GB2145036A - Embossing apparatus - Google Patents

Abstract

Apparatus for hot foil embossing comprises a head (Fig. 1), adapted to receive and hold a variable array of embossing typefaces 17; means 15 to heat the typefaces in the head; a baseplate (Figs. 11 and 12), preferably unheated and possibly heat- insulated; and means (34, 35) which, in use, locate the baseplate between the head and a workpiece on which the baseplate stands (or against which it is pressed) and which constrain the head to move past the baseplate in order to emboss the workpiece. <IMAGE>

Description

SPECIFICATION Embossing apparatus The invention relates to embossing apparatus and is particularly applicable to apparatus suitable for hot foil embossing.

It is known to emboss calendars and other relatively thin sheet card articles by a technique known as hot foil blocking or printing.

A printing head contains heated typefaces and is joined to a baseplate. The workpiece, for example a sheet of thin card, is sandwiched together with a suitable foil between the head and the baseplate. Usually the head is pivoted to the baseplate, and moves in an arc to bring the heated typeffaces into contact with the foil and the workpiece surface. Preferably there are means to positively clamp the head against the baseplate, and so keep the card and foil under substantially constant pressure, throughout the embossing operation.

Using this known technique, the surface of the workpiece is embossed, and the metallic constituent of the foil is fused and pressed into the embossed areas.

The effect so produced is essentially surface printing. The embossing depth is probably no more than 0.001 inches. If the printed surface was repeatedly rubbed, for example by too frequent handling, the foil would wear away from the embossed areas.

An embossing apparatus embodying the present invention comprises a head, adapted to receive and hold a variable array of embossing typefaces; means to heat the typefaces in the head; a baseplate, preferably unheated and possibly heat-insualted; and means which, in use, locate the baseplate between the head and a workpiece on which the baseplate stands (or against which it is pressed) and which constrain the head to move past the baseplate in order to emboss the workpiece.

With such an apparatus, because the workpiece is not sandwiched between the head and the baseplate, the thickness of the workpiece is immaterial. It is only necessary for the surface of the workpiece to consist of material suitable for embossing. The overall size and shape of the workpiece surface similarly are not crucial.

Such an apparatus therefore lends itself ideally to embossing such things as the plastics cases of electronic typewriters, dictating machines, video sets, tape recorders and similarly easily stolen equipment. If the owners house number and postcode, for example, are hotfoil embossed into such articles in a prominent position and in an eye-catching metallic finish, a would-be thief is less likely to take them.

Advantageously the head of the apparatus may be constrained, in use, to move past the baseplate in a substantially straight-line action in order to emboss the workpiece. Greater embossing depths are then possible whilst still resulting in a sharply defined embossed pattern. If, by contrast, the head was constrained to move in an arc, like the head of the known cardblocking press outlined above, the embossed pattern might blurr as the typefaces sank into and out of the workpiece surface.

It is not necessary, within the broadest aspect of the invention, for the head to be permanently located on the baseplate. Indeed it may prove advantageous not to do so, since the heating means and typefaces would more easily be serviced without the baseplate in the way.

The baseplate may advantageously be specifically adapted to locate the foil adjacent the surface of the workpiece. This aids a clean transfer of metallic finish into the embossed areas.

In a presently preferred embodiment of the invention, the baseplate exhibits a throughslot; a foil is located across the slot, in use, via channels in the baseplate; and the head is provided with a heat-insulated handle, is initially separate from the baseplate, and is located thereon in use by spring loaded pegs against which a user pushes the handle to move the typefaces into and through the slot in the baseplate and so emboss the foil into that region of the workpiece surface which is beneath the slot.

Such an embodiment will now be described with reference to the accompanying drawings in which: Figures 1 and 2 show the heated head of the apparatus in side elevation and end elevation respectively; Figures 3, 4 and 5 show parts of the head diagramatically; Figures 6, 7 and 8 show the body, which forms part of the head, in side elevation and end elevation and plan respectively;, Figures 9 and 10 show the typeface-carrying case, which also forms part of the head, in underplan and end elevation respectively; Figures 11 and 1 2 show the baseplate in underplan and side elevation respectively; and Figure 1 3 shows a carrying case for the apparatus.

