Patent Description:
A die is a specialized tool used in manufacturing industries to cut, bend and/or shape materials mostly using a press. Like molds, dies are generally customized to the item they are used to create. Products made with dies range from simple paper clips or carton boxes to complex pieces used in advanced technology. Forming dies is typically performed by die makers and put into production after mounting into a press.

Steel-rule die, also known as steel-rule cutting dies, are used for cutting and/or shaping sheets of materials comprising plastics, cork, felt, fabrics, cartons and paperboard. The cutting surface of the die is the edge of hardened steel strips, known as steel rule or merely as "rule" hereinafter. Grooves are made with a saw or laser-cut in wooden or plywood board to position the rules. These groves are also known as "kerfs". The mating die can be a flat piece of hardwood or steel, a male shape that matches the workpiece profile, or it can have a matching kerf that allows the rule to nest into. Rubber strips are glued beside the rules to eject the sheet once processed.

Dies are used for cutting and also for embedding sections of carton or paper sheets, drawing lines and curves, forming cut-out sections and bending/folding lines.

<CIT> belongs to the prior art and discloses die block for a steel-rule cutting die, the die block comprising at least one kerf perpendicularly extending from an upper surface to a bottom surface of the die block, each kerf being configured to receive a corresponding steel-rule intended to be partially inserted into the kerf and a magnetic retention device. However, <CIT> relies on big and bulky, and thus, very heavy magnets which represents a considerable disadvantage.

The following detailed drawbacks may be associated with steel-rule cutting dies known in the art.

In general, kerfs have to be a little "tight", meaning for example, for a <NUM> (<NUM> inch) thick rule, the corresponding kerf meant to receive the rule should be about <NUM> or <NUM> (<NUM>" or <NUM>") large, for a press-fitted/tight fit. This has the disadvantage that when the die expands, the rule may become loose creating instability, which is very undesirable. In contrast, should the die be made during winter time, the rule will have a tendency to "expand" during summer time (i.e. "outward pressure"), which would force the resulting die to expand as well, which would adversely affect the corresponding pattern to be respected by the die, which is also very undesirable, for obvious reasons. Therefore, traditional dies, and their corresponding components thereof, such as rules and corresponding kerfs intended to receive them, are highly sensitive to variations in temperature, humidity level, etc. Also, due to, the die has to be frequently re-knifed. The sheet production has to be stopped to be re-knifed by changing the rules.

Another drawback is associated with fact in that a die block and the rules must be stable and perfectly horizontally aligned once installed into the press to assure uniform cutting or bending over the all surface of the processed sheet. Traditional cutting dies have to be constantly levelled on press before starting the press for production. Here again, such leveling is time consuming and as the press needs to be frequently stopped.

Thus, it would be particularly useful to provide an improved system which, by virtue of its design and components, would be able to overcome or at least minimize some of the known drawbacks associated with conventional systems.

The aforesaid and other objectives of the present invention are realized by generally providing a die block for steel-rule cutting die and a steel-rule cutting die assembly comprising the same.

The invention is first directed to a die block comprising:.

According to a preferred embodiment, each kerf defines a kerf width and each corresponding rule has a rule thickness, the kerf width being equal or greater than the rule thickness.

According to a preferred embodiment, each kerf comprises at least two vertical facing walls extending from the upper to the bottom surface of the die block, and wherein the at least one magnetic element defines at least one flat surface parallel to one of the vertical facing wall of each kerf optionally forming a gap between the flat surface of each magnetic element and the wall's surface of each kerf. Preferably, the flat surface of each magnetic element is substantially aligned with the wall of each corresponding kerf to be in continuity with the kerf's wall.

According to a preferred embodiment, the die block further comprises: a plurality of spaced apart kerfs, extending from the upper to the bottom surface of the die block, along a longitudinal axis, each of the spaced apart kerfs being configured to receive a corresponding shaped steel-rule; and a channel extending from the upper to the bottom surface of the die block along the longitudinal axis, the channel being configured to receive and maintain into the die block a spacer plate comprising a ferromagnetic material. The at least one magnetic element magnetizes the spacer plate for magnetically interacting with each of the shaped steel-rules once inserted into the corresponding spaced apart kerfs. Preferably, each of the spaced apart kerfs may a V-shaped kerf having a first vertical face extending away from the longitudinal axis in a same direction than a subsequent V-shaped kerf, and a second vertical face parallely extending to the longitudinal axis and being adjacent to the channel.

