GB2612768A

GB2612768A - Embossing plate and method for producing

Info

Publication number: GB2612768A
Application number: GB2115805.0A
Authority: GB
Inventors: Stephen Cook Christopher
Original assignee: Cook Brothers Ltd
Current assignee: Cook Brothers Ltd
Priority date: 2021-11-03
Filing date: 2021-11-03
Publication date: 2023-05-17
Also published as: GB202115805D0

Abstract

An embossing plate comprises a first sheet of material 10, at least one panel 16 formed from a second sheet of material. The first sheet has at least one recess 15 formed therein, and each recess has one or more holes 12 extending through the first sheet. The holes are arranged in a configuration corresponding to a desired embossing pattern. Each panel has a base with dimensions corresponding to those of each recess, and further comprises one or more raised projections extending from the base. The projections are complementary to the holes and arranged in a configuration corresponding to the desired embossing pattern. Each panel is mounted and secured in each recess, such that the raised projections protrude through the holes. Both sheets of the embossing plates may be formed from steel using a machining process. The panels may be secured in the recesses using welding or taping. The invention may be used for printing braille onto pharmaceutical packaging.

Description

Embossing Plate and Method for Producing This invention relates to an improved method for producing an embossing plate, embossing plates produced by such a method, and embossing apparatus incorporating such embossing plates.

The present invention relates in particular to embossing plates having patterns of raised dots, such as braille, for blind and visually impaired people. The invention further relates in particular to such embossing plates for providing embossed patterns in a range of specialised applications where quick and easy identification of the relevant patterns is particularly important, such applications including pharmaceutical /o packaging. The invention will therefore be described herein with particular emphasis on such applications. It is envisaged however that the invention may be adapted for a wide range of other applications where the provision of embossed patterns is desirable.

It is known to produce embossing plates for braille, and other embossed patterns, from a range of materials, including brass plates. These can be machined down, starting from a relatively thick plate, to produce a machined plate with a reduced thickness, for example of around 10% of the original thickness across most of its area, but with the desired raised protrusions remaining at specific locations. These protrusions will typically have a significant residual height above the base plate, and have a domed top. The exact configuration of the protrusions will depend on the specific application, however the protrusions may desirably take the form of a set of dots or pins, arranged in clustered blocks of varying numbers. Alternatively, the protrusions may desirably form a pattern such as a cross or triangle. The specific pattern will generally repeat at defined spacings across the plate, often arranged in rows and columns. -2 -

Machining these plates to the accuracy required over the size of the plate, is challenging but a tolerance of between 11 to 40 microns across the plate can be achieved.

Once machined, the plate is typically wrapped around a steel cylinder and is then run against an opposing cylinder with a rubber coating or other impressable material, to impress the raised dots onto a sheet of material to be embossed, which is sandwiched between the cylinders. Alternatively, the machined plates can be used on opposing flat pattens in a flat bed press.

The use of brass as the material from which to machine the plates has certain advantages in that it is easily machinable as so will typically generate less heat during the machining process, and will warp less than harder materials such as steel. However, brass does not have the same wear resistance as well as other metals, notably steel, leading to a shorter viable lifespan for the plate.

It is therefore desirable to produce embossing plates from steel, which is harder wearing, and more resistant to the wear described above. However, steel plates could not reliably be manufactured by the above described machining process, as the heat generated would be likely to cause warping and inaccuracy. The time required to machine steel plates would also make the cost and delivery time prohibitive.

Known steel embossing plates are currently produced by a combination of 20 etching and machining processes. The steel plates used tend to start at between 1.5 to 2 mm thickness, requiring an energy intensive machining process generating significant amounts of carbon dioxide.

The present invention provides an improved method for producing an embossing plate which method is suitable for use with steel, without causing warping or loss of accuracy. -3 -

According to a first aspect of the present invention there is provided a method of producing an embossing plate, comprising the steps of: (i) in a first sheet of material, forming at least one recess over a portion of the area of said first sheet and at one or more pre-determined locations corresponding 5 to a desired embossing pattern; (H) forming one or more holes through the first sheet, in the or each recess, said holes being arranged in a configuration corresponding to said desired embossing pattern; (Hi) from a second sheet of material, forming at least one panel having a base with dimensions corresponding to those of the or each recess, and further comprising one or more raised projections extending from the base, said projections being complementary to the holes, and arranged in a configuration corresponding to said desired embossing pattern; (iv) mounting the or each panel in the or each recess, such that the raised projections protrude through the holes; and (v) securing the or each panel in place in the or each recess.