In figures 1 and 2, a straight circularsection shaft is referenced 11 and is clad along its length with a heat-insulating plastics coating 1 2 which exhibits finger identations 1 3 and which functions, in use, as a handle.

The shaft projects at right angles from the centre of an initially solid rectangular boxshaped body 14 which carries a 'pencil' heating element 1 5 and a temperature-sensing probe (not shown): the shaft 11 is made of steel, the body 14 is made of brass.

A case 16, also made of brass, dovetails into a suitably machined recess in the body 1 4 and carries the variable array of individual typeface blocks 1 7 which, in use, emboss the desired workpiece. As shown in figure 4, each block 1 7 is of rectangular cross section and is straight and elongate. The blocks 17, like the case 1 6 and body 14, are made of brass in order to conduct heat most readily from the element 1 5 to the actual typefaces such as the one 1 8 indicated in figure 4 and in figure 1.

As figure 5 shows, the shaft 11 is externally screwthreaded at each of its opposite ends. It is also hollow throughout its length;one of its ends screwthreads into the centre of the body 14, tightening into a similarly screwthreaded bore 19; and a temperaturesensing 'pencil' type probe is inserted down the hollow shaft 11 and is a close fit in a bore 21 extending from the base of the blind bore 19. The bore 21 opens on to the base of the dovetailed recess 22 machined along the length of the body 14. In use, the probe (which is not shown in any of the drawings, but is similar in appearance to the heating element 1 5) will be inserted as far as the base of the recess 22; and will thus contact the mating base of the typeface-carrying brass case 1 6. Figures 6, 7 and 8 show these details.Also shown in these figures is a channel 23 which runs from the bore 1 9 down to the bore 24 which houses the heating element 1 5. In use, as figure 1 partly illustrates, the twin electrical leads supplying the element 1 5 are housed in the channel 23 and travel up through the hollow shaft 11 to emerge, together with the probe leads, from the projecting end of the handle.

The brass case 1 6 is an easily sliding but nevertheless close fit in the body 14. An end plate 25 is screwed to one end face of the body 14 and acts as a backstop when the case 16 is initially slid home. Another end plate 26 is then screwed to the opposite end face of the body 14 to hold the case 1 6 in the body 14.

A top plate 27 screws down on to the top surface of the body 14 after the heater 1 5 has been installed in its bore. The plate 27 hides the electrical leads to the heater, and is drilled out centrally to accommodate the shaft 11.

Figure 9 shows the case 16 in underplan.

Three channels 28 are machined into its underside. Each is so sized as to take a line of the typefaced blocks 1 7. Holes 29 are drilled and tapped through one end of the case 1 6 to open out into these three channels 28. As figure 1 shows, screws 31 enter the holes 29 and, when driven hard against the adjacent end block 17, hold each row of typeface blocks tightly but removably in its casing channel 28.

Four blind holes 32 are drilled one at each opposite corner of the underside of case 1 6.

They project up in to the material of the case, but they do not pass right through it. In use, as will become apparent, they locate the casing 1 6 (and hence the head as a whole) on the baseplate of the apparatus; which will now be described in detail with reference to figures 11 and 1 2.

The baseplate is rectangular in plan, and four pegs 34 project from its corner regions.

Each of these pegs is of identical height, and each screws in to a drilled and tapped hole in the base. Each peg has a compression spring 35 coiled around it, and these springs 35 project beyond the end of their respective associated pegs.

The springs 35 are a close fit within the blind bores 32 drilled into each corner of the underside of case 1 6 and shown in figure 9.

A user grasping the handle 1 2 of the head of the apparatus can thus move the head towards and away from the baseplate assembly, against the action of springs 35. Pegs 34 and springs 35 together with bores 32 constrain the head to move in a straight-line action towards and away from the baseplate.

The baseplate itself is a composite assembly of top plate 36, bottom plate 37 and spacing plates 38. A through-slot 39 is cut out of both the top plate 36 and bottom plate 37, and the spacing plates 38 create side gaps 39A into which a foil sheet can be fitted and located across the through-slot 39.