According to a preferred embodiment, the at least one magnetic element is located in a recess extending from the kerf.

According to a preferred embodiment, the die block is a foam layer comprising said at least one kerf and said at least one magnetic element, the die block further comprising: a bottom plate configured to hold and support the foam layer, and comprising a plurality of grooves matching the at least one kerf of the foam layer for receiving a proximal end of the corresponding at least one steel-rule; and an opposite top plate comprising a plurality of grooves matching the at least one kerf of the foam layer for also receiving the corresponding at least one steel-rule with the knife of each steel-rule extending outwardly from the top plate. The bottom and top plates conceal the at least one magnetic element located into the foam layer. Preferably, the foam layer may comprise polyurethane, and the bottom plate and top plate may comprise a fiberglass material.

According to a preferred embodiment, each of the at least one magnetic element is a magnet. As described herein after, other magnetic elements could be considered without departing of the present invention.

The invention is also directed to a cutting die assembly for cutting and/or punching a material sheet using a press. The cutting die assembly comprises:.

According to a preferred embodiment, each kerf of the assembly may define a kerf width and each corresponding rule has a rule thickness, the kerf width being equal or greater than the rule thickness.

According to a preferred embodiment, each kerf of the assembly may comprise at least two vertical facing walls extending from the upper to the bottom surface of the die block, and wherein the at least one magnetic element defines at least one flat surface parallel to one of the vertical facing walls of each kerf for optionally forming a gap between each flat surface of each magnetic element and each wall's surface of each kerf. Preferably, the flat surface of each magnetic element is substantially aligned with the wall of each corresponding kerf to be in continuity with the kerf's wall.

According to a preferred embodiment, the cutting die assembly may further comprises: a plurality of spaced apart kerfs, extending from the upper to the bottom surface of the die block, along a longitudinal axis, each of the spaced apart kerfs being configured to receive a corresponding shaped steel-rule; a channel extending from the upper to the bottom surface of the die block along the longitudinal axis; and a spacer plate comprising a ferromagnetic material and inserted into the channel configured to receive and maintain said spacer into the die block. The at least one magnetic element magnetizes the spacer plate for magnetically interacting with each of the shaped steel-rules once inserted into the corresponding spaced apart kerfs. Preferably, each of the spaced apart kerfs is a V-shaped kerf having a first vertical face extending away from the longitudinal axis in a same direction than a subsequent V-shaped kerf, and a second vertical face parallely extending to the longitudinal axis and being adjacent to the channel.

According to a preferred embodiment, the at least one magnetic element of the cutting die assembly is located in a recess extending from the kerf.

According to a preferred embodiment, the die block of the cutting die assembly is a foam layer comprising said at least one kerf and said at least one magnetic element, The cutting die assembly further comprises: a bottom plate configured to hold and support the foam layer, and comprising a plurality of grooves matching the at least one kerf of the foam layer for receiving a proximal end of the corresponding at least one steel-rule; and a top plate opposite to the bottom plate comprising a plurality of grooves matching the at least one kerf of the foam layer for also receiving the corresponding at least one steel-rule with the knife of each steel-rule extending outwardly from the top plate. The bottom and top plates conceal the at least one magnetic element located into the foam layer. Preferably, the foam layer comprises polyurethane, and the top and bottom plates comprise a fiberglass composite material. Other light resisting foam and composite materials known in the art can be used without departing from the instant invention.

According to a preferred embodiment, the at least one magnetic element of the cutting die assembly may be a magnet.

The magnetic device(s) located in proximity to the kerf(s) may allow maintaining the corresponding rule(s) in position within its kerf even if the kerf is cut "loosely", that is to say with a corresponding kerf having a certain margin, so that the corresponding rule may be quickly and easily inserted and accurately maintained even if the die block expand or retract under atmospheric variations.

Other advantages will be described herein after.

The above and other objects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawings in which:.