The first sheet and the second sheet are preferably both formed from steel. The sheets may be formed from the same grade of steel, or alternatively it may be desirable for the second sheet to be formed from a different grade of steel. In 20 particular, the second sheet may preferably be formed from stainless steel.

Each of the recesses formed in step (i), the holes formed in step (ii), and the panels and projections formed in step (iii) is preferably formed by a machining process.

The or each recess is preferably formed such that the depth x thereof is substantially half of the thickness y of the first sheet over the remainder of its (unmachined) area. The or each panel is preferably formed such that the thickness z -4 -of the base is substantially equal to the depth x of the or each recess, and wherein the height w of the raised projections above the base is significantly greater than (y -x) where y is the thickness of the first sheet over its unrecessed area.

The thickness y of the first sheet may typically be 0.2mm, with the machined depth x of the recess formed in step (i) being 0.1mm. The width and length of the recess will typically be lOmm x lOmm, or alternatively may be 5.5mm x 5.5mm. The holes machined through the sheet in step (ii) will typically have a diameter of 1.5mm to 2mm, and will be located centrally in the recess.

The second sheet may typically have an unmachined thickness of 1.5mm. After the machining process of step (iii), the resultant panel will typically have a thickness z at its the base of 0.1mm, whilst the width and length of the panel will typically be lOmm x lOmm.

The raised projections formed in step (iii) may typically have a height of 1.3mm above the base plate, and take the form of domed dots or pins, preferably arranged in 15 a group of 4, though they can be arranged in any desired number or configuration Securing of the or each panel in the or each recess may be effected by a process selected from welding or taping. A further alternative is for the inserted panel to be woven through the first sheet, with pins securing it from movement. In this arrangement, the sheets are machined with an extended recess to accommodate the 20 overlap, so as to keep a constant thickness. Where welding is used, this may be carried out by micro laser welding.

Taping however is generally preferred, since this provides the additional advantage of enabling the or each panel to be removed and replaced easily when the raised projections wear. A second larger and shallower recess, surrounding or -5 -extending to either side of the or each main recess, may be machined in the first sheet to accommodate the thickness of the tape.

Preferably, in step (i) a plurality of recesses are formed at spaced locations across the first sheet, and in step (iii) a plurality of corresponding panels are formed, said panels then being mounted and secured in said recesses in steps (iv) and (v).

The present invention also provides an embossing plate produced by the method according to the first aspect of the present invention, as hereinbefore described.

Therefore, according to a second aspect of the present invention there is 10 provided an embossing plate comprising: (a) a first sheet of material, having at least one recess formed therein over a portion of the area of said first sheet, the or each recess having formed therein one or more holes extending through the first sheet, said holes being arranged in a configuration corresponding to a desired embossing pattern; and (b) at least one panel formed from a second sheet of material, the or each panel having a base with dimensions corresponding to those of the or each recess, and further comprising one or more raised projections extending from the base, said projections being complementary to the holes, and arranged in a configuration corresponding to said desired embossing pattern; and wherein the or each panel is mounted and secured in the or each recess, such that the raised projections protrude through the holes.

The scope of the present invention also extends to embossing apparatus incorporating an embossing plate according to the second aspect of the present invention as hereinbefore described. -6 -

The embossing plate produced by the method of the present invention provides a number of advantages over prior art steel embossing plates as hereinbefore described. Firstly, the smaller panels can more easily be accurately machined compared to machining over a larger area. Secondly, the main plate is formed by the first sheet in one piece, and is thus extremely accurate. Thirdly, the smaller panels can easily be replaced in the event of wear, which is of particular benefit in the event of uneven wear across the plate; the viable lifespan of the plate can thus be prolonged, where it would conventionally be prematurely wasted. Fourthly, the smaller panels can be treated in a number of ways to improve hardness and/or wear resistance. A full-sized machined plate would be too large for most such processes. And fifthly, producing embossed plates by the method of the present invention significantly reduces (by 8 to 10 times) the amount of carbon dioxide generated, as compared to known etching-machining processes starting from full thickness steel plates.

One particular application of the present invention relates to the production of braille tools for embossing pharmaceutical packaging. An embodiment of the present invention is adapted for this use.

Known (prior art) braille tools for embossing pharmaceutical packing are machined from a solid sheet of brass. The female part of the tooling is 'universal', having all 6 holes for each braille letter, and can be machined into a variety of materials including nylon, aluminium and epoxy resins. The male part is formed with a configuration of raised dots specific to a particular letter, symbol or character. The female part being universal allows for different male parts (referred to as 'counterforces') to be used in the same female die, with the female die forming part of the cut & crease die used in the manufacturing process to produce the pharmaceutical packaging. In this way the bulk of the tooling can be reused for different braille wording -7 -on different print runs for the same size box. The brass braille male counterforce is held within a matrix counter, which forms the counterforce to the creasing part of the cut crease die. This is typically between 0.5mm and 1.5mm thick and is stuck to a thin steel plate with double sided tape. A separate steel plate with matrix counters and braille male counterforces is needed for each different job The embodiment of the present invention adapted for this use provides an improved system having the advantages described above relating to forming embossing plates from steel rather than brass or other suitable materials, namely enhanced wear resistance and hence an increased viable lifespan for the product.

