Knife bending apparatus

Abstract: Apparatus for bending a sheet die cutting knife (A) to a specified shape. The knife (A) is supported by a supporting mechanism (8) and an energy-charging mechanism (9) in connection with the upper face of a surface plate (7). The edge portion of a bending die (24, 24') which constitues a bending mechanism (10) is brought into contact, through vibrations and drive, with the knife side opposite to the direction along which the knife is about to be bent, by alternatively repeating a specified staying time and knife send-out time. The knife (A) is sent out from the supporting mechanism (8) by a send-out mechanism every time such a bending process is carried out, thereby causing the same to be bent to a specified curvature radius. It is possible to bend the knife to various shapes by properly changing the operating time of the bending mechanism and the send-out mechanism with a control device (39).

Description: BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a knife bending apparatus according to the preamble of claim 1, which is used for die cutting and creasing such sheet-like materials as paper, plastic sheets, corrugated paper, etc to a specified shape by die cut pressing etc. Description of the Prior Art For example, as shown in FIG. 12, this kind of knife "A" is like a thin band (for example, the thickness is 0.4mm to 1.0mm), has a blade edge 1 and is formed so that the section thereof is roughly rectangular. And, during use, the knife "A" is fitted and fixed in a knife insertion groove 3 which has been pierced and consecutively formed on a wooden knife retainer block 2. The knife insertion groove 3 has been formed in advance to a required shape (shape corresponding to a die cut shape) by, for example, laser beam machining. On the other hand, for the knife "A", the back 6 side thereof is placed along a surface plate, not shown, and at the same time is put and pressed with a set of bending die from both the sides of the knife "A", thereby causing a specified bending portion 5 to be formed. Hence, in a conventional apparatus used for bending a knife "A" as described above, because the knife "A" springs up or is inclined on the surface plate due to such actions that the knife "A" is put and pressed from both the sides of the knife "A" by a set of die, such a problem as being impossible to obtain an accurate bending angle for the back 6 of the knife "A" occurs. Furthermore, in the conventional bending apparatus, such a problem as the knife "A" having to be repeatedly put and pressed with the bending die continuously a considerable number of times to conquer a springback phenomenon (resilient rebound) of the knife "A" occurs, thereby preventing any efficient bending process from being carried out. A knife bending apparatus according to the preamble of claim 1 is known from EP-A-0 317 637. SUMMARY OF THE INVENTION The present invention has been developed in view of the above situations, and it is an object of the invention to provide a bending apparatus which can very efficiently bend the knife so that an accurate bending angle for the back thereof can be obtained by making the back of the knife run along on a surface plate. The above object is accomplished by a knife bending apparatus as defined in claim 1. With the knife bending apparatus according to the invention, elongation of a knife material in line with the elastic deformation in the bending process can be preferably absorbed at the bending portion, and the knife is bent to an accurate bending angle without shearing, with reference to the upper face of the surface plate. Furthermore, in the bending apparatus according to the abovementioned composition, since it is possible to properly change the bending action amount of the bending mechanism for the knife and the feed amount of the knife by the feed mechanism, the springback phenomenon for the knife can be preferably suppressed, and it is possible to remarkably efficiently carry out bending processes to a specified shape. Namely, in the apparatus, the knife back is made to run along on the surface plate, the springback phenomenon is preferably suppressed so that an accurate bending angle for the back can be obtained, and it is possible to very efficiently work or bend the knife. Still furthermore, it is possible to form the knife in various kinds of shapes by properly changing the action amounts of the bending mechanism and feed mechanism by means of a control device. Still additionally, as the bending mechanism can stay at the position, where the bending mechanism operates on the knife, for a specified period of time, the springback phenomenon for the knife can be preferably suppressed, and the bending process is remarkably efficient. