Die cutter blanket for counter-die of rotary die cutting machine, and method for manufacturing the same

Abstract

A die cutter blanket for a counter-die of a rotary die cutting machine has a cover that surrounds the counter-die forming a cylindrical sleeve around the counter-die. The cover is made from a first material having a first hardness value. The cover has a key adapted to fit into a slot of the counter-die in order to fix the cover around the counter-die. The die cutter blanket also includes a bar made from a second material having a hardness value greater than the first hardness value, which is disposed entirely inside the key, axially along the length of the key. The bar is peripherally coated by the first material.

Claims

1. A die cutter blanket for a counter-die of a rotary die cutting machine, the die cutter blanket comprising: a cover adapted to form a cylindrical sleeve around a counter-die of a rotary die cutting machine and to surround the counter-die, the cover comprising a key projecting from an inner surface of the cover, the key having a shape adapted to fit into a slot of the counter-die in order to fix the cover in place around the counter-die, the cover comprising a first material having a first hardness value; and at least one inner bar comprising a second material having a second hardness value greater than the first hardness value, wherein all of the second material is disposed inside the key in an axial direction along a length of the key, the at least one inner bar being peripherally coated by the first material of the cover.

2. The die cutter blanket according to claim 1, wherein the at least one inner bar has a hardness value greater than 50 ShD.

3. The die cutter blanket according to claim 1, wherein the cover is made of polyurethane.

4. The die cutter blanket of claim 1, further comprising: a first key comprising the first material; a first inner bar disposed within the first key, the first inner bar comprising the second material; a second key comprising the first material; and a second inner bar disposed within the second key, the second inner bar comprising the second material.

5. The die cutter blanket according to claim 4, wherein: the first key and the second key are aligned along a first longitudinal direction of the first and second keys; and the first inner bar and the second inner bar are aligned along a second longitudinal direction of the first and second inner bars.

6. The die cutter blanket according to claim 4, wherein the cover comprises a first end and a second end, a first plurality of first fingers disposed at the first end, and a second plurality of second fingers disposed at the second end, wherein the first plurality of first fingers are adapted to engage with the second plurality of second fingers to form a jig-saw joint in the die cutter blanket.

7. The die cutter blanket according to claim 6, wherein the first and second fingers divide the first and second keys and the first and second inner bars.

8. The die cutter blanket according to claim 6, wherein each first finger each second finger comprises a first lateral side, a second lateral side, and a front part.

9. The die cutter blanket according to claim 7, wherein the first and second lateral sides form an angle between 70 and 85 with a longitudinal axis of the cover.

10. The die cutter blanket according to claim 6, wherein each first finger and each second finger comprises a front part having an arrowhead shape comprising a first straight portion and a second straight portion, the first and second straight portions being joined at a vertex and forming an angle between 120 and 170.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Next, in order to facilitate the comprehension of the invention, in an illustrative rather than limitative manner an embodiment of the invention with reference to a series of figures shall be made below.

(2) FIG. 1 shows a schematic section view of a blanket known in the prior art.

(3) FIG. 2 is a schematic front view of one end of a blanket known in the prior art showing the fingers of the joining system.

(4) FIG. 3 shows a schematic section view of another blanket known in the prior art, with a key made of a material harder than the counter-die surface.

(5) FIG. 4 shows an overall schematic view of the ends of the blanket of FIG. 3.

(6) FIGS. 5a, 5b and 5c show schematically different conventional joining systems known in the prior art for the joint of the ends of the blankets to form the cylindrical sleeve wrapping the counter-die.

(7) FIG. 6 shows a schematic section view of a blanket according the present invention.

(8) FIGS. 7a and 7b show an overall schematic view of the ends of the blanket of FIG. 6, FIG. 7a showing the ends of the blanket in an open finger position, and FIG. 7b showing the ends of the blanket in a closed finger position.

(9) FIG. 8 shows a inner bar inserted in the slot of a mould, before vulcanized with soft material, according to the present invention.

(10) FIG. 9 shows a schematic front view of one end of a blanket with the typical position of the inner bar inside the fingers with straight section.

