GB2193927A

GB2193927A - A method and apparatus for applying decalcomanias

Info

Publication number: GB2193927A
Application number: GB08618476A
Authority: GB
Inventors: Kenneth Marshall; Wilfred Roberts; John Barrie Turner
Original assignee: British Ceramic Research Ltd
Current assignee: British Ceramic Research Ltd
Priority date: 1986-07-29
Filing date: 1986-07-29
Publication date: 1988-02-24
Anticipated expiration: 2006-07-29
Also published as: GB2193927B; GB8618476D0

Abstract

This is an improvement on the method described in Specification G.B. 2 141 384A in which a thermoplastics sheet carrying decalcomanias was perforated to permit application of portions of the sheet to articles. In the improved method an unperforated sheet (2) of thermoplastics carrying printed design motifs (4) is held across an aperture (15) in a table (13) by a suction ring (16) which encircles the aperture. A hot article, such as a plate (38), to be decorated and a domed pad (33) are brought against the held portion of the sheet from opposite sides to sandwich the sheet, and the pad and article are then moved together relative to the table (13) to sever the sheet around the edge of the article. The severing of the sheet arises from the softening of the sheet by the hot article, and this method of severing produces a neat edge to the severed sheet coinciding with the edge of the article. <IMAGE>

Description

SPECIFICATION A method and apparatus for applying decalcomanias This invention relates to a method and apparatus for applying decalcomanias to articles such as articles of ceramic ware.

In our Patent Application G.B. No. 2 141 384A we have described a method and apparatus for applying to an article of ceramic ware a decalomania which comprises a design motif carried by a thermo-plastics sheet. The present invention relates to significant improvements to that method and apparatus.

In the method described in Patent Application G.B. No. 2 141 384A a thermo-plastics sheet in strip form is first printed with the design motifs in ceramic colours. A perforating assembly is then employed to perforate the sheet so as to surround each design-bearing portion with a line of perforations. At an application station a portion of the unrolled sheet is held in the region surrounding the perforations, and a resiliently deformable pad is punched through the sheet to sever the design bearing portion from the held portion of the sheet at the perforations, and to carry the design-bearing portion against the heated ware which is positioned adjacent to but spaced from the held sheet. The design-bearing portion sticks to the heated ware on contact therewith due to the tack produced by the rise in temperature of the thermo-plastics sheet.On firing of the ware the thermo-plastics material is burnt away to leave the ceramic colours.

In the apparatus described by way of example the perforating assembly and pad assembly are mounted on a carriage and are alternately brought into position at the application station to perform respectively the perforation and the punching step.

A disadvantage of that earlier method is that sometimes creases are produced in the design-bearing portion of the sheet which can remain in the applied sheet.

We have realised that during the short period of travel between severing of the designbearing portion of the sheet and its application to the ware the sheet portion was unheated and therefore lacked conformability. The conformability and tack were developed simultaneously as the pad pressed against the ware.

It was found that the geometry of the pad and ware in that process is critical if creasing is to be avoided.

Another disadvantage is that the requirement for a perforating assembly adds considerably to the complexity of the apparatus and slows down the production rate.

According to one aspect of the present invention a method of applying a colour design to an article comprises taking a sheet of thermo-plastics material to a portion of which a design in ceramic colour has been applied, urging the design bearing portion of the sheet into engagement with the surface of a hot article with a resiliently deformable pad so that the design bearing portion is sandwiched between the pad and the article and, whilst the sheet is held in a region surrounding but spaced from the sandwiched portion, moving the pad and article substantially simultaneously relative to the held portion in a direction substantially normal to the plane of the held portion by an amount sufficient to cause severing of the sheet in the area adjacent to the margin of the sandwiched portion of the sheet, the film strength of the sheet in that area having been reduced due to softening.

Thus, instead of punching through the preperforated sheet with the pad, the pad and hot article with the sheet sandwiched between them are moved together to sever the sheet which need not be pre-perforated.

The held portion of the sheet is preferably held by a suction ring.

The direction of movement of the pad and article to sever the sheet is preferably such as to pull the sheet against the suction ring.

Preferably the article is initially located at a position spaced from the sheet, and the sheet is held prior to the pad being brought against the sheet to urge the sheet against the article.

According to a second aspect of the invention we provide apparatus for applying a decalcomania to an article, the decalcomania comprising a sheet of thermo-plastics material to which a design in ceramic colour has been applied, the apparatus comprising sheet holding means to hold a portion of the sheet which encircles an aperture over which the sheet extends, an article support positioned on one side of the aperture, and a pad support for a resiliently deformable pad mounted on the opposite side of the aperture, first reciprocating means for reciprocating the pad support, and second reciprocating means for reciprocating the article support, both in directions substantially normal to the plane of the held sheet, and control means arranged to control the sequence of operation of the first and second reciprocating means to perform the movements of the pad support and article support to move the pad and article in accordance with the first aspect of the invention.

According to a third aspect of the invention a method of applying a colour design to an article comprises taking a sheet of thermoplastics material to a portion of which a design in ceramic colour has been applied, heating said portion to develop some conformability therein, and urging said portion of the sheet into engagement with the surface of a hot article with a resiliently deformable pad.

Preferably the heating of said portion to develop conformability is achieved by positioning the hot article adjacent thereto, prior to the application of the pad.

A method and apparatus in accordance with the invention will now be described, by way of example only, with reference to the accompanying schematic drawings which show in sequence the stages of applying a decalcomania to an article of ceramic ware.

