Abstract: The swivel knife holder assembly includes a shoulder screw defining an axis, and having a proximal threaded end and a distal head, and mounted on the shoulder screw is a bobbin assembly. The swivel knife holder assembly also includes a shell defining an interior, and having a distal opening and a proximal opening. A core is secured in the interior and is coupled to a knife for cutting fabric material. The proximal opening of the shell is defined by a flange and houses the shoulder screw therein. Threadably coupled to the proximal threaded end of the shoulder screw is a stem. The stem secures the bobbin assembly within the shell and also includes a mounting surface for engaging a reciprocating drive mechanism.

Abstract: A printer includes a first blade configured to be movable between a standby position and a cutting position, a second blade configured to contact the first blade located in the cutting position, a drive mechanism configured to drive the first blade, a first elastic member configured to pull the first blade located in the cutting position in a direction in which the first blade moves to the standby position, and a second elastic member configured to pull the first blade located in the standby position in a direction in which the first blade moves to the cutting position.

Abstract: A cutter can move a movable knife by two cutter drive gears without the movable knife becoming skewed. The cutter 10 of a mobile printer 1 has a fixed knife 11, and a cutter drive mechanism 32 that moves the movable knife 31 straight to and away from the fixed knife 11. The cutter drive mechanism 32 has two cutter drive gears 51 that are driven synchronously, and a cutter drive plate 54 disposed between the two cutter drive gears 51 and the movable knife 31. The two cutter drive gears 51 cause the cutter drive plate 54 to move to and away from the movable knife 31 on a longitudinal axis Y (direction of travel), thereby moving the movable knife 31 to and away from the cutter drive plate 54. If the cutter drive plate 54 becomes skewed when the two cutter drive gears 51 move the cutter drive plate 54, the guide mechanism 81 prevents skewing of the movable knife 31.

Abstract: A fixed blade support device includes a biasing member and a fixed blade support member (11). The fixed blade support member (11) includes a base surface portion (11a), an upright surface portion (11b), and a retainer portion (11c). The upright surface portion (11b) extends from the base surface portion (11a) in a biasing direction so as to close a rear side of a root portion of a fixed blade (12) on an opposite side to a blade edge portion thereof, and is configured to prevent the fixed blade (12) from being disengaged in a direction of engagement with a movable blade. The retainer portion (11c) extends from the upright surface portion (11b) so as to cover the root portion of the fixed blade (12), and is configured to prevent the fixed blade (12) from being disengaged in the biasing direction.

Abstract: A cutting assembly for a printer that includes a cutting frame that has opposing side walls is provided. The cutting assembly further includes a blade housing slidably mounted in the cutting frame for slidable movement along the side walls and a blade fixed in the blade housing that includes a cutting edge. The cutting assembly further includes a plurality of ejector posts that extends from the blade housing in a direction of blade housing slidable movement and past the cutting edge to engage media being cut by the cuffing edge.

Abstract: A punching device includes: a die seat; a punch seat; an interconnecting member interconnecting the die seat and the punch seat; a punch; first and second pivot parts; a first lever pivoted to the first pivot part and having two first side walls and two side flanges that extend respectively from lower ends of the first side walls; a second lever pivoted to the second pivot part and having two second side walls that abut against the side flanges for driving rotation of the first lever relative to the first pivot part; and an urging member for urging the punch.

Abstract: A tool support assembly for working on a surface is provided. The tool support assembly includes a track and a carriage movably mounted on the track. A connector link extends between and couples a tool to the carriage. The tool support assembly also includes a biasing mechanism for urging the tool towards the surface.

Abstract: Personal cutting devices in the form of hand held punches for producing jewelry display cards include two aligned templates having identical patterns of apertures and being securely mounted in a frame such that a space between the templates accommodates a piece of cardstock. There is a spring biased movable member having elongate cutting elements designed to pass through the apertures in both templates, and an activation lever on which indicia is printed to show the aperture patterns produced by the punches. A housing protects the mechanism. Each punch is specifically designed to produce a display card that can hold and display a single article of jewelry such as a pair of earrings, a necklace or a brooch. The punches vary in size according to the template patterns. The punches enable the jewelry designer to use any card stock, including a business card, to display an article of jewelry.

