GB2285944A

GB2285944A - Die cutting device

Info

Publication number: GB2285944A
Application number: GB9501479A
Authority: GB
Inventors: Hidemaro Yamada; Toshinaga Urabe
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-01-26
Filing date: 1995-01-25
Publication date: 1995-08-02
Anticipated expiration: 2015-01-25
Also published as: CA2141116A1; GB2285944B; GB9501479D0; JPH07205342A; DE19502164A1

Description

-I- 2285944 DIE CUTTING DEVICE WITHOUT PATCH-UP SHEET

TECHNICAL FIELD OF THE INVENTION

The present invention relates to die cutting devices and more particularly to die cutting devices which do not require a patch-up sheet.

BACKGROUND OF THE INVENTION

Referring to FIG. 1, there is shown a piece of paperboard stock 1 from which a foldable paper box blank is cut using the die cutting device of FIG. 2. The blank paperboard stock 1 is inserted and impressed between the steel rule die 23 and the counterplate 31 of the die cutting device illustrated in FIG. 2. Tile solid line 12 shown in FIG. 1 indicates a cutting line where the paperboard stock 1 is cut completely through. Cutting line 12 is produced by the cutting knife 233 of steel rule die 23 piercing the paperboard stock 1 as it is impressed against the counterplate 31. The dashed line 13 of FIG. 1 indicates areas where the paperboard stock 1 has been creased (but not perforated) in order to facilitate folding of the box blank at a later stage of manufacture. The hinged folding line 13 is made by blunt creasing knife 232 of steel rule die 23 impressing the paperboard stock 1 into the female die 32 of counterplate 31. After applicati.,-,ii of the die cutting device to the paperboard stock 1, the paperboard stock 1 separates into die cutting waste 11 and product blank 14 at the cutting line 12.

In practice, it has been found to be very difficult to successfully produce a complete cutting line 12 across the entire surface of the paperboard stock 1 when the die cutting device is first assembled. The more common result is that portions of the cutting line 12 are not completely perforated through the paperboard stock 1, thereby making it impossible to separate the die cutting waste 11 from the product blank 14. Tile reason for such incomplete cutting is flat level unbalance between tile steel rule die 23 and the counterplate 31, as well as height unbalance of the cutting knives 233. Because of the relatively large surface areas of the steel rule die 23 and the counterplate 31, it is not feasible to form them perfectly flat nor to position them completely level with one another in the die cutting device. This causes the flat level unbalance. The height unbalance is caused by the gradual bending of the cutting knives 233 over the lifetime of the steel rule die 23. In order to correct for these unbalances, prior art die cutting devices require significant pre-preparation time in order to form a patch-up sheet 33 which must be placed between the counterplate 31 and the lower platen 35. The patch-up sheet 33 compensates for any unbalances between the steel rule die 23 and the counterplate 31.

The patch-up sheet 33 carries lengths of patch-up tape 34 which are glued to the upper surface of the patch-up sheet 33 at locations corresponding to the uncompleted cutting lines 12. For example, if the line section 122 of FIG. 1 were found to be not cutting completely through tile paperboard stock 1, a length of patch-up tape 34 would be positioned as shown in FIG. 2 in order to move the counterplate 31 closer to the steel rule die 23 in that area, thereby ensuring greater pressure of the cutting knife 233 against the counterplate 31. The patch-up sheet 33 is inserted between the counterplate 31 and the lower flat platen 35. Both the counter plate and the patch-up sheet 33 are fastened to the lower platen 35. The patchup tape 34 raises the counterplate 31 by any amount corresponding to the thickness of the patch-up tape 34 in order to cause the uncompleted cutting line 122 to be cut through completely. Patch-up tape 34 from 0.05 mm - 0.2 mm thickness is glued beneath the counterplate 31 which is typically 4 mm or 5 mm thick. Patch-up tape 34 is positioned under all cutting lines which were found to be uncompleted during a test impression.

