A HOLDER FOR A PANEL CUTTING PLATE

Abstract: The invention relates to a cutting tool (10) and a tool holder (17) for cutting panels from blanks of sheet-like material. The cutting tool comprises a thin cutting plate (12) on which is formed by etching a cutting edge (14) having a contour corresponding to the outline of the panels to be cut out. The cutting plate also comprises a plurality of openings (16) which are surrounded by the cutting edge. The tool holder is a metallic cylinder (17) to be mounted on the drive shaft (53) of a conventional panel cutting apparatus and comprises a seat (26) for receiving the cutting plate which is retained in the seat by keys (30). In the cylinder are formed passageways communicating with a source of vacuum and also communicating with the openings on the cutting plate to create a zone of vacuum in the vicinity of the cutting edge.

Description: The present invention relates to a holder for a thin metallic cutting plate for cutting panels from sheet-like material as disclosed in the first part of claim 1, such a holder being described in US-A-4 537 588. More specifically, the present invention relates to the art of cutting panels from blanks of sheet-like material such as paper blanks for producing window envelopes. More specifically, the invention comprehends an improved cutting tool for performing the panel cutting operation and an improved holder for the cutting tool. Envelopes with a transparent panel or window for allowing a visual inspection of the enclosure are well known and widely used. Window envelopes are manufactured from a web of paper material which is initially cut into blanks having a predetermined shape. Then, a panel is cut from each blank by a panel cutting apparatus to form the window before carrying out the finishing steps of the manufacturing operation such as folding the blanks, gumming, printing and packaging. Prior art panel cutting apparatuses use a rotary cutter comprising a cutting tool in the form of a massive cutting die and a rotary die holder to bring the cutting die successively in engagement with the envelope blanks which advance in serial order on a conveyor. The die holder is a metallic cylinder mounted for rotation on a drive shaft synchronized with the conveyor so that, at each revolution of the die holder, the cutting die engages a different envelope blank. The cutting die and the die holder are provided with small passages in register with an orifice on the drive shaft which communicates through a cavity, formed in the drive shaft, with a source of vacuum. The purpose of this arrangement is to allow a localized vacuum zone to be formed in the vicinity of the cutting die in order to retain to the cutting die and carry away the panels which are cut out from the blanks. Typically, the drive shaft is provided with a plurality of orifices at different locations thereon to accept die holders of various types and sizes. The vacuum supply to each orifice is controlled by means of valves by the operator of the panel cutting apparatus who selects the orifice to which vacuum is to be applied and shuts off the vacuum to all the other orifices. On the drive shaft on which is mounted the die holder are also munted a pair of rubber rollers engaging the blanks while the cutting die cuts out the panels to maintain registration accuracy. US-A-4 537 588 discloses a cutting tool with a holder in form of a rotary cutter containing the characteristics of part 1 of the independent claims 1 and 7. More specifically, this patent describes a rotary punch device designed to make window cut-outs in envelopes and cardboards boxes. A pair of retaining segments clamp on the rotary punch a metal foil having a cutting edge etched out of the foil material. Vacuum bores in the cylindrical surface of the rotary punch communicate with a vacuum source through longitudinal condiuts to retain the paper of cardboard material in position during treatment thereof. The metal foil comprises openings inside the cutting edge, which openings communicate with other bores in the cylindrical surface whereby the punched-out portion of the window is initially also retained by a vacuum and blown away by an air blast on completion of the punch operation. The prior art panel cutting apparatuses suffer from numerous drawbacks, the most acute being the lack of adjustability of the apparatus to cut out panels of different sizes as well as at different locations on the blank. In most cases, from one production run to another, it is necessary to use different cutting dies and, consequently, different die holders. The cutting dies and the die holders are expensive parts since they require an extensive machining work to be fabricated. Also, the installation of the cutting die and the die holder on the panel cutting apparatus requires long and fastidious adjustments resulting in a loss of production time. An object of the invention is an improved cutting tool for cutting serially panels from blanks of sheet-like material. Another object of the invention is an improved holder for a panel cutting tool used for