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a bending apparatus according to a preferred embodiment of the present invention, FIG. 2 is a plan view of the bending apparatus, FIG. 3 is a front view of the bending apparatus, FIG. 4 is an enlarged view of the portion shown with the arrow B of FIG. 2, FIG. 5A is a perspective view showing a knife bending die, which forms part of the bending apparatus, FIG. 5B is a front view thereof, FIG. 5C is a plan view thereof, FIG. 5D is a side view thereof, and FIG. 5E is an enlarged cross sectional view of essential parts of FIG. 5C, FIG. 6A is a front view showing a base to retain the bending die, FIG. 6B is a plan view thereof, and FIG. 6C is a side view thereof, FIG. 7A is a front view showing the knife bending die according to another preferred embodiment, FIG. 7B is a cross sectional view taken at the line marked with the arrows C-C' in FIG. 7A, and FIG. 7C is a side view thereof, FIG. 8 is a perspective view of a press roller device which forms part of the bending apparatus, FIG. 9A is a side view showing the detailed structure of the press roller device, and FIG. 9B is a front view thereof, FIG. 10 is a graph showing the actions of the bending die to be used when bending a knife by the bending apparatus, Figures 11a, b and c are plan views of the knife which has been bent by the bending apparatus, and FIG. 12 is a perspective view of the knife retainer block before a knife is installed on the knife retainer block, for the purpose of explaining the background art of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS With reference to the drawings attached herewith, a preferred embodiment in which the present invention is embodied will be described for a better understanding of the invention. The following preferred embodiment is only one of the examples in which the present invention is embodied and is not of such a nature that it limits the technical scope of the invention. As shown in FIGS. 1 to 4, a bending apparatus in accordance with the preferred embodiment comprises a supporting mechanism 8 to slidably support a knife "A" from both its sides in such a state that the back 6 (one end side in its lengthwise direction) of the knife "A" is made to run along the upper face of a surface plate 7, a biasing mechanism 9 to bias the knife "A" toward the upper face of the surface plate 7, a bending mechanism 10 to be placed adjacent to the supporting mechanism 8 with a specified clearance "t" (See FIG.4) and to repeatedly give a bending force to the knife "A" which is supported by the supporting mechanism 8, a feed mechanism 11 to feed the knife "A" from the supporting mechanism 8 every time when bending process is carried out by the bending mechanism 10, and a control device 39 to change the bending action amount of a bending die 24 of the bending mechanism 10 for the knife "A" and/or the feed amount of the knife "A" by the feed mechanism 11. The supporting mechanism 8 is provided with a block 12 having a groove to receive the knife "A" and the clearance "t" between a spacer 13 attached to the front face of the block 12 and the bending mechanism 10 can be adjusted by properly changing the spacer 13. As shown in FIGS. 8 and 9, the biasing mechanism 9 is arrayed opposite to the upper face of the surface plate 7 and consists of a press roller device which presses the knife "A" onto the upper face of the surface plate 7. The press roller device defines a supporting groove 15a to fit and insert the blade edge 1 of the knife "A" to the circumferential face of a roller 15 which is rotatably supported by a shaft 14 and to support the tapered face thereof. The shaft 14 is rockably supported by a supporting shaft 16 against the upper face of the surface plate 7, and at the same time is elastically biased toward the upper face by a spring 17 which is an example of an energy-charging means. Namely, a long slit 18a is pierced and formed in the lengthwise direction of a bracket 18 which supports the roller 15, and the support shaft 16 attached to a bracket 19 is slidably inserted into the long slit 18a. The bracket 19 is provided with an operating lever 20, and the bracket 19 is slidably supported by a bracket 21 attached to the bending apparatus body in the same direction as the lengthwise direction of the long slit 18a of the bracket 18. The spring 17 intervenes between the position corresponding to the intermediate portion pertaining to the lengthwise direction of the long slit 18a on the bracket 18 and the bracket 21. Therefore, in the case that an operator grasps the operating lever 20 and operates it, for example, in the direction of the arrow 22a in the press roller device according to the above construction, the supporting shaft 16 moves to the position shown with a broken line in FIG. 9A, and the roller 15 is biased toward the upper face of the surface plate 7 with an elastic energy charged in the spring 17. On the other hand, in the case that the bracket 19 is made to move in the direction of the arrow 22b by operating the lever 20, the supporting shaft 16 will move to the position shown with a solid line in FIG. 9A, and the roller 15 will be rockably biased upwards by the action of the spring 17. Also, in this case, the rocking position is regulated by a stopper 23. That is, the press roller device relatively varies the position of the supporting shaft 16 relative to the position determined by the biasing force of the spring 17, thereby causing the direction in which the roller 15 is biased relative to the upper face of the surface plate 7 to be