The formation of the patch-up sheet 33 with the positioned pieces of patch-up tape 34 is relatively easy in the case of a simple cutting design. But a complex cutting design requires many test impressions and repeated removal of the counterplate 31 from the lower flat platen 35 in order to affix more pieces of patch-up tape 34 to the patch-up sheet 33. In a typical case, a complex cutting design requires more time for preparation of the patch-up sheet 33 than is required for actual die cutting time. After the patch-up sheet 33 has been completed and the first run of the die cutting device is completed, the patch-up sheet 33 can be removed and stored. This same patch-up sheet 33 can be used with this steel rule die 23 at the next ordered die cutting operation. However, if the steel rule die 23 is used on a 2s different die cutting machine, a completely new patch-up sheet 33 will have to be formed.

There have been attempts in the prior art to reduce the time required for creating the patch-up sheet 33. For example, Japanese Patent Publication No. HEISEI 1-56848 teaches the use of cutting knives which have bottom surfaces (i.e. the surface of the cutting knife embedded in the steel rule die 23) which are not flat. The sharpened bottom face of these cutting knives are struck into the steel plate of the chase 22 which covers the back surface of the steel rule die 23. The initial compression of the steel rule die 23 against the counterplate 31 causes the bottom surface of some of the cutting knives to deform. This deformation tends to even out the height of all of the cutting knives within the steel rule die. However, this solution requires a specially shaped cutting knife. Another prior art method to reduce the amount of time required for forming the patch-up sheet 33 is disclosed in European Patent Application No. 17179. It is disclosed therein to use an ultraviolet set plastic plate. However, as with the solution in the Japanese Patent

Publication, this requires special material to be included into the die cutting device, which requires a substantial extra cost and is therefore not economical.

There is therefore a need in the prior art for a way to eliminate the requirement for a patch-up sheet 33 from a die cutting device in such a way as to not increase the cost of the die cutting operation. The present invention is directed toward meeting those needs.

3 01 SUMMARY OF THE INVENTION

The present invention relates to a die cutting device having a sheet of resilient material, such as urethane rubber, placed between the upper and lower platens. The ability of the resilient sheet to be nonuniformly compressed acts to eliminate any unbalances between the steel rule die and the counterplate, thereby eliminating cut lines which do not completely perforate the cutting stock at certain points. Use of the present invention eliminates the preparation time previously required to prepare a patch-up sheet for each steel rule die.

In one form of the invention, a die cutting device is disclosed, comprising a die including at least one cutting knife; a counterplate; a top platen; a bottom platen; and a resilient sheet; wherein the top and bottom platens are operable to compress the die, the counterplate and the resilient sheet together, such that deformation of the resilient sheet substantially compensates for any unbalance between the at least one cutting knife and the counterplate.

In another form of the invention, a die cutting device is disclosed, comprising: cutting means; counter means; resilient means; and pressure means for applying a compressive force to the cutting means, the counter means, and the resilient means, such that material placed between the cutting means and the counter means is thereby cut; whereby compression of the resilient means substantially eliminates any unbalance between the cutting means and the counter means.

In another form of the invention, a method of die cutting material, comprising the steps of: (a) placing the material between a die having at least one cutting knife and a counterplate; (b) placing the die and the counterplate between a top platen and a bottom platen; (c) placing a resilient sheet between the top platen and the bottom platen; (d) bringing the top platen and the bottom platen together such that the die and the counterplate are compressed and the at least one cutting knife cuts through the material, wherein deformation of the resilient sheet substantially compensates for any unbalance between the die and the counterplate.

a, BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 2 is a cuttina device FIG. 1 is a plan view of a sheet of paperboard stock showing the locations of cut lines and crease lines to be formed in a die cutting operation. cross-sectional view of a prior art die showing the paperboard stock of FIG. 1 at th cross-section A-B.

FIG. 3 is a cross-sectional view of a die cutting device incorporating a first embodiment of the present invention.

FIG. 4 is a cross-sectional view of a die cutting device incorporating a second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of tile principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of tile scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would noritially occur to one skilled in the art to which the invention relates.

