US3418926A - Apparatus for printing on curved surface body - Google Patents

Description

Dec. 31, 1968 ICHIRO HAKOGI 3,418,926

APPARATUS FOR PRINTING ON CURVED SURFACE BODY Filed March 15. 1966 Sheet of 2 INVENTOR.

Dec. 31, 1968 o HAKOGI 3,418,926

APPARATUS FOR PRINTING ON CURVED SURFACE BODY Filed March 15, 1966 Sheet 2 of 2 INVENTOR.

United States Patent 9 APPARATUS FOR PRINTING N CURVED SURFACE BODY Ichiro Hakogi, Tokyo, Japan, assignor to Tomi Kogyo Kabushiki Kaisha, Tokyo, Japan Filed Mar. 15, 1966, Ser. No. 534,336

Claims priority, application Japan, Mar. 17, 1965,

40/ 15,560 16 Claims. (Cl. 101-35) ABSTRACT OF THE DISCLOSURE A printing arrangement in which chambers on opposite sides of a extensible printing film are evacuated to provide equal suction pressures on opposite sides of the film and maintain the original position of the film, one of the chambers then being subjected to positive pressure to urge the film into contact with a body in the other chamber to effect printing thereon.

The present invention relates to apparatus and methods for printing a pattern on a curved surface of a body.

The curved surface may be concave, convex or of complex curvature which is a combination of both.

The printing may be effected by an offset blanket, a pattern transfer paper or a resin impregnated paper.

The present inventor has shown in his prior patent (US. Patent No. 2,077,790) printing on a curved surface in which an elastic blanket is brought into close contact, for press printing on a curved surface of a body by utilizing a negative air pressure. Therein, air is discharged from an air-tight chamber formed between an elastic printing plate and the surface to be printed so that, by utilizing the negative air pressure, the printing plate is brought into close contact, for press printing, with the surface to be printed.

In such apparatus, however, an unavoidable deficiency is the production of an air pocket between the printing plate and the surface to be printed, depending upon the shape of the curved surface, and due to which a portion of the surface to be printed is either not printed or is not clearly printed.

It is an object of the present invention to eliminate the production of such air pockets and enable the printing on any complicated curved surface over the entire surface thereof.

According to the present invention, an extensible printing film is held under pressure between an open surface of an open casing and an open surface of a second casing in which is contained a body with a curved printing surface. Thereby there is formed two closed air chambers on opposite sides of the films, and after these two chambers have been subjected to a vacuum by simultaneously evacuating the air therefrom, the air chamber on the side opposite the body is pressurized while the air chamber containing the body is maintained under vacuum, whereby the extensible film is brought into close contact with the curved surface of the body by the difference in pressure between the two chambers.

A feature of the invention is the maintenance of the extensible film in its original position so that all of the air may be withdrawn from the chamber containing the body so that no air pockets can be formed between the film and the body during the printing operation.

In further accordance with the invention, certain films must be softened by heat prior to the printing operation. A further feature of the invention is to employ heating means in the chamber opposite the body in order to heat the film.

Another feature of the invention is to apply suction force to the heated film to hold the same in its original position against a flat surface and thereby prevent sagging of the film against the body.

A further object of the invention is to provide continuous operation wherein successive bodies are printed. For this purpose, the casings are advanced along respective endless paths along a portion of which the casings move in the same direction in contact with one another and whereat the printing is effected.

The present invention will be explained in greater detail with reference to the accompanying drawings, wherein:

FIGURE 1 is a sectional side view of a first embodiment of the invention;

FIGURE 2 is a sectional side view of another embodiment of the invention;

FIGURE 3 is a sectional side view of a further embodiment of the invention;

FIGURE 4 is a diagrammatical side view of a construction for continuous operation of the apparatus of the invention;

FIGURE 5 is a diagrammatical side view of a modified form of the same; and

FIGURE 6 is a sectional side view of an air casing used in the construction of FIG. 4.

The same reference numerals will be used throughout the various figures of the drawings to designate the same elements.

FIGS. 1 and 2 essentially differ in that in FIG. 1, the body a on which the pattern is to be printed, is generally concave whereas that in FIG. 2 is generally convex.

Referring to FIGS. 1 and 2, numeral 1 denotes a casing which is open at its bottom surface, and numeral 2 denotes a second casing which is open at its top surface and contains the body a to be printed. An extensible printing film 3 is held taut between the open surface of the casing 1 and the open surface of the casing 2 to form respective closed air chambers A and B on opposite sides of the film 3. The casings 1 and 2 are in contact along rubber or other elastic plates 4 and 5 to form air-tight seals. There is provided within the casing 2 a projecting portion 6 for receiving the body a to be printed.