In the said embodiment, the first sheet of material is a thin steel mesh plate.

Each recess formed therein corresponds to a braille cell, with the holes formed through the first sheet, in the or each recess, being arranged in a configuration corresponding to all the 6 dot positions of each braille cell, as per the universal female. The panels formed from the second sheet then take the place of the male braille counterforce, with each said panel being formed with a specific configuration of raised dots corresponding to the relevant braille letter, symbol or character.

To enable the adapted embossing plate of the said embodiment to be utilised in existing apparatus, a thin magnetic holding plate may be provided, to fit within the matrix counter where the male Braille part would normally be located. This will be approximately 0.6mm thick with magnets within and a recessed pocket in the front similar to magnetic systems utilised with magnetic embossing die holders. The counterforce can then be placed into this magnetic pocket to be held in the precise desired position. This counterforce can then easily be removed, reused, and a new counter with different wording made from its components. In this way the steel plate and matrix counters can now also be reused on every job as well as all the components -8 -of the Braille male counterforce. This would be supplied with full alphabets to enable the customer to be able to produce their own Braille male counterforces with the re-useable parts.

In order that the present invention may be clearly understood, a preferred 5 embodiment thereof will now be described in detail, though only by way of example, with reference to the accompanying drawings, in which: Figure 1 is a front perspective view of a first sheet, constituting a first component of an embossing plate according to the present invention; Figure 2 is a rear perspective view of the sheet of Figure 1; Figure 3 is an enlarged perspective view of a detail of Figure 2, namely a recess formed in the sheet; Figure 4 is an enlarged perspective view of a panel, constituting a second component of an embossing plate according to the present invention; Figure 5 is a front view of an assembled embossing plate according to the present invention, comprising the components of Figures 1 to 4; Figure 6 is an enlarged rear perspective view of a detail of a partially assembled embossing plate according to the present invention comprising the components of Figures 1 to 4; and Figure 7 is an enlarged front perspective view of a detail of the partially 20 assembled embossing plate of Figure 6.

Referring first to Figure 1, there is shown a first sheet 10, constituting a first component of a preferred embodiment of embossing plate according to the present invention. The sheet 10 is formed from steel, with an unmachined thickness y of 0.2mm. The front face 11 of the sheet 10 is visible in Figure 1, and it can be seen that this has a plurality of holes 12, which have been machined through the sheet 10. As -9 -can be seen, the holes 12 are arranged in clusters of four, in a square configuration, and arranged at spaced locations 13 across the sheet 10, corresponding to a specific desired embossing pattern. The holes 12 have a diameter of 2mm.

Referring now to Figure 2, there is shown the rear face 14 of the first sheet 10.

In the rear face 14 are formed, by machining, a plurality of square recesses 15, at the spaced locations 13 referred to with reference to Figure 1 above. An enlarged view of one such recess is shown in Figure 3. As can be seen, the holes 12 machined through the sheet 10 are located centrally within each recess 15. Each recess 15 has dimensions of lOmm x 10mm square, and a depth x of 0.1mm, i.e. half the unmachined thickness y of the sheet 10.

Each recess 15 is adapted to receive a panel 16 as shown in Figure 4. Each panel 16 is machined from a second sheet of stainless steel, having an unmachined thickness of 1.5mm. Each panel 16 has a base 17 with four raised projections 18 extending therefrom. The panel 16 has dimensions of lOmm x lOmm square, and the base 17 has a thickness z of 0.1mm, i.e. equal to the depth x of the recesses 15 in the first sheet 10. The projections 18 are located centrally within the panel 16 and arranged in a square configuration corresponding to that of the holes 12 in the first sheet 10. The projections 18 are formed with domed tops, and have a height w above the base 17 of 1.3mm, i.e. greater than the difference between the unmachined thickness y of the first sheet 10 and the depth x of the recesses 15 (or the thickness z of the base 17).

As such, when the panels 16 are mounted in the recesses 15, to form an embossing plate 20, as shown in Figure 5, the raised projections 18 protrude through the holes 12 to stand proud of the front face 10 thereof Figure 5 shows a view of the -10 -entire embossing plate 20, from which the repeating pattern of spaced locations 13 for each group of projections 18 can be appreciated.