serially cutting panels from blanks of sheet-like material. The objects of this invention are achieved in that the seat is devided into a plurality of portions, each portion being disposed between two of said clamping means (30), and in that said holder further comprises a plurality of vacuum chambers each being adapted to communicate with a source of vaccum via an orifice included in said driving shaft, each vacuum chamber being associated with a respective portion of the seat and communicating therewith through a plurality of passageways for creating a zone of vacuum in the vicinity of said opening means to retain a panel cut from said sheetlike material to the cutting plate. The subclaims directed to a holder or a rotary cutter show further details. The cutting plate, according to the present invention is manufactured by a method similar to the photoengraving process, known in the art of printing. Basically, a metallic plate having a thickness of approximately 0,159 cm (one sixteenth of an inch) is coated with a chemical sensitive to light. The plate is then covered with a mask leaving exposed only the area on which the cutting edge is to be formed. After subjecting the plate to light rendering the chemical acid-resistant, the plate is dipped into an acid bath for a certain period of time. The acid dissolves the plate at the non-exposed areas to form the cutting edge. For carrying out the panel cutting operation, the cutting plate is mounted on a cylindrical plate holder which, in a preferred embodiment of the invention, is of such design to accept cutting plates of different sizes. With this arrangement, in most cases, to set the panel cutting apparatus for a new production run, only the cutting plate needs to be changed. The plate holder is provided with a seat for receiving the cutting plate which is retained therein by means of keys clamping opposite edges of the cutting plate. In a specific embodiment, the seat extends about half the circumference of the cylindrical holder and is provided with four keys dividing the seat in three portions, each portion being bound by two adjacent keys. With such an arrangement, the seat may receive plates of three different lengths. However, it is plain that more or less than four keys may be used on the holder. The cutting plate and the holder define a rotary cutter which is adapted to be mounted on a conventional panel cutting apparatus. At this end, the holder is provided with a central cavity for receiving the drive shaft of the panel cutting apparatus. In the walls defining the central cavity are formed individual vacuum chambers in the form of depressions or recesses, each vacuum chamber being associated with a portion of the seat. Each vacuum chamber communicates with a respective portion of the seat by small air passages and also communicates with a vacuum supply orifice on the drive shaft. The operator of the panel cutting apparatus may select the portion of the seat at which vacuum will be applied by controlling the vacuum supply at the orifices of the drive shaft and supplying vacuum only in the desired vacuum chamber. Therefore, the present invention includes in a general aspect a rotary cutter for serially cutting panels from blanks of sheet-like material, the rotary cutter comprising: a thin metallic cutting plate on which is formed integrally a cutting edge having a contour corresponding to the outline of a panel to be cut, the cutting plate further comprising opening means formed on an area on the cutting plate which is edged by the cutting edge; and a holder for the cutting plate, the holder being adapted to be mounted on a driving shaft for rotation about an axis in order to bring successively in engagement the cutting plate with the blanks to cut serially panels therefrom, the driving shaft including an orifice communicating through a conduit means with a source of vacuum, the holder including: a) a seat for receiving the cutting plate; b) clamping means for retaining the cutting plate in the seat; and c) passageway means extending between the seat and the orifice when the holder is mounted on the shaft for creating a zone of vacuum in the vicinity of the cutting edge, wherein when the cutting edge engages a blank and cuts a panel therein, the vacuum zone retains the panel to the cutting plate. The present invention further comprises a holder for a thin metallic cutting plate adapted to cut serially panels of sheet-like material, on the cutting plate being formed integrally a cutting edge having a contour corresponding to the outline of a panel to be cut, the cutting plate further comprising opening means formed on an area on the cutting plate which is edged by the cutting edge, the holder being adapted to be mounted on a driving shaft for rotation about an axis in order to bring the cutting plate successively in engagement with the blanks to serially cut panels therefrom, the driving shaft including an orifice communicating with a source of vacuum through a conduit means, the holder being generally elongated and comprising a cavity which is adapted to receive the