When the body a is supported in the casing 2, the air within the two casings 1 and 2 is evacuated simultaneously through respective air tubes 7 and 8 in communication with the casings 1 and 2 for subjecting the chambers in these casings to a vacuum, whereby any formation of an air pocket between the curved surface of the body a and the extensible film 3 is prevented when the film 3 is brought into close contact with the body surface. Namely, as the air chambers A and B are simultaneously subjected to vacuum, the air surrounding the body a is removed completely and, at the same time, the film 3 is kept in its neutral position without deflecting towards either of the two chambers A and B by maintaining the suction pres sure in the air chamber A equal to the suction pressure in the air chamber B. This is effective to fully compensate the deficiencies in the known apparatus as described hereinbefore, wherein only the air within the chamber B containing the body a is evacuated to subject chamber B to a vacuum. In such case, at a concave portion b of the body a, the film 3 which is about to be brought into contact with the surface of the body a by the external pressure will first contact the circumferential edge of the concave portion 12, thus making it impossible to evacuate the air within the concave portion b. Accordingly, there is a danger that an air pocket will remain within the concave portion b. This is more likely when a transfer paper or a resin impregnated film is used. In particular, a resin impregnated film or the like must be softened by heat in operation, and as a result of its softening the film hangs down over the concave portion b of the body a to produce therein an air pocket. This also can be prevented according to the present invention.

After the interior of the casing 2 containing the body a has been subjcted to vacuum, the casing is kept in such condition while the casing 1 on the other side surface of the film 3 is charged with a positive air pressure. Consequently, a pressure difference exists between the two casings 1 and 2 and the extensible film 3 is pushed into the chamber B into close contact with the outer surface of the body a to conform to the curved shape thereof, without the production of any air pockets therebetween.

In the case when an Offset blanket is used as the extensible film 3, the same has a pattern transferred to its lower surface prior to its printing operation, so that when the film comes into contact with the surface of the body, the pattern is printed thereon. It is also possible that an extensible transfer paper with a pattern or a resin impregnated paper for decorative laminates is used for the film 3, so that by the close contact or the adhesion thereof with the body a, the pattern may be applied ontothe curved surface of the body. In this case, it is necessary that the transfer paper or the resin impregnated paper be softened by heat, and for this purpose there is provided heating means in the form of heating elements 9 as shown in dotted lines in FIGS. 1 and 2.

FIG. 3 shows a modified embodiment of the present invention. When the film 3 is softened by heat, there is a danger that the softened portion thereof will become limp and sag and contact the body a to cover the concave portion thereof and produce an air pocket. In this embodiment, there is provided within the air casing 1 a suction device 10 having a lower surface with suction holes 11 formed therein, so that when the film is being heated and the air within the casings 1 and 2 is being evacuated, the interior of the suction device 10 is in communication with a negative pressure source for attracting the film to the device. When the interior of the air chamher 1 is subjected to positive pressure, the suction action in device 10 is terminated to release the film therefrom.

The apparatus of the invention can be arranged for continuous operation as shown, for example, in FIGS. 4 and 5.

Therein, a number of casings 1 and a number of casings 2 are, respectively, connected in series in endless chain form, and are driven to rotate either continuously or intermittently. The casings 1 and casings 2 move along respective endless paths which have parallel adjacent lengths in which the casings 1 and 2 advance in the same directions and along which the casings 1 and 2 are applied against each other one by one.

In FIG. 4, the casing 1 is provided at its surface immediately adjacent casing 2 with the elastic blanket 3 to form in the inner side thereof the air chamber A, as shown clearly in FIG. 6. In this case, however, the casing 1 is substantially a fiat plate and consequently the air chamber A which is formed is only a flat gap. During the travel of the casings 1 at their upper length of travel, a desired pattern is transferred onto the blanket surface by a printing mechanism 12. The bodies a are introduced into lower casings 2. When the two casings 1 and 2 are placed against one another, the air pressure within these casings is control-led automatically by air tubes and switching valves for bringing the blanket 3 into close contact with the curved surface of the body to print the pattern thereon. The printed body a is discharged onto a conveyor 13 for being conveyed to the succeeding drying and other steps.

In the embodiment shown in FIG. 5, a long length of transfer paper or resin impregnated paper is used for the film 3. The rolled paper 3 is drawn out successively with the advance of the casings 1 and 2 one upon another. During this travel, the heating for softening of the film, and the pressure control of the interior of the casings 1 and 2 are effected automatically, so that a pattern is applied to the bodies by the close contact or the adhesion of the film therewith after which the bodies are discharged along with the film onto the conveyor 13.