Referring now to Figure 6, this shows a detail of the rear face 14 of a partially assembled embossing plate 20, with some, but not all, of the recesses 15 having a panel 16 mounted and secured therein. Where the recess 15 has not been provided with a panel 16, the holes 12 through the sheet 10 remain visible, as is the indentation of the recess 15. The other recesses 15 have been provided with panels 16, which are mounted such that the base 17 of the panel 16 engages with the recess 15, with the panel 16 then being secured to the sheet 10 by welding or taping.

Figure 7 shows the same detail of the partially assembled embossing plate 20 of Figure 6, but viewed from the front face 11. Again, for the location 13 for which the corresponding recess 15 has not been provided with a panel 16, the holes 12 machined through the sheet 10 remain visible. For the other locations 13, for which the corresponding recesses 15 have each been provided with a panel 16, it can clearly be seen that the projections 18 of the panel 16 protrude through the holes 12 to stand proud of the front face of the sheet 10.

Claims

Claims 1. A method of producing an embossing plate, comprising the steps of: (i) in a first sheet of material, forming at least one recess over a portion of the area of said first sheet and at one or more pre-determined locations corresponding 5 to a desired embossing pattern; (H) forming one or more holes through the first sheet, in the or each recess, said holes being arranged in a configuration corresponding to said desired embossing pattern; (Hi) from a second sheet of material, forming at least one panel having a base with dimensions corresponding to those of the or each recess, and further comprising one or more raised projections extending from the base, said projections being complementary to the holes, and arranged in a configuration corresponding to said desired embossing pattern; (iv) mounting the or each panel in the or each recess, such that the raised projections protrude through the holes; and (v) securing the or each panel in place in the or each recess.
2. A method as claimed in claim 1, wherein the first sheet and the second sheet are both formed from steel.
3. A method as claimed in claim 1 or claim 2, wherein in step (i) the or each recess is formed by a machining process.
4. A method as claimed in any of the preceding claims, wherein in step (i) the or each recess is formed such that the depth x of the or each recess is substantially half of the thickness y of the first sheet over the remainder of its area.
5. A method as claimed in any of the preceding claims, wherein in step (H) the one or more holes are formed by a machining process.
-12 - 6 A method as claimed in any of the preceding claims, wherein in step (iii) the or each panel and its raised projections are formed by a machining process.
7. A method as claimed in any of the preceding claims, wherein in step (iii) the or each panel is formed such that the thickness z of the base is substantially equal to the depth x of the or each recess, and wherein the height w of the raised projections above the base is substantially greater than (y-x) where y is the thickness of the first sheet over its unrecessed area.
8. A method as claimed in any of the preceding claims, wherein in step (v) the or each panel is secured in the or each recess by a process selected from welding or 10 taping.
9. A method as claimed in any of the preceding claims, wherein in step (i) a plurality of recesses are formed at spaced locations across the first sheet, and wherein in step (Hi) a plurality of corresponding panels are formed.
10. An embossing plate comprising: (a) a first sheet of material, having at least one recess formed therein over a portion of the area of said first sheet, the or each recess having formed therein one or more holes extending through the first sheet, said holes being arranged in a configuration corresponding to a desired embossing pattern; and (b) at least one panel formed from a second sheet of material, the or each panel having a base with dimensions corresponding to those of the or each recess, and further comprising one or more raised projections extending from the base, said projections being complementary to the holes, and arranged in a configuration corresponding to said desired embossing pattern; and wherein the or each panel is mounted and secured in the or each recess, such that the raised projections protrude through the holes.
-13 - 11. An embossing plate as claimed in claim 10, wherein the first sheet and the second sheet are both formed from steel.
12. An embossing plate as claimed in claim 10 or claim 11, wherein the depth x of the or each recess is substantially half of the thickness y of the first sheet over the remainder of its area.
13. An embossing plate as claimed in any of claims 10 to 12, wherein the thickness z of the base of the panel is substantially equal to the depth x of the or each recess, and wherein the height w of the raised projections above the base is substantially greater than (y-x) where y is the thickness of the first sheet over its unrecessed area.
14. An embossing plate as claimed in any of claims 10 to 13, wherein the or each panel is welded or taped in the or each recess.
15. An embossing plate as claimed in any of claims 10 to 14, comprising a plurality of recesses formed at spaced locations across the first sheet, and a plurality of corresponding panels engaged therewith.
16. An embossing plate produced by a method as claimed in any of claims 1 to 9.
17. Embossing apparatus incorporating an embossing plate as claimed in any of claims 10 to 16.