(11) FIG. 10 shows schematically a joining system for the joint of the ends of the blankets to form the cylindrical sleeve wrapping the counter-die, according a preferred embodiment of the present invention.

(12) FIG. 11 shows in detail the fingers of the joining system of the embodiment of FIG. 10.

(13) These figures refer to the following set of elements: 1. counter-die of the rotary die cutting machine 2. die cutter blanket 3. cover of the die cutter blanket 4. key of the cover of the die cutter blanket 5. slot of the counter-die 6. inner bar inserted inside the key of the die cutter blanket 7. ends of the die cutter blanket 8. fingers at both ends of the die cutter blanket 9. lateral sides of the fingers 10. front part of the fingers 11. straight two portions of the front part of the fingers 12. vertex of the front part of the fingers b. angle between the two straight portions of the front part of the finger a. angle of the lateral sides of the finger with the longitudinal axis of the cover

DETAILED DESCRIPTION OF THE INVENTION

(14) The object of the present invention is a die cutter blanket for counter-die of rotary die cutting machine.

(15) As shown in the figures, the die cutter blanket has a cover 3 that wraps the counter-die 1 forming a cylindrical sleeve around said counter-die 1. The cover is made of a soft material, preferably polyurethane.

(16) The cover 3 comprises in turn a key 4 which is insertable into a slot 5 of the counter-die 1 for the fixing thereof around said counter-die 1.

(17) The die cutter blanket comprises at least an inner bar 6 inserted inside the key 3 axially along its entire length, although according different embodiments of the invention, the inner bar 6 could be divided in several parts, or there could be more than one inner bar 6. As shown in FIGS. 6, 7a, 7b and 8, the dimensions of the section of the inner bar 6 fits the geometry of the slot 4, being the inner bar 6 peripherally coated by the cover 3.

(18) The inner bar 6 has higher hardness than the cover 3, and particularly, the inner bar 6 has a hardness close to the counter die 1 on which it lies, and unlike prior art covers with metal key does not need external elements to fix the cover to the cylinder. So, an improvement on accuracy processing cardboard is achieved. According a preferred embodiment of the invention, the hardness of the inner bar 6 is up above 50 ShD, whereas that the hardness of the cover 3 is comprised between 85-95 ShA.

(19) Preferably, for the most common key dimensions, a 0.5 mm thickness of coating material of lower hardness around the inner bar 6 is enough to ensure correct installation and ensure the functionality of the bar 6.

(20) With accord to a particular embodiment of the invention, and regarding the joint of the ends 7 of the cover 3 to form the cylindrical sleeve around the counter-die 1, the cover 3 comprises at each end 7 thereof a plurality of fingers 8 engageable with the fingers 8 of the other end 7, which provides a jig-saw joint of both ends 7 of the die cutter blanket 2.

(21) Particularly, and as it can be seen at FIGS. 10 and 11, the fingers 8 of the ends 7 of the cover have two lateral sides 9 and a front part 10, and according to a preferred embodiment, the front part 10 of the fingers 8 is arrowhead-shaped comprising two straight portions joined at a vertex 12, in such a way that they form an angle b comprised between 120 and 170. These angles b are designed to avoid cutting, scoring or void cutting of axial direction blades, as usual in the cardboard processing. Values too big would reduce the desired effect, and values too small would greatly increase the finger 8 length and worsen the quality of the joint, since the fingers would not follow the curvature of the counter-die 1 (the longer the finger, the worse quality).

(22) Preferably, the lateral sides 9 form an angle a comprised between 70 and 85 with the longitudinal axis of the cover 3, in order to adapt the geometry of the fingers 8 to the height thereof, which is defined in terms of width of the cylinder slot. This will ensure that collisions between fingers 8 are minimized, making easier the die cutter blanket 2 assembly and disassembly operations. Therefore, productivity will be increased by means of shortening cover assembly and disassembly time.

(23) Once the invention has been clearly described, it is hereby noted that the particular embodiments described above can be the subject of detail modifications as long as they do not alter the fundamental principle and the essence of the invention.