Abstract: The invention relates to an ejector device for an injection-molding machine for plastics, having at least one ejector pin, which can be moved toward the mold and away from the latter through the center of a moveable die clamping plate by an actuator. In this arrangement, the actuator provided is a linear motor (21), which is arranged outside the central axis (I) on the moveable clamping plate (11) , and bar-shaped force-transmission elements (30), by means of which the linear motor can be brought into operative connection with the ejector pin (41), are provided.

Abstract: A mold for forming blocks with at least one textured surface, the mold comprising a structure defining a cavity open at opposite ends thereof for receiving a block forming material at one of the open ends and discharging a block formed from the block forming material at the other of the open ends; and a continuous web surrounding at least a portion of the structure and movable relative to the structure for acting on the block forming material received within the cavity to impart a texture to a surface of the block, the web being mounted to move around the portion of the structure when the block is discharged from the cavity.

Abstract: An injection-molded plastic part cooling tube has an extruded cylindrically shaped tube with an inside surface and an outside surface. An extruded cooling channel is disposed inside the cylindrically shaped tube, between the inside surface and the outside surface. A method for forming an injection-molded-plastic-part cooling tube includes the step of extruding a hollow aluminum tube having an inside surface, an outside surface, and at least one cooling channel in the hollow aluminum tube between the inside surface and the outside surface. Alternative cooling tubes include a tubular porous insert for vacuum forming molded articles.

Abstract: A method of manufacturing a building product from a mix (6) including particulate material and a thermoplastic binder which comprises heating the mix at least to a temperature at which the thermoplastic binder in the mix liquefies, subjecting the heated thermoplastic mix to a pressing action that shapes the heated mix, and cooling the shaped heated thermoplastic mix to solidify the thermoplastic binder and form the product (FIG. 4).

Abstract: An ejector system for use in an injection molding machine comprises a plurality of rack gears and pinions gears that provide active alignment of plates within the ejector system. As unequal force is experienced in ejecting a molded item, the rack and pinion gears distribute the force to other areas of the ejector system plate, maintaining proper alignment of the plates within the ejector system.

Abstract: The present invention includes an improved ejector sleeve (5) having thinner side-walls than prior sleeves. The sleeves generally include a ring (31) for mounting the sleeve, a central bore (42) for receiving a core pin (1), a tube portion extending from the ring to a tube end portion. The side-walls defining the tube end portion have a thickness of less than forty thousandths, and preferably thirty thousandths of an inch. Preferably, the coated ejector sleeve is provided in which a thin, lubricous coating of nickel, chromium or alloys of chromium or nickel is applied to at least a portion of the sleeve. The coating is applied in thickness of less than 0.0001 inch which improves the wear characteristics of the pins and sleeves as well as allowing the coated pins and sleeves to be stocked and used as nominal thickness parts.

Abstract: An optoelectronic component has a lens that is formed in the surface of an encapsulant surrounding a semiconductor diode element. With respect to emitters, the lens reduces internal reflection and reduces dispersion to increase overall efficiency. With respect to detectors, the lens focuses photons on the active area of the detector, increasing detector sensitivity, which allows a detector having a reduced size and reduced cost for a given application. The lens portion of the encapsulant is generally non-protruding from the surrounding portions of the encapsulant reducing contact surface pressure caused by the optoelectronic component. This non-protruding lens is particularly useful in pulse oximetry sensor applications. The lens is advantageously formed with a contoured-tip ejector pin incorporated into the encapsulant transfer mold, and the lens shape facilitates mold release.

Abstract: This disclosure is directed to an adjustable knockout rod for use in conjunction with injection molding machines. The knock-out rod disclosed herein is preferably formed of a round bar having a plurality of annular notches or undercuts formed at uniform intervals along the length of the bar. The knock-out rod passes through a stationary platen and is retained in position relative to the stationary platen by a split collar. The split collar is designed to be inserted into the stationary platen in more than one orientation thereby effecting adjustment of the knock-out rod a distance and interval less than the distance between the adjacent notches on the rod. Additionally, the quick adjusting knockout rod disclosed herein is provided with means for fine adjustment of the overall length of the rod.

Abstract: An ejector housing cover plate for an injection mold system having an upper stationary portion and a lower movable portion. The upper portion has a support member and a cavity core, while the lower portion has a frame defining an interior opening, support member and a frame core. An ejector system is positioned within the opening and is movable to eject newly molded products when a molded product has been formed. The opening in the frame can result in the collection of dust, moisture and other foreign materials inside the opening and the possible damage to the mold or ejector system, so an ejector system cover plate is provided. The cover plate covers the opening during operation of the system and when the system is inactive or stored.