Preferred embodiments of steel-rule cutting die assembly for cutting and/or shaping sheet metal and softer materials, such as plastics, wood, cork, felt, fabrics, and paperboard are now described. Although the invention is described in terms of specific illustrative embodiment(s), it is to be understood that the embodiment(s) described herein are by way of examples only and that the scope of the invention is not intended to be limited thereby.

By the term "about" used in the instant application, it is meant that the value or data associated with this term (such as a length, weight, temperature, etc.) can vary within a certain range depending on the margin of error of the method or device used to evaluate or measure such value or data. A margin or variation of up to <NUM>% is typically accepted to be encompassed by the term "about".

"Die block" refers to the main part of the die that all the other parts are attached to.

"Steel-rule", also named "rule", is a hard steel strip of the cutting die. The rule may be in one longitudinal or curved section, or comprise several longitudinal and/or curved sections to provide customized cut or punching to the sheet.

The "knife" is the cutting or punching edge of the steel rules that can be sharp for cutting or soft for punching or bending the sheet.

The "kerf" is a longitudinal aperture or groove made with a saw or laser-cut in wooden, plywood, foam or plastic board or block to position the rules into the board or block.

Presses for cutting and or shaping sheet material such as paper, paperboard, cardboard and the like, are well known. Sheet material is typically pre-cut, and often includes pre-cut portions, which need to be stripped out using stripping stations and/or devices. Examples of mechanical devices for stripping waste from a pre-cut sheet of material are described in Applicant's <CIT>), or international patent application no.

<FIG> illustrate portions of a die block <NUM> in accordance with a first embodiment. A die block <NUM> typically comprises at least one kerf <NUM> perpendicularly extending from an upper surface <NUM> to a bottom surface <NUM> of the die block <NUM>. Each kerf is configured to receive a corresponding steel-rule <NUM> intended to be partially inserted into the kerf as shown on <FIG>. The section of the rule <NUM> that outwardly extends from the upper surface <NUM> of the block <NUM> has a distal edge known as the knife <NUM> for cutting, if the knife is sharp, or punching the sheet, if the knife is soft.

As partially illustrated on <FIG>, a die block will generally comprise a plurality of rules <NUM> and corresponding kerfs <NUM> forming a more or less complex design or pattern for producing different customized material sheets.

The making of a packaging box is an example in which a sheet of paperboard or carton will be cut and punched to form different sections that will be afterwards bent and glued to form the box. To access inside the box, at least one of its faces will need to have pre-defined cuts to allow an easy opening of the box and also to close the box between after opening. Accordingly, the die box is engineered to comprise both sharp and soft knifes <NUM> for producing the required box after bending and gluing.

From the above example, one may understand that a die block has to be horizontal when installed into the press with all the rules horizontally aligned over the entire surface of the die block to evenly process each sheet entering the press. A variation of the horizontality of the die block and/or of the alignment of the rules will make the processed sheet improper to use and the press will have to be stopped for leveling the die block and rules.

The die block <NUM> disclosed here allows avoiding that the expansion/contraction of the block under atmospheric variations affects the rules alignment. To do so, the die block also comprises at least one magnetic element <NUM> located in proximity to each kerf <NUM> for providing a magnetic field that retains the steel-rule <NUM> when the steel-rule is received into the corresponding kerf. Although the magnetic element described in the drawings is a magnet, other options may considered without departing from the scope of then present invention, such as electro-magnetic systems.

According to a preferred embodiment, such as the one illustrated on <FIG>, each kerf <NUM> defines a kerf width <NUM> and each corresponding rule has a rule thickness <NUM>. Preferably, the presence of one or more magnetic elements <NUM> along the kerf <NUM> stabilizes the rule <NUM> inserted into the block <NUM>, allowing the kerf to have its width <NUM> at least equals to the rule's thickness <NUM> as illustrated on <FIG>, or the kerf's width <NUM> slightly greater than the rule's thickness <NUM> as illustrated on <FIG>. This new configuration of the die block will diminish the influence of die block expansion due to the variations of the atmospheric conditions (temperature, humidity, pressure) on the rule's alignment.

As illustrated on <FIG> or <FIG>, each kerf <NUM> generally comprises at least two vertical facing walls <NUM>, <NUM> extending from the upper <NUM> to the bottom <NUM> surface of the die block <NUM>. The magnetic element <NUM> adjacent to one of the kerf's walls <NUM> defines at least one flat surface <NUM> parallel to one of the vertical kerf's walls.