In use, the baseplate stands on or is pressed against the surface of a workpiece to be embossed. Typeface blocks 1 7 are loaded presses the head against the action of springs 35 towards the baseplate. This moves the typefaces through slot 29 and presses them hard against that region of the workpiece surface which is beneath the slot. Continued pressure embosses the workpiece surface with the foil finish, and the head can then be retracted and if necessary separated from the baseplate assembly by lifting it off springs 35.

The working dimensions and parameters of the apparatus can readily be selected by the man skilled in this particular field. The heating element 1 5 could for example be a 240 volt 250 watt standard element. The probe could be set to keep the heating element switched on as long as the temperature of the typefaces in casing 1 6 remain around 150"C. If the temperature rises substantially above that, the probe would automatically cut out the heater, and bring it back in again when the temperature fell below that value. When embossing plastics such as the casing of a transistor radio or dictating machine, these figures might be appropriate, and the embossing depth could lie between 0.001 inches and 0.005 inches.

Suitable foils are already known and need not be described here.

The underside of the bottom plate 37 of the baseplate assembly could exhibit double sided adhesive tape, to help the baseplate stick to whatever surface was being embossed. Suction pads could achieve the same effect. Although individual typeface blocks have been illustrated, it could prove possible to arrange a variable array of typefaces with each line of typefaces carried on a heated rotatable belt or wheel.

The embossed characters need not, of course, be restricted to letters of the alphabet; and the term 'typeface' is to be given a suitably broad interpretation.

In figure 1 3 a ridded case houses the printing head and baseplate assembly previously described. The electrical leads to the heating element run out to a junction box which, on its outside surface, incorporates a plug socket 41.

A thermostat 42 allows the user to set a desired temperature for the typefaces and hence to set the probe to govern the output of the heating elements 1 5 aecordingly. Foil sheets 43 are dispensed from a continuous roll, and a tray 44 either 1ifs5 out vertically or slides out horizontally to give access to the interior of the case for storage and removal of the embossing apparatus.

Mains power is of course fed to the heater of the apparatus from an extension lead plugged in to the socket 411. The electrical leads from the other side of that socket to the heating elements are left sufficiently long for the embossing apparatus to be removed from the casing before being used.

In the apparatus described and illustrated herein, the baseplate components 36, 37, 38 are all made of a suitable heat-insulating plastics material.

Also, in the described apparatus, the embossing depth is set automatically when the projecting ends of pegs 34 come up against the bases of blind holes 32 (or alternatively when the underside of body 14 contacts the top of baseplate 36). Once the appropriate surfaces have come into contact as the head is pushed towards the baseplate, the typefaces cannot sink beyond the predetermined depth.

Claims (1)

1. Embossing apparatus comprising a head, adapted to receive and hold a variable array of embossing typefaces; means to heat the typefaces in the head; a baseplate, preferably unheated and possibly heat-insulated; and means which, in use, locate the baseplate between the head and a worfrpiece on which the baseplate stands (or against which it is pressed) and which constrain the head to move past the baseplate in order to emboss the workpiece.

2. Apparatus according to Claim 1 and in which the head of the apparatus is constrained, in use, to move past the baseplate in a substantially straight-line action in order to emboss the workpiece.

3. Apparatus according to Claim 1 or Claim 2 in which the head is permanently located on the baseplate.

4. Apparatus according to any of the pre ceding Claims and intended for hot foil em- bossing, and characterised in that the baseplate is specifically adapted to locate the fruit adjacent the surface of the workpiece.

6. Apparatus according to Claim 5 and in which the baseplate exhibits a throusatl-slot, a foil is located across the slot, in use, via channels in the baseplate; and the head is provided with a heat-insulated handle, is initially separate from the baseplate, and is located thereon in use by spring loaded pegs against which a user pushes the handle to move the typefaces into and through the slot in the baseplate and so emboss the foil into that region of the workpiece surface which is beneath the slot.

7. Apparatus substantially as described herein with reference to and as illustrated in the accompanying drawings.