shaft, the holder including: a) a seat adapted to receive the cutting plate; b) clamping means for retaining the cutting plate in the seat; and c) passageway means extending between the seat and the orifice when the holder is mounted on the driving shaft in order to create a zone of vacuum in the vicinity of the opening means, wherein when the cutting plate engages a blank to cut a panel therefrom, the zone of vacuum retains the blank to the cutting plate which carries the panel away from the blank. The invention also comprehends a thin metallic cutting plate for serially cutting panels from blanks of sheet-like material, the cutting plate comprising a cutting edge integrally formed on the cutting plate, the cutting edge having a contour corresponding to the outline of a panel to be cut, the cutting plate further comprising opening means formed on an area on the cutting plate, the area being edged by the cutting edge, the opening means being adapted to be connected to a source of vacuum to create a zone of vacuum in the vicinity of the opening, the cutting plate being adapted to move successively in engagement with the blanks to serially cut panels therefrom, wherein when the cutting plate cuts a panel from a blank the vacuum zone retains the panel to the cutting plate. A preferred embodiment of the present invention will now be described with reference to the annexed drawings in which: Figure 1 is an elevational view on an enlarged scale of a panel cutting tool in the form of cutting plate; Figure 2 is a holder for a cutting plate according to the invention, the cutting plate being mounted on the holder and defining therewith a rotary cutter; Figure 3 is an elevational view of a holder for the cutting plate shown in Figure 2, the cutting plate being omitted; Figure 4 is a side view of the holder shown in Figure 2; and Figure 5 is a sectional view taken on lines 5-5 of Figure 3. Referring now to the drawings, more particularly to Figure 1 in which is illustrated a cutting tool, designated generally by the reference numeral 10, for serially cutting panels from envelope blanks of paper. The cutting tool comprises a metallic cutting plate 12 having approximately a thickness of 0,159 cm (one sixteenth of an inch). On cutting plate 12 is formed integrally a continuous cutting edge 14 having a contour corresponding to the outline of a panel to be cut, which in this particular case has a rectangular configuration with rounded corners. It should be understood, however, that cutting edges with different shapes may be formed on cutting plate 12. The cutting plate 12 also comprises a plurality of openings 16 which are surrounded by the cutting edge 14. The purpose of the openings 16, as it will be explained in details hereinafter is to allow a zone of vacuum to be formed in the vicinity of the cutting edge 14 to retain the panel which is cut from each blank, to the cutting plate and carry away the panel from the blank. For carrying out the cutting operation, the cutting plate 12 is mounted on a rotary cutting plate holder 17, shown in Figure 2, the cutting plate 12 and the plate holder 17 defining a rotary cutter 18. The rotary holder 17 extending along an axis 19 has a cylindrical shape and is formed by two halves 20 and 21 attached to each other by bolts 22. Halves 20 and 21 define a central cavity 23. More specifically, referring to Figures 2 to 5, the outer surface of half 21 defines a semi-cylindrical seat 26 for receiving the cutting plate 12. On the seat 26 are formed four grooves 28 extending along the axis 19, each groove receiving a key 30 which is retained therein by means of screws 32. Each key 30 is biased by two coil springs (not shown) compressed between the key 30 and its respective groove 28 to eject the key 30 from the groove 28 when the screws 32 are released. The seat 26 is divided in three portions 34, 36 and 38, respectively, each portion being bound between two adjacent keys. Portions 34, 36 and 38 of seat 26 communicate with respective vacuum chambers 40 42 and 44 by means of small air passages 46 uniformly distributed on the surface of seat 26. On the surface of seat 26, the ends of passages 46 are interconnected by shallow circumferentially extending grooves 47. Each vacuum chamber is constituted by a depression or a recess formed on the inner walls of half 21 and is separated from an adjacent vacuum chamber by a partition 49. The vacuum chambers 40, 42 and 44 are closed at each end of the plate holder 17 by end walls 50. To mount the cutting plate 12 on the holder 17, two opposite edges 48 of the cutting plate 12 are clamped by two keys 30 on the seat 26, as shown in Figure 2. The specific structure of the holder shown in Figures 2 to 4 is such as to accept plates of three different lengths. More specifically, for applications where the panel to be cut is small, a short cutting plate 12 will be used. In such case, the cutting plate will extend only over the portion 34 of the seat 26. When the panel to be cut has a surface exceeding the surface of portion 34, a cutting plate 12 of intermediate length may be