As illustrated on <FIG> and <FIG>, each kerf <NUM> may have several sub-sections <NUM> for one rule <NUM> presenting corresponding sub-sections <NUM> to be inserted into the kerf <NUM>. The die block <NUM> may have several magnetic elements <NUM> disposed along the kerf and be located according to different position (see <FIG>). The number and position of each magnetic element will be selected in accordance with the size, shape and weight of each rule.

As illustrated in <FIG> and <FIG>, the flat surface <NUM> of each magnetic element may substantially aligned with the wall of each corresponding kerf to be in continuity with the kerf's wall. The steel-rule <NUM> once inserted into the kerf is preferably not directly in contact with the magnetic element <NUM> while being very close. A distance or gap of between about <NUM> and <NUM>, more preferably of about <NUM> (or <NUM>") between the magnetic element and the rule's surface is acceptable.

As illustrated in <FIG>, the magnetic elements may also be kept apart from the rule <NUM> by concealing the magnetic element <NUM> into the die block <NUM> to form a gap <NUM> between the flat surface <NUM> of each magnetic element <NUM> and the wall's surface <NUM> of each kerf <NUM>. As aforesaid, the gap <NUM> may be between about <NUM> and <NUM>, more preferably the gap is about <NUM> (or <NUM>"). <FIG> and corresponding <FIG> illustrate three examples of possible configurations for concealing a magnetic element <NUM> having a longitudinal trapezoid shape with the smaller face <NUM> adjacent to the kerf. This specific form of the magnetic element can be easily retained into the die block using different options of embedding or entrapping volumes <NUM> (<FIG> and <FIG>) for entrapping/embedding each magnetic element <NUM> and maintaining it slightly apart from the kerf <NUM> and the corresponding rule <NUM>. Other shapes for the magnetic elements and corresponding insert or entrapping volumes <NUM> can be considered without departing from the scope of the present invention.

The Figures illustrate magnetic elements that are not extending all along the entire thickness of the die block <NUM>. Other configurations can be considered without departing from the scope of the present invention, for instance with a magnetic element that would extend from the upper <NUM> to the bottom <NUM> surface of the die block <NUM>.

As illustrated on the Figures, the die block <NUM> may comprise a foam layer <NUM> in which the kerfs have been cut together with the entrapping volumes <NUM> of the magnetic elements. The die block <NUM> may further comprising a bottom plate <NUM> configured to hold and support the foam layer <NUM> and an opposite top plate <NUM> comprising a plurality of grooves <NUM> matching the kerf(s) of the foam layer <NUM> for also receiving the corresponding steel-rule(s) with the knife of each steel-rule extending outwardly from the top plate <NUM>. The bottom plate <NUM> and the top plate <NUM> conceal the magnetic element(s) located into the foam layer <NUM>. Preferably, the foam layer may be made of a rigid foam block comprising for instance polyurethane, and the bottom plate and top plate may comprise a hard plastic material.

Referring to the example of the making of a packaging box mentioned herein before, one may understand that a die block may further comprise specific steel-rule/kerf arrangements for instance for producing specific cuts allowing the opening of the box (see <FIG> illustrating an arrangement for producing a large V-shaped opening generally located on the top a box).

An example of such specific arrangement is illustrated on <FIG>. It is understood that one die block may comprises a plurality of different arrangements in accordance with the final design of the punched/cut sheet.

The die block <NUM> comprises a plurality of spaced apart kerfs <NUM> extending from the upper <NUM> to the bottom surface <NUM> of the die block <NUM>, along a longitudinal axis (X-X'). Each of the spaced apart kerfs <NUM> is configured to receive a corresponding shaped steel-rule <NUM>. The die block also comprises a channel <NUM> extending from the upper <NUM> to the bottom <NUM> surface of the die block <NUM> along the longitudinal axis (X-X'). The channel <NUM> is configured to receive and maintain into the die block <NUM> a spacer plate <NUM> comprising a ferromagnetic material. The magnetic element <NUM> magnetizes the spacer plate <NUM> allowing the magnetized plate to magnetically interact with each of the steel-rule plates <NUM> in the spaced apart corresponding kerfs <NUM>. In other words, the presence of the magnetized plate along the axis X-X' formed by the kerfs allows using a smaller number of magnetic elements <NUM> along the same axis while interacting with all the rules <NUM> present along the magnetized plate <NUM>.

