material to be embossed.

The metal-to-metal rolling engagement of annular face 23 with face 27 and of annular face 24 with annular face 26 prevents undesirable wear and pressing contact between the raised embossing members of coated layer 10α and the female recesses of layer 25α, and this results in greatly increased life and period of use of my embossing rollers.

In FIG. 3, I have illustrated a fragment in cross section of the lower roller 10 having a raised projecting embossing member 45 integral with its copper layer 10α and with said member projecting in a registering cavity 46 of the copper layer 25α of roller 25. A sheet of paper 47 is illustrated in normal impinged position with an embossed portion formed thereon between the raised projecting member and said cavity.

In FIG. 4 is illustrated a typical sheet of material 47 on which the embossed image 48 has been produced in the described manner.

When said prepared embossing rollers are mounted in suitable bearings 17 and 18 in a press 19 in work producing position, with gears 43 and 20 in mesh and in proper registering position, gear wheel 21 is secured on shaft or mandrel 12 and a driving gear 51 is mounted on the projecting end of a shaft 52 of a conventional variable speed drive 50, only an end fragment of which is illustrated in FIG. 1. Said variable speed drive 50 is adapted to be operatively connected to be driven by a suitable electric motor (not shown).

The sheet material to be embossed is preferably in roll form in a continuous web which is fed at the desired speed between the embossing rolls which pull said web during normal operation. Said embossing rolls and their connected mounting means and mechanism are positioned as the last station or position relative to the printing press which reproduces the designs on the web. The adjustability of the variable speed drive is accordingly important to provide for proper speed of rotation of the embossing rollers so as to take the printed web directly from a printing press to emboss same.

While the foregoing specification sets forth the invention in spacific terms, it is to be understood that numerous changes in the shape, size and materials may be resorted to without departing from the spirit and scope of the invention as claimed hereinafter and it is contemplated that various changes may be made in the embodiment of the invention herein specifically described without departing from or sacrificing any of the advantages of the invention or any features thereof, and nothing herein shall be construed as limitations upon the invention, its concept or structural embodiment as to the whole or any part thereof except as defined in the appended claims.