used. In such case, the cutting plate will overlie portions 34 and 36. At last, where extremely large panels are to be cut out a long cutting plate is mounted on holder 17, extending over the entire surface of seat 26. It should be understood that more or less than four keys may be provided on the seat 26 without departing from the spirit of the invention. For example, for applications where panels of one size are cut most of the time, only a pair of keys may be provided on the holder 17 to retain only single sized cutting plates. On the contrary, in situations when during each production run only small quantity of envelopes are produced and the size as well as the location of the window on the envelope varies from one production run to another, it is preferable to employ a cutting plate holder of more universal design, which can accept plates of different sizes. The rotary cutter 18 is adapted to be installed on a conventional panel cutting apparatus. An example of such apparatus is given in the United States Patents 3 106 121 granted to A. Novick on October 8, 1963. Basically, the panel cutting apparatus comprises a conveyor to move in serial order to the envelope blanks to a cutting station where the rotary cutter cuts out the panels. The rotary cutter is mounted on a drive shaft, which is schematically illustrated in Figures 2, 4 and 5 and is designated by the reference numeral 53. The drive shaft 53 is provided with three orifices 54, 56 and 58 communicating with vacuum chambers 40, 42 and 46, respectively. The orifices 54, 56 and 58 also communicate with an internal conduit (not shown) in the drive shaft connected to a source of vacuum. The vacuum supply to each orifice may be controlled by means of valves by the operator of the apparatus. Thus, according to the length of the cutting plate 12 to be used, the operator may apply vacuum only to the desired orifice and the associated vacuum chamber to create a vacuum zone in the desired portion of the seat 26. For example, when a short cutting plate 12 is used, which occupies only the portion 34 of seat 26, vacuum will be applied only to orifice 54 to create a suction on the surface in the portion 34 only. Similarly, when a cutting plate 12 of intermediate length is used vacuum is applied to orifices 54 and 56 and when a long cutting plate 12 is mounted in seat 26, vacuum is supplied in all the orifices. When the cutting plate 12 is mounted on the cutting plate holder 17, the suction created on the back of the cutting plate 12 allows, through the openings 16 to form a localized vacuum zone in the vicinity of the cutting edge 14. During the panel cutting operation, when the cutting edge 14 engages and cuts out a panel, the local vacuum zone retains the panel to the cutting plate 12 and the panel is carried away from the blank. When the cutting edge has travelled to a position away from the blank, the vacuum is shut-off and the panel is blown into a waste basket. The vacuum control system of the panel cutting apparatus which enables to control the vacuum supply to the orifices 54, 56 and 58 and which also shuts-off the vacuum to release the cutted panel in the waste basket, will not be described in details here since it is well known in the art. The rotary cutter 18, according to this invention, apart its ease of adjustability to cut out different panels has some other advantages over the prior art rotary cutters. A first advantage resides in the elimination of the rubber rollers used to engage the envelope blanks to ensure registration accuracy during the cutting of the panels. The cutting plate 12 being relatively thin, the rotary cutter 18 has a smooth overall shape and thus, it may be used as a roller to advance and maintain the blanks in the proper position during the cutting operation. A second advantage resides in the possibility of improving the productivity of the panel cutting apparatus by increasing the speed of rotation of the rotary cutter, which is possible because the cutting plate 12 is light and the rotary cutter 28 is generally well balanced. Thus, it may be rotated at higher speeds without overstressing the bearings of the drive shaft on which it is mounted. The panel cutting plate 12 is manufactured by a method similar to the photoengraving process used to produce intaglios. The first step for manufacturing the cutting plate 12 consists of making a mask or screen constituted by a film which is opaque over the major portion of its surface except at locations where the cutting edge is to be formed. The position and the size of the transparant zone on the mask is determined according to the size and the location of the window on the envelope. Subsequently, the mask is applied to a metallic plate which is coated with a substance sensitive to light. After an exposure to a light source, which renders the light sensitive substance at the transparant zone of the mask corrosive-resistant, the plate is dipped into a corrosive bath, such as acid for a period of time sufficient to etch away the non-exposed areas of the plate and form a suitable projecting cutting edge.