As illustrated in the Figures, the spaced apart kerfs <NUM> may have a V-shape defining a first vertical face <NUM> extending away from the longitudinal axis in a same direction than a subsequent V-shaped kerf, and a second vertical face <NUM> parallely extending to the longitudinal axis and being adjacent to the channel <NUM>.

As described herein before, each magnetic element <NUM> may be located into a recess or entrapping volume <NUM> extending from the kerf <NUM> when no magnetizing plate is used, or extending from the channel <NUM> when a magnetizing plate is used as illustrated on <FIG> and <FIG>. Each of the at least one magnetic element may be a magnet or other magnetic or electro-magnetic elements known in the art.

<FIG> illustrates an arrangement for producing a large V-shaped opening, generally located on the top a box. This arrangement comprises two converging axes of spaced-apart V-spaced rules as detailed above and a U-shaped rule <NUM> located at the converging point of two axes. The U-shaped rule <NUM> will form a cut in the sheet of material that will be used in collaboration with the cuts formed by the converging V-shaped rules to manually strip off the V-shaped opening and open the box. It has to be understood that other kerf/rule arrangement can be designed without departing from the scope of the invention.

As illustrated on <FIG>, the magnetic element <NUM> may also be located at the opposite ends <NUM> of the kerf <NUM> for facing the distal lateral ends <NUM> of the rule <NUM>. As better shown on Figure 2C, this location of the magnetic elements <NUM> is particularly convenient when, for instance, the kerf <NUM> is closely extending along the periphery or edge <NUM> of the die block <NUM>. As such, there is not enough space between the kerf <NUM> and the edge <NUM> to nest a magnetic element <NUM> there between. As better shown on Figures 2A or <FIG>, the flat surface <NUM> of the magnetic elements <NUM> may be optionally in contact with the distal end <NUM> of the rule <NUM>.

As illustrated in <FIG>, also in reference with the description of <FIG> detailed above, the invention is also directed to a cutting die assembly <NUM> for cutting and/or punching a material sheet using a press. The cutting die assembly <NUM> may comprise:.

The cutting die assembly may contain all the other elements as described herein before for the die block, and additional elements known in the art for the manufacturing of cutting-dies.

Magnets: The force of a magnet is commonly defined by a number. Higher the number is, stronger is the magnet. However, the higher the number is, more brittle the magnet becomes. The most common grades of Neodymium (Rare earth) magnets are N35, N38, N40, N42, N45, N48, N50, N52, and N55. Any one of these strengths can be used. More preferably, N52 magnets are used.

Foam: Although any non-porous stable material can be used for this application, preferably the applicant uses a light weight 301b low density polyurethane board that also provides optimal dimensional stability and is used for the core (the foam layer) of the die.

Top & bottom plates: There are many materials that can be used for the top and bottom plates. Preferably, a high-pressure fiberglass laminate G10 is used. Such a resin-based laminate is strong, extremely stable, and is very well cut with a laser.

Rules: The body of the cutting rule usually has a hardness of about <NUM> - <NUM> Rockwell and the cutting bevel has a hardness of <NUM> - <NUM> Rockwell. The body is softer so it can be bent to the desired shape needed. The bevel is much harder because the plate that is cuts the material against is also <NUM>- <NUM> Rockwell. The full body of the Creasing rule is <NUM> - <NUM> Rockwell. It is softer because all it is used for is to mark the material for where it has to fold.

The die block or the cutting-die assembly according to the present invention may be provided as a kit of elements to be assembled, optionally comprising instructions for assembling the elements. The instructions can also be presented as a plan or map indicating the position of each elements to be assembled.

As illustrated on <FIG>, the invention is further directed to a method for providing stability and alignment of a die block intended to be used in collaboration with a press for cutting and/or punching a sheet of material. The method comprises the steps of:.

As illustrated on <FIG>, the invention is yet further directed to a method for manufacturing a stabilized die block intended to be used in collaboration with a press for cutting and/or punching a sheet of material. The method comprises at least the following steps:.