Abstract: A sheet cutter includes: a stationary knife including a straight blade part formed in a straight-line shape in a longitudinal direction; a movable knife including a cutting edge part formed in the shape of V-character, opposed to mesh with the straight blade part of the stationary knife, the movable knife being able to freely move toward or back from the stationary knife; a movable knife pressing member for pressing the movable knife against the stationary knife; and a movable knife driver driving the movable knife forward or backward. The movable knife pressing member pressure contacts the movable knife against the stationary knife by a compression coil spring contained inside the movable knife pressing member.

Abstract: A punching device includes: a die seat; a punch seat; an interconnecting member interconnecting a first end portion of the die seat and a first end portion of the punch seat; a punch supported movably on the punch seat; a first pivot part extending from at least one of the first end portion of the die seat and the first end portion of the punch seat; a second pivot part extending from a second end portion of one of the punch seat and the die seat; a lever mechanism including first and second levers, the first lever being pivoted to the first pivot part, the second lever being pivoted to the second pivot part for pressing one end of the first lever; and an urging member for urging the punch away from the die seat.

Abstract: A sheet feeding device includes a moving mechanism (20) configured to move a cutting edge (Ba) of a movable blade (B) away from a cutting edge (Aa) of a fixed blade A to move the cutting edge (Ba) of the movable blade (B) from an open position (X) where a fed sheet (S) is received and to place the cutting edge (Ba) of the movable blade (Ba) at an open position; a mechanism (35) biases the movable blade (B) toward the fixed blade (A) so that the cutting edge (Ba) of the movable blade (B) slides against the cutting edge (Aa) of the fixed blade (A) a blade spacing mechanism (40) moves the movable blade (B) away from the fixed blade (A) against a biasing force of the biasing mechanism (35) during a allowing the movable blade (B) to reach the open position (X) after cutting of the sheet S with the movable blade (B). The spacing mechanism (40) includes a cam (41) provided on the fixed blade (A) side and a cam follower (42) in contact with the cam (41) provided on the sides of the movable blade (B).

Abstract: A fixed blade support device includes biasing means and a fixed blade support member (11). The fixed blade support member (11) includes a base surface portion (11a), an upright surface portion (11b), and a retainer portion (11c). The upright surface portion (11b) extends from the base surface portion (11a) in a biasing direction so as to close a rear side of a root portion of a fixed blade (12) on an opposite side to a blade edge portion thereof, and is configured to prevent the fixed blade (12) from being disengaged in a direction of engagement with a movable blade. The retainer portion (11c) extends from the upright surface portion (11b) so as to cover the root portion of the fixed blade (12), and is configured to prevent the fixed blade (12) from being disengaged in the biasing direction.

Abstract: A cutter for a sheet-like member is provided with a moving base (36) on which an edge (30a) of a moving blade (30) is positioned facing an edge (32a) of a fixed blade (32) with a tilt. The moving blade (30) is fixed to the moving base (36), which moves the moving blade (30) relative to the fixed blade (32). The moving blade (30) is pressed against the fixed blade (32) by an elastic force along a short-side direction and is moved by the moving base (36) toward the fixed blade (32), to thereby shear a sheet-like member W placed between the moving blade (30) and the fixed blade (32).

Abstract: A cutter knife includes a cutter body 1 having a sliding contact portion 20 making sliding contact with a cutting object, a cutter member 2 having a cutting blade 22 for cutting the cutting object, a holder member 3 holding the cutter member 2 with the cutting blade 22 being protruded from the cutter body 1, and a biasing member 4 biasing the cutter member 2 to press the cutting blade 22 against the cutting object with a constant pressure when the sliding contact portion 20 of the cutter body 1 is in sliding contact with the cutting object.

Abstract: Methods and apparatus provide an input for a user located remote from a cutting machine to cut a part. The user can instruct the cutting machine to cut the part to the user's specification in many ways, for example such that the user can instruct the cutting machine without having knowledge of the machine's cutting processes or construction. The methods and apparatus of the embodiments described herein can convert a machine processes into an image of the part to be cut such that the user can easily view and understand the image of the part to be cut remote from the cutting machine.

Abstract: A device is provided for removal of a layer, such as a label, from a cylindrical surface of an object. The device includes a guide, a cutting instrument, and a base connecting the guide and the cutting instrument. The guide and the cutting instrument are separated by a distance defined by the base, and the cutting instrument is positioned to shave along the object's surface to remove the layer, when the surface of the object is rotated against the cutting instrument and against the guide.