Abstract: A mold assembly (100) formed of a pair of molds (102, 104) and a pair of release plates (118, 120). The molds (102, 104) have holes (126) which extend from outer surfaces into the mold cavities (106). The release plates (118, 120) have pins (122, 124) which pass into the holes (126, 128). When molding is finished, the molds (102, 104) are moved toward the release plates (118, 120). The pins (122, 124) contact the molded article(s) (134) and hold them in position as the molds (102, 104) are withdrawn.

Abstract: A molded part ejection tystem (103) includes a drive mechanism having a reversible servomotor (240). The drive mechanism for the ejection system includes a cam-and-follower arrangement whereby a circular cam member (252) is driven by the servomotor (240) through a drive shaft (250) that is connected with the cam member (252) and is offset from the center of the circular cam track (254). A cam follower (260) connected with an ejector drive rod (238), and the cam follower (260) rides in the cam track (254) to cause linear movement of the ejector drive rod (238) as the cam follower (260) follows the circular cam through its non-circular path of motion. Rotation of the servomotor (240) in one direction of rotation operates the part ejection system, while rotation of the servomotor in the opposite direction of rotation provides power to another portion of the machine during another portion of a molding machine operating cycle, such as a core-pull system.

Abstract: An ejector system for use in an injection molding machine comprises a plurality of rack gears and pinions gears that provide active alignment of plates within the ejector system. As unequal force is experienced in ejecting a molded item, the rack and pinion gears distribute the force to other areas of the ejector system plate, maintaining proper alignment of the plates within the ejector system.

Abstract: An apparatus for repairing or refurbishing thermoplastic drums. A damaged drum, or at least a damaged portion thereof, is heated until it reaches a softened state and is then drawn over a template, or mold, having the substantially the same shape and size of an undamaged drum. The drum is allowed to cool sufficiently to return to its hardened state, whereby it substantially assumes the shape of the template. The refurbished drum is then removed from the template and is essentially ready to be used again.

Abstract: A release mechanism operating to release molded articles from a third mold portion includes a guide coupled to the second mold portion forming a cam track. A cam follower coupled to the surfaces of the third mold portion, which are holding the molded articles, is engaged in the cam track when the second and third mold portions are within a pre-selected distance of each other. The cam follower interacts with the cam track to cause some initial movement of the surfaces holding the molded articles to a pre-release position for the holding surfaces so that the molded articles are loosely retained by the holding surfaces. A power operator, carried by the third mold portion and coupled to the article holding surfaces, is responsive to a signal to move the article holding surfaces from the pre-release position to a full release position when a molded article receiver is suitably positioned to receive the molded articles. The molded article receiver includes receiver tubes for receiving the molded articles.

Abstract: The present invention provides a kit (200) for producing a high quality sushi product with uniformity and at a high rate of production. The kit (200) includes a Nigiri Sushi mold (10, 110) and a California Sushi Roll apparatus (54, 154.) In a preferred embodiment, the kit (200) includes a traditional Japanese bento box (18,20) that houses both the Nigiri Sushi mold (10, 110) and California Sushi Roll (54, 154.) The Nigiri Sushi mold (10, 110) is made up of a mold (12, 112) having several indentations (28, 128) for supporting the preferred ingredients. The Nigiri mold (12, 112) is joined with the plate (14, 114) and is placed in the bottom half of the Japanese bento box (18) to form the lower portion of the Sushi kit (200) of the present invention. The apparatus (54, 154) used to form the California Rolls sits atop an inverted Nigiri mold (12, 112) with plate (14, 114) and includes a roller sheet (56, 156) that is flexibly attached to a base plate (64, 164.

Abstract: Mold apparatus and method of production and ejection of molded wood strand three-dimensionally curved articles of manufacture, molded from a loosely felted flake mat, using an ejector pin assembly within said mold apparatus having ejector pins with pin head diameters of at least about 0.750 inches or greater, that exert a loaded ejector pin pressure of from approximately about 100 psi to about 1000 psi, to eject the molded wood strand article from the mold apparatus without causing excessive indentation and densification within the mat during mold processing.

Abstract: Apparatus for manufacturing molded products with an EMI/RFI/ESD shield. The apparatus includes shaping apparatus for automatically shaping a mesh blank into a mesh insert on a fixture, and a robot for removing the insert from the fixture and placing it in a molding machine in preparation for molding the insert into a molded product. Also disclosed is a method for manufacturing molded products involving the steps of automatically forming the blank into a mesh insert and automatically transferring the insert to a molding machine using a robot. A holding tool may be provided for the robot to use in transferring the insert to the molding machine.