properly selectively changed. Therefore, in the press roller device, it is possible to press the knife "A" onto the surface plate 7 without damaging the blade edge 1 of the knife "A" and to retain it without fail, and at the same time the press roller device can properly correspond to changes in the height of the knife "A". Furthermore, it is very easy to change the retaining state and the releasing state relative to the knife "A" only by simply operating the lever 20 in the forward and backward direction. The bending apparatus 10 is composed of the bending die 24 (See FIG. 5) for bending the knife "A" through operating on the side of the knife "A". The bending die 24 is composed of a thin plate-like member, and roughly at the middle portion thereof, a groove 24b provided with an edge portion 24a, which will become parallel to both the sides of the knife "A" when the knife "A" passes therethrough with a proper clearance, is formed by, for example, a wire cutting process. The edge portions 24a are hardened. The abovementioned proper clearance is of such a dimension that one edge portion 24a can be brought into contact with either side (the side opposite to the direction along which the knife "A" is about to be bent) of the knife "A" when the bending die 24 is vibrated as described later. Namely, it is of such a dimension that both the edge portions 24a are not brought into contact with both the side portions of the knife "A" in line with the vibrations of the bending die 24. An arcuate circumferential face 24c defined by a curvature radius R is inscribed at the front side of the bending die 24 for the purpose of easy transit of the knife "A" after it has been bent. The bending die 24 composed as stated above is removably fitted in a base 25 (See FIG. 6) equivalent to a holder and is retained with screws at its upper and lower parts. At the base 25, the lower end portion thereof is slidably supported by a slide bearing 26, linearly as illustrated, in the right angle direction (the direction of the arrows 28a and 28b) relative to the feed direction (the direction of the arrow 27) of the knife "A". The base 25 is vibrated and driven, along with the bending die 24, in the bending direction of the knife "A" by a motor 30 which is controlled through a crank 29 by the control device 39. In order to obtain the rectangularity by preventing the inclination (the inclination in the direction of the arrow 27 of the upper part of the bending die 24) of the bending die 24 in connection with the upper face of the surface plate 7, the upper part of the base 25 is supported at the L-shaped end of a supporting member 31 which is formed to be roughly L-shaped. The base 25 is slidable in the right and the left directions (the directions of the arrows 28a and 28b) relative to the supporting member 31. With the bending die 24 being composed as stated above, as the groove 24b is formed as described above, the parallelism of the edge portions 24a relative to the side of the knife "A" can be secured, and a bending process can be carried out, with accurate rectangularity obtained, without such an inconvenience as a warping caused to be present in the knife "A". Besides, because the bending die 24 is formed to be thin, it is possible to carry out bending processes of comparatively small curvature radius for the knife "A". Figure 10 is a graph showing the action of the bending die versus the time T. Position A represents the position in which the die starts contacting a knife. Position B represents the position in which the die starts parting from the knife. Position C represents the position in which the die starts parting from the knife in a conventional apparatus. The distances d1 and d2 represent springback amounts. As shown in FIG. 10, as the bending die 24 is controlled by a control device 39 so that it can stay, for a specified pressing time (the period of staying time: the period of stopping time in such a state that the bending die 24 is in contact with the side of the knife "A") T 1 , at the position operating on the knife "A", the springback amount on the knife "A" will be substantially decreased more than in any conventional apparatus, thereby causing a remarkably efficient bending process to be carried out. That is, the number of times of bringing the bending die 24 into contact with the side of the knife "A" can be much decreased. When it is assumed that, for example, the material of the knife "A is a general blade material and its thickness is 0.7mm to 1.0mm, it is preferable that the staying time T 1 is about 0.3 to 0.4 seconds. Besides, in the bending apparatus, the control device 39 is concurrently provided with a function to change the bending action amount relative to the knife "A" in the vibration actions of the bending die 24 and the feed amount of the knife "A" by the feed mechanism 11, for example, whenever carrying out bending processes. Therefore, in the apparatus, it is possible to work the knife "A" to various shapes, for example, bellows, arcuate or spiral shape, etc. (See Figures 11a, b and c). In Figure 11c segment A is a circular arc, the bending of which is achieved by repeatedly feeding