Abstract: A die stamping system includes an upper die, a sliding block, a lower stripper, a die holder connected to the lower stripper, and a lower die-set moveably connected to the die holder. The sliding block includes a body with a wedge-shaped head facing down, a punch connected to the body, and two arms on opposite sides of the body, respectively. The lower stripper matches the upper die-set and has an aperture for passage of the punch therethrough. The die holder is connected to the lower stripper and includes an opening for passage of the body therethrough, and a first notch receiving the two arms. The first notch is larger than the arms. The lower die-set is movably connected to the die holder and includes a wedge-shaped padding block facing up and supporting the wedge-shaped head of the body.

Abstract: A knife assembly (10) particularly adapted for coupling with an extruder barrel (26) is provided having a knife shaft (16) supporting a knife unit (14), with the knife shaft (16) axially rotatable and axially shiftable through fore and aft limits. The assembly (10) may be adjusted during operation without interrupting the axially rotation of shaft (16), using adjustment mechanism (24) located in a safely remote position from knife unit (14). The preferred assembly (10) includes axial shift limiting structure (114, 116, 124) serving to limit the extent of fore and aft axial movement of shaft (16). The mechanism (24) allows fine adjustment of the position of knife unit (14) relative to the extruder barrel (26), and also permits monitoring of the wear of knife unit (14).

Abstract: A cutter blade movably in a radial direction of a wafer is pressed for biasing to an outer circumferential edge of the semiconductor wafer. Simultaneously, the pushing biasing force of the cutter blade is controlled constant with automatic regulation corresponding to a traveling speed variation of the cutter blade, so that effect of a centrifugal force that works at the time of rotating travel of the cutter blade may not vary a pushing biasing force of the cutter blade. As a result, a contact pressure of the cutter blade to the outer circumferential edge of the semiconductor wafer is maintained stable.

Abstract: A punching device includes: a base including a die part that has a top wall; an abutting member connected to the base; a punch supported on the base, movable relative to the die part and the abutting member between upper and lower positions; and an ejecting unit supported on the base and including a non-compressible ejecting element disposed above and adjacent to the top wall of the die part. The punch is movable relative to the ejecting unit at least during movement of the punch from a middle position to the lower position. The ejecting unit abuts against the abutting member at least when the punch is disposed at the upper position.

Abstract: A material cutting machine has a tool mount support mounted for reciprocal movement and a tool mount supported by the tool mount support. A driver, such as a pneumatic cylinder, selectively advances and retracts the tool mount support. A control system is operatively coupled to the driver for setting the advancement force of the tool mount support when a tool supported by said tool mount contacts a workpiece, such as the edge or surface of a moving strip. In this way, the depth of cut of the tool is controlled by tool advancement force rather than by accurate positioning of the tool. In one embodiment, the tool mount support may have a head and a base and a resilient member resiliently coupling the head to the base to provide a damped resilience. With this embodiment, a transient spike in the reaction force which may result, for example, from a hard spot in the material, causes the tool to momentarily deflect.

Abstract: The invention relates to a cutting device for a film of an endless web, which includes at least one blade for severing the film. A blade holder which receives and fixes the blade thereto is disposed on a base ring. The base ring in turn, is rotatably supported on a flange element. The blade is disposed in the blade holder in such a way that upon a rotation of the base ring, severing of the film by the blade is effected.

Abstract: A punching device comprises a pushing pole, an adjusting portion, a supporting portion, and a spring. The pushing pole comprises a first threaded end and a second threaded end. The adjusting portion defines a screw hole therein, through which the adjusting portion is fixed to the first end of the pushing pole. The supporting portion is located on the pushing pole, with the pushing pole passing through a through hole in the supporting portion. The spring is disposed around the pushing pole, with two ends respectively abutting against the adjusting portion and the supporting portion.

Abstract: A lid for a storage device having a storage film is provided. The lid has a lid body and a cutting member having a cutting surface. The cutting member is movable between a first position in which the cutting surface is remote from the storage film and a second position in which the cutting surface is in contact with the storage film.