In the present invention, the patch-up sheet 33 is completely removed from the die cutting device and a resilient sheet, such as uretharie rubber, is inserted into the die cutting device in order to absorb the unbalances between the steel rule die 23 and tile counterplate 31. Referring to FIG. 3, there is illustrated a first embodiment of the present invention in which a resilient urethane rubber sheet 36 has been inserted between the counterplate 31 and the lower flat platen 35. The urethane rubber sheet 36 has a thickness which is preferably between 0.5 mm and 1 mm. The rubber sheet 36 is permanently fastened between the counterplate 31 and the lower flat platen 35 by means of the same screws (riot shown) which are used to fasten the counterplate 31 to the lower platen 35. The rubber sheet 36 is maintained on the die cutting device substantially permanently, requiring an investment of only one rubber sheet 36 per die cutting device, and eliminating completely the time required for forming a patch-up sheet 33 as required ill the prior art devices.

Although the theory of operation of the present invention is riot completely understood by the inventors, it is supposed 1 )t that the invention operates as follows. The rubber sheet 36 is flexible and resilient. When the steel rule die 23 is impressed against the counterplate 31, the top surfaces of the cutting knives 233 (i.e. the cutting surfaces) are impressed against the paperboard stock 1 with a high strength (from 50 tons - 120 tons). If the die cutting device is unbalanced, certain ones of the cutting knives 233 will cut through the paperboard stock 1 before other ones of the cutting knives 233 have completely cut therethrough. In the prior art die cutting devices without a patchup sheet, the.first cutting knife 233 to cut through the paperboard stock 1 and rest against the counterplate 31 would effectively stop any further compression of the steel rule die 23 toward the counterplate 31. Because of this, the cutting knives 233 which had not completely cut through the paperboard stock 1 were thereby prevented from doing so. The inclusion of the flexible rubber sheet 36 allows further compression of the steel rule die 23 toward the counterplate 31, by allowing the cutting knife which has completely cut through the paperboard stock 1 to compress the counterplate 31 into the flexible rubber sheet 36, thereby allowing further advancement of the steel rule die 23 and therefore complete cutting by all of the cutting knives 233. In other words, tile rubber sheet 36 is compressed at the locations where the cutting knives 233 first touch the counterplate 31, and thereby allow the remaining cutting knives to completely cut through the uncompleted cut areas 122.

It will be appreciated by those skilled in the art that the conventional prior art methods for creating equal relative distances between the top of the cutting knives 233 and the counterplate 31 involved adjusting a patch-up sheet 33, which requires significant pre-preparation time before the die cutting operation may commence. In other words, tile prior art method requires that the distance between the top of the cutting knives and the counterplate 31 be made equal in a static situation. By contrast, the present invention equalizes the distance between the top of the cutting knives 233 and the counterplate 31 dynamically, with every compression of the die cutting device.

The preferred embodiment of the present invention has been described as using urethane rubber for the sheet 36, but those skilled in the art will recognize that the present invention may be practiced with any suitable resilient material which can be compressed and later returned substantially to its original shape. Additionally, the preferred embodiment of the present invention is to form the flexible sheet 36 to a thickness between 0.5 mm and 1 mm. Those skilled in the art will recognize that it is possible to use different thicknesses of the material 36.

Furlhermore, the embodiment of FIG. 3 shows the flexible sheet 36 located between the counterplate 31 and the lower platen 35. Those skilled in the art will recognize that the flexible sheet 36 can be placed at arty convenient location between the platens of the cutting die. For example, F1G. 4 shows the flexible sheet 36 placed between the chase 22 and the tipper flat platen 21. The placement of the flexible sheet 36 in this location achieves substantially tile sartie effect as its placement as shown in FIG. 3. Similarly, the flexible sheet 36 could be placed between the chase 22 and the bottom of the steel rule die 23.