Claims: A holder (17) for & thin metallic cutting plate (12) capable to cut panels from sheet-like material such as paper or the like, the metallic plate (12) comprising a cutting edge (14) integrally formed on the said plate (12) and having a contour corresponding to the outline of a panel to be cut in said material, the metallic plate (12) further comprising opening means (16) formed on an area thereof emcompassed by the cutting edge (14), said holder (17) being mounted on a shaft (53) rotating said holder (17) about a rotation axis (19) in order to bring the cutting plate (12) into engagement with the sheet-like material, and said bolder including a seat (26) for receiving the cutting plate (12) and clamping means (30) for retaining said cutting plate (12) in the seat (26); characterized in that the seat (26), is divided into a plurality of portions (34, 36, 38), each portion being disposed between two of said clamping means (30), and in that said holder (17) further comprises a plurality of vacuum chambers (40, 42, 44) each being adapted to communicate with a source of vacuum via an orifice included in said driving shaft, each vacuum chamber (40, 42, or 44) being associated with a respective portion (34, 36, or 38) of the seat (26) and communicating therewith through a plurality of passageways (46) for creating a zone of vacuum in the vicinity of said opening means (16) to retain a panel cut from said sheet-like material to the cutting plate (12). A holder as recited in claim 1, characterized in that said clamping means comprises a plurality of spaced apart keys (30) to retain the cutting plate (12) in the seat (26), the cutting plate (12) comprising two opposite edges clamped by two of said keys (30) and each portion (34, 36, or 38) of the said seat (26) being bound by two adjacent keys (30). A holder as recited in claim 1, wherein said holder (17) is generally cylindrical and comprises a central cavity (23) for receiving the shaft (53), characterized in that the cavity (23) defines a wall in which are formed a plurality of depressions defining said vacuum chambers (40, 42, 44) and in that said shaft (53) includes a plurality of orifices (54, 56, 58) each communicating with one of the vacuum chambers (40, 42, 44). A holder as recited in claim 2, characterized in that it comprises a set of four keys (30). A holder as recited in claim 2, characterized in that the keys (30) extend along said rotation axis (19). A holder as recited in claim 1, characterized in that each portion (34, 36, or 38) of the seat (26) comprises a plurality of orifices distributed over substantial!y the entire surface of the said portion (34, 36, or 38), said plurality of orifices communicating with the vacuum chamber (40, 42, or 44) associated with the seat portion through the passageways (46). A rotary cutter (18) for cutting panels from sheet-like material such as paper or the like, comprising: a thin metallic cutting plate (12) on which is formed integrally a cutting edge (14) having & contour corresponding to the outline of a panel to be cut in said material, the metallic plate (12) further comprising opening means (16) formed on an area thereof emcompassed by the cutting edge (14); and a holder (17) for the metallic cutting plate, said holder (17) being mounted on a shaft (53) rotating said holder (17) about a rotation axis (19) in order to bring the cutting plate (12) into engagement with the sheet-like material, and said holder including a seat (26) for receiving the cutting plate (12) and clamping means (30) for retaining said cutting plate (12) in the seat (26), characterized in that the seat (26) is divided into a plurality of portions (34, 36, 38) each portion being disposed between two of said clamping means (30), and in that said holder (17) further comprises a plurality of vacuum chambers (40, 42, 44) each being adapted to communicate with a source of vacuum via an orifice included in said driving shaft, each vacuum chamber (40, 42, or 44) being associated with a respective portion (34, 36, or 38) of the seat (26) and communicating therewith through a plurality of passageways (46) for creating a zone of vacuum in the vicinity of said opening means (16) to retain a panel cut from said sheet-like material to the cutting plate (12). A rotary cutter as recited in claim 7, characterized in that said clamping means comprises a plurality of spaced apart keys (30) to retain the cutting plate (12) in the seat (26), the cutting plate (12) comprising two opposite edges clamped by two of said keys (30) and each portion (34, 36, or 38) of the said seat (26) being bound by two adjacent keys (30). A rotary cutter as recited in claim 7, wherein said holder (17) is generally cylindrical and comprises a central cavity (23) for receiving the shaft (53), characterized in that the cavity (23) defines a wall in which are formed a plurality of depressions defining said vacuum chambers (40, 42, 44) and in that said shaft (53) includes a plurality of orifices (54, 56, 58) each communicating with one of the vacuum chambers (40, 42, or 44). A rotary cutter as recited in claim 8, characterized in that it comprises a set of four keys (30). A rotary cutter as recited in claim 8, characterized in that the keys (30) extend along said rotation axis (19). A rotary cutter as recited in claim 7, characterized in that each portion (34, 36, or 38) of the seat (26) comprises a plurality of orifices distributed over substantially,the entire surface of the said portion (34, 36, or 38), said plurality of orifices communicating with the vacuum chamber (40, 42, or 44) associated with the seat portion through the passageways (46).

Inventors: FALASCONI, ROLAND
Applicants: ROFALEX INTERNATIONAL INC.
Application year: 1987
Main classification: B31B1
IPC codes: B26D7, B31B19, B31B1, B26F1