Thereafter, if the paper is a transfer paper, the same is stripped off from the body. If, however, the paper is a resin impregnated paper, the same is separated at the portions not integral with the bodies.

From the above, it will be evident that herein has been shown apparatus and methods for printing on a curved surface of a body, wherein there is formed on opposite sides of an extensible printing film two air chambers one of which contains therein the body to be printed thereon, and wherein the air from the two chambers is simultaneously evacuated while the film is maintained in its original position, after which the air pressure in the chamber opposite said body is raised while maintaining suction in the chamber containing the body so that a pressure differential is established between the two chambers which forces the film into close contact with the surface of the body. As a result of the above, there is no danger whatever of the existence of an air pocket between the printing film and the curved surface of the body.

Numerous modifications and variations of the disclosed invention will become apparent to those skilled in the art without departing from the scope and spirit of the invention as defined in the attached claims.

What is claimed is:

1. Apparatus for printing on a curved surface comprising first and second casings secured together in sealed relation, one of said casings being adapted for containing a body having a surface which is to be printed, an extensible printing film supported between said casings and defining respective chambers on opposite sides thereof with said casing, means for simultaneously subjecting both chambers to equal suction pressure to evacuate the chambers while maintaining equal pressures on the opposite sides of the film thereby retaining the initial position of the extensible film between said casings, and means for increasing the pressure in the chamber opposite said body to cause pressure differential between the chambers which urges the film into contact with the body over the entire surface thereof and cause printing thereon.

2. Apparatus as claimed in claim 1 wherein said means for increasing the pressure in the chamber opposite said body comprising means for supplying pressure fluid to such chamber.

3. Apparatus as claimed in claim 1 comprising heating means in the chamber opposite said body for heating the printing film.

4. Apparatus as claimed in claim 3 comprising means in said chamber which is opposite said body for applying suction force to said film to hold the same thereagainst and thereby prevent sagging of the film.

5. Apparatus as claimed in claim 4 wherein said means for preventing sagging of the film comprises a hollow suction device having a surface facing said film which is provided with a plurality of openings, said suction device being adapted to hold the film against said surface with said openings as a result of suction applied to said film via said openings.

6. Apparatus as claimed in claim 1 comprising means supporting each of said casings for movement along respective endless paths in a portion of which the casings move in the same direction in contact with one another.

7. Apparatus as claimed in claim 6 wherein the film is secured to the other of said casings, the apparatus further comprising means for printing a pattern on said film as said other casing moves along its path outside said portion in which the casings are in contact.

8. Apparatus as claimed in claim 6 comprising conveyor means for receiving the body from said one casing after printing of said body.

9. Apparatus as claimed in claim 6 wherein said film is in the form of a roll and is fed between the casings along said portion where the casings contact one an- 5 other, the film and body being discharged together from said one casing after the body has been printed.

10. Apparatus as claimed in claim 1 wherein the extensible film is an ofifset blanket.

11. Apparatus as claimed in claim 3 wherein the film is a transfer paper.

12. Apparatus as claimed in claim 3 wherein the extensible film is a resin impregnated paper for decorative laminates.

13. A process for printing on a body having a curved surface comprising forming on opposite sides of an extensible printing film two air chambers one of which contains therein a body to be printed thereon, simultaneously evacuating all the air from the two chambers to provide equal suction pressures on opposite sides of the film thereby to maintain the film in its original position, and then raising the air pressure in the chamber opposite said body While maintaining suction in the chamber containing the body, so that a pressure difference is established between the two chambers which forces the film into close contact with the surface of the body.

14. A process as claimed in claim 13 comprising heating said film from within the other of said chambers.

15. A process as claimed in claim 14 comprising sucking the film against a surface Within said other chamber 6 to retain the same in its original position and prevent sagging.

16. A process as claimed in claim 13 comprising holding the film initially taut between the chambers.

References Cited UNITED STATES PATENTS 2,435,224 2/ 1948 Klopfenstein et -al. 10135 XR 2,547,602 3/1951 Schmitt 10144 XR 2,645,870 7/1953 Smith et al 10140 XR 2,647,337 8/1953 Martin.

2,700,629 1/ 1955 Townsend.

2,745,339 5/1956 Fernandez 10141 3,090,296 5/1963 Pechmann 10144 3,170,393 2/1965 Reinke 101426 XR 3,253,538 5/1966 Rudolph et a1 10140 FOREIGN PATENTS 211,719 2/ 1924 England.

ROBERT E. PULFREY, Primary Examiner.

JOHN R. FISHER, Assistant Examiner.

U.S. Cl. X.R. 10144, 426, 336

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