the knife over a constant distance. Segment B is obtained by feeding the knife over variable distances. Below will be described one of the examples of the control thereof. For example, in the case that a bending process is performed on the knife "A" so that the curvature radius becomes, for example, 5mm, while it is assumed that the feed amount of the knife "A" by the feed mechanism 11 is variable in the range from 0.3 to 2mm, the bending die 24 is actuated at a constant bending action amount as the knife "A" is sent out repeatedly three to five times by a pitch of 0.5mm at every bending process. It is thereby possible to simply bend the knife "A" to a circular arc shape of small radius with high accuracy. Furthermore, the knife "A" can be formed to be like a vortex in its plan view by gradually increasing the feed amount by the feed mechanism 11. Simultaneously, the bending amount of the bending die 24 may be gradually changed. In the case that the knife "A" is bent by 90° in its plan view, the knife "A" is bent by 45° by the bending die 24 in the first bending process. Thereafter, the knife "A" is fed by 0.5mm by the feed mechanism 11, and it is further bent by 45° by the bending die 24. Then, the knife "A" is thereby bent by almost 90° visually. As shown in FIG. 6, the base 25 according to the preferred embodiment is provided at the upper part of the retaining position of the bending die 24, with screws 37 and 38 for micro adjustment of the inclination degree (the inclination angle in the directions of the arrows 28a, 28b in connection with the upper face of the surface plate 7) of the bending die 24 in its right and left directions. The screws 37, 38 are properly adjusted to incline the bending die 24 relative to the surface plate 7. In the case that the knife "A" is bent under this condition, the knife "A" is given a distributary force in the direction along which it is pressed down toward the upper face of the surface plate 7. As a result, it is possible to carry out bending in such a state that the knife "A" back 6 is always applied to the upper face of the surface plate 7. FIG. 7 shows a bending die 24' according to another preferred embodiment. In the bending die 24', notches 24d, 24d are formed at both sides of the edge part 24a, putting it therebetween. Thus, by providing a notch 24d like this, it is possible to insert and pass the edge part of the knife "A" which has been bent, into the notch 24d, thereby causing the knife "A" to be repeatedly bent. The feed mechanism 11 is provided with a plurality of rollers 32a, 32b, 33a, 33b, 34a, 34b so that the knife "A" is held from both its sides and is fed in the direction of the arrow 27. Each of these rollers is driven synchronously by a motor 36 through an interlocking mechanism 35 consisting of a plurality of belts, pulleys, etc. The rollers 32b, 33b properly correspond to the thickness of the knife "A" and are supported so that their position relative to the knife "A" can be changed, thereby causing the rollers 32b, 33b to be elastically biased in the direction of the arrow 28b at all times. The motor 36 is controlled synchronously with the motor 30. In the bending apparatus composed as described above, a knife "A" is retained by the supporting mechanism 8 and the biasing mechanism 9, relative to the upper face of the surface plate 7. The knife "A" which is retained as shown above will be bent by the bending mechanism 10. Namely, the base 25 is vibrated and driven by the motor 30 so that one edge portion 24a of the groove 24b of a bending die 24 comes in contact with the knife side opposite to the direction along which the knife "A" is about to be bent. As the edge part 24a whose parallelism is secured relative to the knife "A" side is vibrated and driven linearly, repeating a specified staying time T 1 and knife "A" sending time T 2 by turns, with the edge part 24a vertically standing in connection with the surface plate 7, the knife "A" will be bent with an accurate rectangularity obtained. Thus, every time when the bending process is carried out, the knife "A" is fed from the supporting mechanism 8 by the feed mechanism 11 and is bent to a specified curvature radius. With these procedures, elongation of the knife material in line with the elastic deformation in bending can be preferably absorbed at the bending portion thereof, and at the same time its springback can be suppressed. More over, the knife "A" is very efficiently bent to an accurate angle, with reference to the upper face of the surface plate 7, without any shearing. Furthermore, in this case, it is possible to bend and form the knife "A" in various shapes in its plan view by properly controlling the bending action amount of the bending die 24 and the feed amount of the knife "A" by the feed mechanism 11 by the control device 39. In the bending apparatus according to the above construction, in the case that the clearance "t" formed between the block 12 which constitutes the supporting mechanism 8 and the bending die 24 which constitutes the bending mechanism 10 is made zero, the knife "A" can be sheared with an accurate rectangularity at a specified dimension.