Abstract: A punch for making a decorative design in a sheet medium having a body formed with a fissure for receiving the sheet media, a cutter axially movable within the body and a die secured in the body for engaging with the cutter. The cutter has a first edge for cutting along at least a portion of a periphery of the decorative design, leaving at least another portion of the decorative design uncut. The cutter has at least one second edge within the first edge for cutting a second element within the decorative design, such that the resulting decorative design in the sheet media may be folded upwards from the sheet media along the portion of the decorative design cut by the first edge and where the portion of the design that is folded upward contains the second element cut by the second edge.

Abstract: Steel reinforced tire fabrics are cut with long rigid bar blades, circular disc blades and disc and anvil blades. All of these blades may have an open relatively deep slot spaced close to the cutting edge that creates a resilient cantilevered spring element that includes the cutting edge. In response to cutting forces, the spring element will deflect and form a concave crossover area that improves cutting. A supporting material, particularly a precompressed supporting material, such as a precompressed or stretched polyurethane strip may be inserted into the slot. The supporting material limits or reduces the deflection of the spring element so that the yield strength of the spring element is not exceeded and it returns to its original position when the forces are removed. A precompressed supporting material exerts an outward force on the spring element. A polyurethane strip may be precompressed by stretching it before it is inserted into the slot.

Abstract: A compliance device having a housing, a support block coupled to the housing and movable relative to the housing along a linear axis, and a tool holder coupled to the support block and rotatable relative to the support block about a rotational axis. The compliance device is further incorporated into a trimming assembly for trimming flash from a workpiece. The trimming assembly includes a positioning mechanism and the compliance device is coupled to the positioning mechanism.

Abstract: A chamfer cutting device for cuffing packaging materials comprises a die and a knife part which has a plurality of knives. The die can be moved toward the knife part in order to carry out a cut. The knives are arranged individually in the knife part in a force-dependent manner in such a way that their position with respect to the tool plate varies in a defined way as a function of the force produced by contact with the packaging material or the die. In the event of contact between the knife and the die, a force acts on the knife which does not exceed a predefined maximum force. The chamfer cutting device has the advantage that the die can be guided right up to the knives.

Abstract: A blow molded container (10) having a trimmed nonround opening (12) is blow molded from a preform (36) and then positioned by a positioner (50) of a nonround trimmer (16) that includes a rotary driven arm assembly (56) having a knife holder (60). A guide (66) guides the knife holder (60) in a nonround path to perform the trimming.

Abstract: A cutting apparatus for cutting a sheet material is provided. The cutting apparatus includes a platform; a rail structure secured onto the platform; a sliding member sliding along the rail structure; a cutting member movably engaging with and carried by the sliding member to pass through and cut the sheet material sustained on the platform; and an adjusting member. The adjusting member can urge the cutting member to move relative to the sliding member so as to contact with the sheet material in response to an external force, and return the cutting member to move relative to the sliding member so as to release the cut sheet material manually or automatically.

Abstract: A slideable hole punch, having an upper seat, at least one drill set and a lower seat. The upper seat has a slide track allowing one slide member to move thereon. The upper seat is fitted over the lower seat. The lower seat accommodates the drill set and has an internal slot. The drill set is disposed between the upper and lower seats. A paper slot is formed between the upper and lower seats. Thereby, paper can be disposed in the paper slot and slide along the slide track by the slide member. The slide member can then press upon the drill set to perforate through the paper to form holes with desired shapes and distances.

Abstract: A film cutter is provided for use in an industrial process in which a vertical blade and a horizontal blade interact. The vertical blade is mounted to move slidingly in a vertical plane and an end of the vertical blade rests upon the horizontal blade. The horizontal blade is mounted at an acute angle to the vertical blade. In the cutting process, the horizontal blade is moved in a direction that is perpendicular to the vertical blade so as to maintain the acute angle between the cutting edges substantially constant while the cutting intersection moves along the blade length.

Abstract: There is provided an optical recording medium-manufacturing apparatus that is capable of avoiding breakage of a substrate while avoiding formation of a central hole off-center with respect to the substrate. A control section causes the vertical movement section to move an ultrasonic horn in directions toward and away from the cutting edge of a punching blade section to thereby cause the ultrasonic horn to press the disk-shaped substrate and at the same cause an ultrasonic generator to perform ultrasonic vibration at least from a time point at which the disk-shaped substrate is brought into contact with the cutting edge of the punching blade section to a time point at which the punching of the central hole is completed.