On a standard wood die, the cutting and creasing rules are held in tightly to keep it from falling out while the cutting-die is being run. This is very important since the die is run upside down in most auto-platen die cutting machines at speeds of up to <NUM>,<NUM> sheets per hour. Therefore, in order to keep the rule from falling out, the kerf was previously laser cut at around <NUM> - <NUM>" (<NUM> - <NUM>) and the cutting or creasing has an exact width of <NUM>" (<NUM>). Although this does not seem like a big difference, it can give quite a large expansion on the die. The more linear inches / meters of rule on the job, the more the die will expand. A die can expand as much as <NUM>" (<NUM>) which is completely unacceptable with today's standards of modern machinery. The maximum allowable when die cutting with a steel counter plate is <NUM>" (<NUM>). Also with weather wood can expand and contract which also affects dimensional stability. During dry season (winter/ spring) the wood dries and the die can shrink slightly and also can make some of the rules loose thus allowing them to fall out of the die during a run with can cause big damage to the machine. During the (Summer/Fall) the die can swell from humidity and expand the size of the die. The magnetic device(s) located in proximity to the kerf(s) allow maintaining the corresponding rule(s) in position within its kerf even if the kerf is cut "loosely", that is to say with a corresponding kerf having a certain margin, so that the corresponding rule may be quickly and easily inserted and accurately maintained even if the die block expand or retract under atmospheric variations.

Self leveling: The present invention also allows reducing the number of times the cutting-die assembly needs to be re-ruled or re-knifed. Indeed, the presence of the magnetic element allows faster leveling of the die block on press. As explained above, a die is laser cut tighter when cut on wood. Because the die is cut tighter, it holds the rule tighter in the die, and as such does not allow the cutting rule to self-level. Since the rule cannot self-level, it becomes damaged faster and decreases the life of the die. Wood dies are rarely ever re-ruled because of the time needed for them and their loss of precision. So they are disposed (adding to land fill) and a new one is ordered. With the present invention (named Phantom™ Die by the Applicant), all of these problems are eliminated because the rules are held in position with the magnetic elements and the die is laser cut looser, for instance to about <NUM>" (<NUM>) giving the rule to sit properly on the press. The Phantom™ die also easily re-rules and always maintains stability. Also, because the die according to the present invention can be re-ruled easily all the changed metal rule may be recycled.

Also, by magnetizing the die block, the cutting-die assembly will have a better stability once inserted into the press due to the interaction between the magnetic elements concealed into the die block, and the structural elements of the press generally comprising ferromagnetic materials (iron).

Claim 1:
A die block (<NUM>) for a steel-rule cutting die, the die block (<NUM>) comprising:
at least one kerf (<NUM>) perpendicularly extending from an upper surface (<NUM>) to a bottom surface (<NUM>) of the die block (<NUM>), each kerf (<NUM>) being configured to receive a corresponding steel-rule (<NUM>) intended to be partially inserted into the kerf (<NUM>); and
at least one element (<NUM>) having magnetic properties and being located in proximity to each kerf (<NUM>) for providing a magnetic field that retains the steel-rule (<NUM>) when the steel-rule (<NUM>) is received into the corresponding kerf (<NUM>);
the die block (<NUM>) being characterized in that the die block (<NUM>) is a foam layer (<NUM>) comprising said at least one kerf (<NUM>) and said at least one magnetic element (<NUM>), and in that the die block (<NUM>) further comprises:
a bottom plate (<NUM>) configured to hold and support the foam layer (<NUM>), and comprising a plurality of grooves (<NUM>) matching the at least one kerf (<NUM>) of the foam layer (<NUM>) for receiving a proximal end of the corresponding at least one steel-rule (<NUM>); and
an opposite top plate (<NUM>) comprising a plurality of grooves (<NUM>) matching the at least one kerf (<NUM>) of the foam layer (<NUM>) for also receiving the corresponding at least one steel-rule (<NUM>) with the knife (<NUM>) of each steel-rule (<NUM>) extending outwardly from the top plate (<NUM>); and
wherein the bottom plate (<NUM>) and the top plate (<NUM>) conceal the at least one magnetic element (<NUM>) located into the foam layer (<NUM>).