The preparation of the decalcomania can be as described in Application G.B. No. 2 141 384A with reference to Figure 1 of that Application, and the apparatus shown in Figures 2 and 3 of that Application is suitable for hand -ling the roll of decal sheet and for disposing of the sheet remnants after the design-bearing portions of the sheet have been applied to the articles.

The same reference numerals have therefore been used for parts of the present apparatus which are the same as the parts shown in the drawings of that earlier Application.

With reference to the accompanying Figure 1, this shows a length of the sheet strip 2 which has just been brought to the operating station 5 by the reciprocating carriage 8, not shown here, the strip 2 carrying a printed design motif 4 in ceramic colour, which is preferably on the underside of the strip 2 to ensure clean burn off of the film without risk of damage to the design motif. An article of ceramic ware, such as plate 38, has been loaded onto the support 37 which incorporates a vacuum supply 45 for holding the plate 38 firmly onto the support.

Suitable automatic means of known type, not shown, is provided for loading and unloading the support 37 with a heated plate 38 when the support 37 is in the downwardly retracted position shown in Figure 1.

The support 37 is then raised to the posi tin shown in the accompanying Figure 2 in which the plate 38 is in register with the hole 15 in the fixed table 13 and is spaced downwardly from the sheet 2 which is now held in a straight condition on the table 13 by suction applied to suction ring 16.

Since the hot plate 38 is now close to the sheet 2, the portion of sheet 2 within hole 15 is heated by the plate to develop some conformability in the sheet.

With reference to the accompanying Figure 3, the pad support plate 34 is then driven down by a suitable rnm, not shown, to force the pad 33 downwards, to urge the designbearing portion of the sheet 2, that portion within hole 15, against the upper surface of the stationary plate 38 so that the sheet is deformed to conform to the shape of the upper surface of the plate.

The heating of the article is arranged such that the temperature of the article when contacted by the sheet is sufficient to cause the sheet 2 to stick to the plate. The use of a domed pad 33 ensures that the sheet 2 is progressively pressed into contact with the article, the central portion of the design-bearing portion initially contacting the article, followed by a spreading radially outwards of the area of contact.

As compared with the method of No. 2 141 384A, the design bearing portion of the sheet 2 has developed some conformability, due to heating by the plate 38, before it is urged by the pad against the ware. This reduces the chances of creasing of the sheet occurring.

With reference to the accompanying Figure 4, the pad 33 and support plate 37 are then moved in unison sharply downwards relative to the fixed table 13 whilst the suction ring 16 is still holding the sheet 2 around the hole 15. This movement results in a neat severing of the sheet 2 immediately adjacent to the radially outer margin of the plate 38. The sheet 2 is substantially softened at the plate edge by heat from the plate, and the speed and amount of movement of the pad and plate is chosen to ensure that severing of the softened sheet occurs at the plate margin, the breaking strength of the sheet at the plate margin being low due to softening. Only a small amount of downward movement of the pad 33 and support plate 37 is required to sever the sheet 2, as shown by a comparison between the accompanying Figures 4 and 3, the severing process being compiete in Figure 4. The severed edge of the sheet is neat and coincides precisely with the plate margin.

Finally, as shown in the accompanying Figure 5, both the pad 33 and support plate 37 are retracted to permit the plate to be unloaded for a new cycle to commence.

The method described is capable of providing a much clearer cut to the edge of the cut sheet than when perforations are employed.

Since the sheet breaks substantially at the edge of the article there will not usually be any substantial overlap of the sheet edge with the plate.

When the transfers have been applied the ware can be processed in the normal ceramic manner to produce a decorated item, the thermo-plastics material being burnt away to leave the ceramic colours.

Examples of suitable materials for the pad and thermo-plastics sheet are given in our earlier Application.

Claims

1. A method of applying a colour design to an article comprising taking a sheet of thermoplastics material to a portion of which a design in ceramic colour has been applied, urging the design bearing portion of the sheet into engagement with the surface of a hot article with a resiliently deformable pad so that the design bearing portion is sandwiched between the pad and the article and, whilst the sheet is held in a region surrounding but spaced from the sandwiched portion, moving the pad and article substantially simultaneously relative to the held portion in a direction sub stantially normal to the plane of the held portion by an amount sufficient to cause severing of the sheet in the area adjacent to the margin of the sandwiched portion of the sheet, the film strength of the sheet in that area having been reduced due to softening.

2. The method of Claim 1 in which the held portion of the sheet is held by a suction ring.

3. The method of Claim 2 in which the direction of movement of the pad and article to sever the sheet is such as to pull the sheet against the suction ring.

4. The method according to any of the preceding claims in which the article is initially located at a position spaced from the sheet, and the sheet is held prior to the pad being brought against the sheet to urge the sheet against the article.

5. A method of applying a colour design to an article substantially as herein described with reference to the accompanying drawings.

6. Apparatus for applying a decalcomania to an article, the decalcomania comprising a sheet of thermo-plastics material to which a design in ceramic colour has been applied, the apparatus comprising sheet holding means to hold a portion of the sheet which encircles an aperture over which the sheet extends, an article support positioned on one side of the aperture, and a pad support for a resiliently deformable pad mounted on the opposite side of the aperture, first reciprocating means for reciprocating the pad support, and second reciprocating means for reciprocating the article support, both in directions substantially normal to the plane of the held sheet, and control means arranged to control the sequence of operation of the first and second reciprocating means to perform the movements of the pad support and article support to move the pad and article in accordance with the method of Claim 1.

7. Apparatus as claimed in Claim 6 and substantially as described herein with reference to the accompanying drawings.