Abstract: There is provided a cut-forming machine which is capable of preventing movement of a substrate caused by movement of a cut-forming blade section, a vertical movement mechanism moves at least one of a table for supporting a disk-shaped substrate and a cut-forming blade section toward the other of them, thereby pushing the cut-forming blade section into a light transmission layer of the substrate. A spring urges an urging portion disposed in a central portion of the cut-forming blade section, from at least a time point of completion of pushing the cut-forming blade section into the light transmission layer to a time point of removal of the cut-forming blade section from the light transmission layer, thereby causing the urging portion to urge a central portion of the disk-shaped substrate toward the table.

Abstract: A table saw having a rotation structure includes a work table, a suspension rod, a swing seat, a rotation seat, a push lever, two torsion springs, and a threaded rod. When the threaded rod is rotated, the push lever is displaced horizontally to push the rotation seat to rotate, so that the circular blade is moved upward, thereby adjusting the cutting height of the circular blade. Thus, the push lever is urged by the elastic force of the two torsion springs, so that the push lever is closely and rigidly combined with the threaded rod, thereby eliminating the clearance between the push lever and the threaded rod, so that the cutting height of the circular blade is adjusted exactly and precisely, thereby enhancing the cutting efficiency of the table saw.

Abstract: A method and apparatus for chopping long unwound items like fiber, fiber strands, yarn, etc. The chopper has a backup roll, a blade roll and a biasing system for forcing the backup roll and the blade roll together at a desired force during set up and operation. The biasing system contains a mechanism such as a slip clutch or a limited torque stepping motor for maintaining a substantially constant biasing force at set up and during operation while allowing the rolls to separate slightly to pass a temporary thicker feed without recoil that currently shortens blade and backup roll working layer life.

Abstract: A cutting tool holder for holding a cutting member, which is attached to a drive unit for driving the cutting member. A first elastic member is elastically deformable in a first direction. A second elastic member is elastically deformable in a second direction different from the first direction. An elastic connection member elastically connects the first and second elastic members. A first attachment member is disposed in the first elastic member to be connected to the drive unit. A second attachment member is disposed in the second elastic member to attach the cutting member.

Abstract: A cutter for self-adhesive labels has a top part and a bottom part and a feeding gap between the top part and the bottom part. The cutter includes further a cutting mechanism having a blade and coupled to one of the top part and the bottom part. Further, the cutter has a transport and guiding device for the labels, wherein the transport and guiding device includes a transport roll located opposite the cutting mechanism. The feeding gap receives an adhesive paper or label sheet and the transport roll pulls the adhesive paper or label sheet through the feeding gap. The adhesive paper or label sheet passes between the cutting mechanism and the transport roll, and the blade cuts the adhesive paper or label sheet against a curved surface of the transport roll.

Abstract: Steel reinforced tire fabrics are cut with long rigid bar blades, circular disc blades sand disc and anvil blades. All of these blades may have an open relatively deep slot spaced close to the cutting edge that creates a resilient cantilevered spring element that includes the cutting edge. In response to cutting forces, the spring element will deflect and form a concave crossover area that improves cutting. A supporting material, particularly a precompressed supporting material, such as a precompressed or stretched polyurethane strip may be inserted into the slot. The supporting material limits or reduces the deflection of the spring element so that the yield strength of the spring element is not exceeded and it returns to its original position when the forces are removed. A precompressed supporting material exerts an outward force on the spring element. A polyurethane strip may be precompressed by stretching it before it is inserted into the slot.

Abstract: A cutter assembly, comprising a first cutting member having a first cutting edge, a second cutting member having a second cutting edge, wherein the first and the second cutting edges are disposed in space relative to one another, and a means for biasing the first and second cutting members toward one another to cause a point of cutting contact between the first and the second cutting edges, where the point of cutting contact moves along the first and the second cutting edges over time.

Abstract: A cutting device for shingles that cuts shingles at angles. Several blades, each on pressure plates, are forced into engagement with shingles by rollers that engage one side of the plates.

Abstract: This invention relates to a rotary cutoff apparatus, which permits easy speed control without needing high-level skill or technique and also allows ready replacement of its anvil member. The apparatus is provided with a knife cylinder, which has a knife arranged on its outer circumferential surface and is rotatably supported, and an anvil member with which a free edge of the knife can be brought into contact upon rotation of the knife cylinder, whereby a travelling band-shaped sheet is nipped between the knife and the anvil member and is hence cut off. The knife is supported on the knife cylinder via a spring having spring force sufficient to bear cutting force required to cut off the band-shaped sheet so that the knife is displaceable in a loaded direction upon cutting off the band-shaped sheet. The rotary cutoff apparatus according to the present invention can be arranged, for example, in a production line for a band-shaped sheet material such as a corrugated fiberboard sheet.