It will be further appreciated by those skilled in the art that the present invention may be incorporated into any die cutting device in which cutting knives counter against a counterplate. The relative orientation and movement of the two platens is not critical. For example, the present invention is equally useful ill a die cutting device having a fixed upper platen 21 arid a moveable lower platen 35, ur a die cutting device having an upright tipper platen 21 and a lower plalen 35 which swings to strike the upright tipper platen 21, which is known as a Tohmson press. Finally, the il present invention is not limited to use with the die cutting of paperboard. It will be recognized by those skilled in Lhe art that die cutting of similar products such as corrugated board and plastic sheet material will equally benefit from 5 the use of the present invention.

The present invention provides several advantages in the die cutting process. First, it raises productivity by completely removing the operation of forming the patch-up sheet. The present invention also does away with the requirement of disposable goods in the die cutting operation, such as the patch-up sheet 33, the patch-up tape 34, an(] other special materials such as specially formed knife blades. Furthermore, the resilient rubber sheet of the present invention substantially reduces the sound which is made when the cutting knife 233 strikes the counterplate 31. This allows the die cutting operation to be performed in areas which were heretofore too noise sensitive for such operations. Finally, the present invention substantially increases the operational life of the cutting knives 233 and the counterplate 31 by reducing the damage to both devices.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.

Claims

What is claimed is:

A die cutting device, comprising: a die including at least one cutting knife; a counterplate; a top platen; a bottom platen; and a resilient sheet; wherein the top and bottom platens are operable to compress the die, the counterplate and the resilient sheet together, such that deformation of the resilient sheet substantially compensates for any unbalance between the at least one cutting knife and the counterplate.
2. The die cutting device of claim 1, wherein the resilient sheet comprises a urethane rubber sheet.
3. The die cutting device of claim 2, wherein the urelliaile rubber sheet has a thickness between 0.5 mm and 1.0 RIM.
4. The die cutting device of claim 1, wherein the resilient sheet is disposed between the counterplate arid the 20 bottom platen.
5. The die cutting device of claim 1, wherein the resilient sheet is disposed between the die and the top platen.
6. The die cutting device of claim 1, further comprising 25 a chase disposed between the die and the top platen.
7. The die cutting device of claim 6, wherein the resilient sheet is disposed between the chase and the top platen.

i 1
8. The die cutting device of claim 6, wherein the resilient sheet is disposed between the chase and the die.
A die cutting device, comprising: cutting means; counter means; resilient means; and pressure means for applying a compressive force to the cutting means, the counter means, and the resilient means, such that material placed between the cutting means and the counter means is thereby cut; whereby compression of the resilient means substantially eliminates any unbalance between the cutting means and the counter means.
10. The die cutting device of claim 9, wherein the resilient means comprises a urethane rubber sheet.
11. The die cutting device of claim 10, wherein Ll-le urethane rubber sheet has a thickness between 0.5 mm and 1.0 Mm.
12. The die cutting device of claim 9, wherein the resilient means is disposed between the counter means and Ihe pressure means.
13. The die cutting device of claim 9, wherein the resilient means is disposed between the cutting means and the pressure means.
14. The die cutting device of claim 9, further comprising chase means disposed between the cutting means and the pressure means.
15. The die cutting device of claim 14, wherein the resilient means is disposed between the cilase means and the pressure means.
16. The die cutting device of claim 14, wherein the resilient means is disposed between the chase means and the cutting means.
17. A method of die cutting material, comprising the steps of:

(a) placing the material between a die having at least one cutting knife and a counterplate; (b) placing the die and the counterplate between a top platen and a bottom platen; (c) placing a resilient sheet between the top platen and the bottom platen; (d) bringing the top platen and the bottom platen together such that the die and the counterplate are compressed and the at least one cutting knife cuts through the material, wherein deformation of Ihe resilient sheet substantially compensates for any unbalance between the die and the counterplate.
18. The method of claim 17, wherein step (c) comprises placing the resilient sheet between the counterplate and the bottom platen.
19. The method of claim 17, wherein the step (c) comprises placing the resilient sheet between the die and the top platen.