Claims: A knife bending apparatus for bending a long and thin plate-like knife blank into a band knife, comprising: a supporting mechanism (8) to slidably support a knife blank (A) from both its flat sides by means of a receiving groove, with one of the longitudinal edges of the knife blank being supported by the upper face of a support plate (7) and said receiving groove being defined by the supporting mechanism in a plane perpendicular to the longitudinal direction of the blank, a bending mechanism (10) placed adjacent to the supporting mechanism (8) in downstream direction with a specified clearance (t), and a feed mechanism (11) to feed the knife blank (A) relative to the supporting mechanism (8); said feed mechanism (11) being arranged to intermittently feed the knife blank (A) over predetermined distances, said bending mechanism being actuated for applying a bending force to the knife blank (A) after each feed cycle in a direction perpendicular to the feed plane of the knife blank (A), and said bending mechanism comprising a bending member oriented perpendicular to the feed direction of the knife blank (A), with said bending member being provided with at least one edge portion parallel to the feed plane of the knife blank and being movable in a direction perpendicular to the feed plane of the knife blank (A); characterized by a biasing mechanism (9) to elastically press the knife blank (A) onto the upper face of the support plate (7) with a press roller (15) having a circumferential groove (15a) to fit and insert one of the knife blank edges (1) for clamping the knife blank (A) between said press roller (15) and the upper surface of the support plate (7). A knife bending apparatus as claimed in claim 1 comprising a control device (39) to change the amount of bending action applied by the bending mechanism (10) to the knife blank (A). A knife bending apparatus as claimed in claim 1 or 2 comprising a control device (39) to change the amount of feeding action applied to the knife blank (A) by the feed mechanism (11). A knife bending apparatus as claimed in claim 1 comprising a control device (39) to set, to a specified value, the staying time of the bending mechanism (10) at its operating position for the knife blank (A) during the time from the start of the bending action of the knife to the end thereof by the bending mechanism and to repeatedly make the bending mechanism operate for bending at an adequate interval of time. A knife bending apparatus as claimed in any one of the preceding claims, wherein said groove (15a) is provided in the circumferential surface of the roller (15), with the knife back (6) running along on the upper face of the support plate (7), said groove (15a) supporting the tapered face of the blade edge, and said roller (15) being rockably supported by a supporting shaft (16), with energy being applied to said roller (15) by an energy-storage means (17) in a direction toward the upper face of said support plate (7). A knife bending apparatus as claimed in claim 5, wherein the supporting position of the roller (15) by the supporting shalt (16) is relatively variable with respect to the position of application of energy by the energy-storage means (17), to thereby selectively change the direction in which the roller (15) is biased with respect to the upper face of the support plate (7). A knife bending apparatus as claimed in any one of the preceding claims, wherein the bending member is a bending die (24, 24') which is composed of a plate-like member provided, roughly at the middle portion thereof with a slot (24b) having an edge portion (24a) which becomes parallel to both flat sides of the knife blank (A) when the knife blank passes therethrough with a proper clearance. A knife bending apparatus as claimed in claim 7, wherein the bending die (24, 24') has one end thereof linked with a drive mechanism (29, 30) which reciprocates the bending die in a direction normal to the feed plane of the knife blank (A), the other end of the bending die being supported by a supporting member (31) which prevents an inclination of the bending die normal to the direction in which the bending die is moved by the drive mechanism.

Inventors: CHUJI YANAGIMOTO, CHUJI, YANAGIMOTO, Chuji, Yanagimoto, c/o Itami Industrial Co.,Ltd.
Applicants: ITAMI IND CO LTD, ITAMI INDUSTRIAL CO., LTD.
Application year: 1993
Main classification: B21D11
IPC codes: B21D11, B21D53