Abstract: The present invention relates to a shear blade assembly for a shearing system. The shear blade assembly includes an upper shear blade and a lower shear blade. The top surface of the lower shear blade is inclined downwardly at an angle of between 0.2 and 0.5 degrees to the horizontal. The bottom surface of the upper shear blade is raked relative to the horizontal, longitudinally of the blades.

Abstract: A machine tool has a work table which defines a working surface and has a cutting tool which is attached to and movable with respect to the work table. The position of the cutting tool with respect to the working surface is controlled by a mechanism which elevates the cutting tool with respect to the working surface and angulates the cutting tool with respect to the working surface. The cutting tool is mounted to a support plate which is pivotably attached to the work table. The elevating mechanism includes a threaded rod and a nut which engages a pivoting link. The pivoting link also engages the cutting tool. Rotation of the threaded rod pivots the link which in turn raises and lowers the cutting tool. A spring biases the cutting tool towards its lower position to remove play between the components. The angulating mechanism includes a lever, two cams and a locking rod. Rotation of the lever moves the locking rod longitudinally due to the action between the two cams.

Abstract: A quick-extraction punch-holder adaptor for converting punching machines from a single-punch to a multiple-punch configuration, connectable to a conventional turret of a punching machine, comprises a cylindrical body crossed by a plurality of punch accommodation receptacles, a selection device rotatably mounted at the end of the cylindrical body and provided, at a lower face, with a tooth for contact with the head of each selected punch and elastic elements, circumferentially interposed between the selection device and the cylindrical body, and being loadable by compression to contrast the active stroke and produce the return of the punches.

Abstract: An apparatus for slitting a sheet of web material has an at least one first fixed blade member and axially displaceable at least one second blade member. The axially displaceable second blade member is biased by an elastomeric biasing member that provides a continuous and uniform contact force with a face of the second blade member. The elastomeric biasing member is restrained from axial movement by a bonded ring member.

Abstract: A high-speed shear with a knife, particularly a chisel-type knife with a knife edge, arranged on at least one of two oppositely arranged drums, wherein the knife can be accelerated to the feeding speed of the rolled strip and the drums can be adjusted relative to each other for carrying out a cut. At least one drive unit provided for the drums serves to accelerate the drums to the speed of the rolled strip to be cut and at least one of the drums may be provided with a separately controllable adjusting device. The chisel-type knife of the knife drum is mounted so as to protrude from the cutting circle towards the anvil or the surface portion of the second drum acting as an anvil and to mount the chisel-type knife of the knife drum so as to be resiliently supported against a predetermined restoring force.

Abstract: A sheet cutter has a fixed blade and a movable blade. The fixed blade has a straight edge extending in a lateral direction with respect to a longitudinal direction of a sheet to be cut, and the movable blade is provided so as to be moved in the longitudinal direction. The movable blade has an edge on a side of a blade end portion extending in a direction making a first angle with the straight edge of the fixed blade. The edge of the movable blade is pressed against the edge of the fixed blade.

Abstract: A letter opener, especially intended for manual operation, is proposed, which can open a conventional envelope without producing any waste. For this purpose, it has a round knife (3), mounted by way of spring-generated pretension (7) between two rails (4, 40), the diameter of the knife being slightly smaller than twice the smallest possible distance between the axis of the knife and the letter support surface (1).

Abstract: A paper cutter having a paper stand, a pair of arms of identical length attached to the paper stand defining a contacting position and a separating position, a guide rail connected to the pair of arms such that the guide rail is parallel to the paper stand, a slider slidably attached to the guide rail. The slider has a rotary blade fixed on a holder, the blade being capable of being moved up and down within the slider against a spring, the blade exposed by being pushed down when the slider is in the contacting position, and a stopper, with a top end and a heavy end, which rotates automatically on a shaft due to its heavy end, hooking the top end on a projection provided on the slider to prevent the rotary blade from being projected from the slider when the guide rail is rotated to the other than the contacting position.