Abstract: An improved take-off device for an injection molding machine that includes an extensible sleeve for extending a suction channel during transfer of parts from the mold core assembly to the take-off device, the tube being retractable after the parts have been transferred.

Abstract: A robotic method and apparatus for removing finished parts from the trim press of a thermoforming system including a pick and place tool mechanism moveable on at least a two-axis gantry mechanism arranged adjacent the trim press, the pick and place tool being moveable into and out of the trim press to acquire and remove finished thermoformed parts from the trim press. Movement of the pick and place tool is synchronized with the trim press cycle. The present method may include a conveyance system mounted adjacent the pick and place mechanism for placing and stacking the finished thermoformed parts thereon once such parts are removed from the trim press.

Abstract: An arrangement (2) for a two-stage ejector (3), which has a follow-on action, capable of installation centrally in a moulding tool (1). The injector has a rear ejector part (5) exhibiting connecting means (4) for attachment of the injector (3) to an injection moulding machine. The rear ejector part, is capable of detachable attachment to the remaining part (6) of the ejector (3).

Abstract: A molded article ejecting device includes proximate and distal ejector plates which are movable relative to a stationary plate of an injection molding apparatus, an ejector pin which is positioned by and which is moved with the ejector plates to knock out a molded article from the stationary plate, and an ejector rod which is actuated by means of an actuator to perform a to-and-fro movement and which has a head portion that is detachably coupled to the distal ejector plate by a coupler mechanism in a frictional engagement that is maintained when the ejector rod is set in the to-and-fro movement.

Abstract: An improved mold ejector is provided. The mold ejector can be a poppet valve or an ejector pin. The surface of the bore of the ejector opposite the stem of the ejector is interrupted by at least one relief. The relief allows foreign particles that are trapped between the ejector stem and the bore to pass away from the ejector. The relief can also be defined on the surface of the stem. The relief also reduces the frictional forces between the ejector and the bore.

Abstract: In a data registration method for a molding system including a molding machine and a take-out machine, after completion of operation of setting molding conditions for the molding machine and operation of setting take-out conditions for the take-out machine, data of the molding conditions and data of the take-out conditions are registered in a memory unit provided in the molding machine, while being interrelated.

Abstract: An apparatus and method for removing molded parts from a mold having cores arranged in at least two columns on a core plate. A pivoting part-removal device, preferably attached to the core plate between columns of cores, pivots parts from a column of cores to a chute located between columns of cores. The removal device has at least one pivoting arm with a part-gripping suction cup. The chute maintains an orientation of parts as they move along the chute. Parts from two columns of cores can be deposited in an interlaced arrangement into one chute. In one embodiment, the parts are translated as they are pivoted to facilitate the interlacing when the cores in adjacent columns are not staggered. In another embodiment, used when the part sidewalls are high with a low draft angle, the parts are moved straight off the cores a distance before pivoting them.

Abstract: A method and apparatus for repairing or refurbishing thermoplastic drums, by which a damaged drum, or at least a damaged portion thereof, is heated until it reaches a softened state and is then drawn over a template, or mold, having the substantially the same shape and size of an undamaged drum. The drum is allowed to cool sufficiently to return to its hardened state, whereby it substantially assumes the shape of the template. The refurbished drum is then removed from the template and is essentially ready to be used again.

Abstract: An unloader is used to remove a lugged strip from a press. The unloader has a pair of spaced, adjacent horizontal tines for pulling the lugged strip out of the press and the press lug molds and onto the unloader. To assist in removing the lugged strip from the press, at least one tine has a conveyor belt mounted on its upper surface. The conveyor belt is run in one direction to pull the strip onto the unloader and in the opposing direction to assist with removing the cured strip from the unloader.

Abstract: An ejector device (200) for ejecting articles for injection molding machines for plastic materials comprising a movable mold-holding plate (13) supporting a mold half (20) defining a profile whereon a molded article (21) is formed, and moved by a double toggle mechanism comprising connecting rods (18) connected to the movable mold-holding plate (13); the device (200) for ejecting articles comprising a movable ejector plate (3) supported in translation by means of supporting columns (4) fixed to the movable mold-holding plate (13), and a pin (2) connected to the movable ejector plate (3) and acting on an ejector table (1) arranged into a mold half cavity (51) to favor ejection of the molded article (21), the movable ejector plate (3) being moved by means of lever mechanism driven by a ball screw (35) actuated by an electric motor (40).

Abstract: A helical gear is disclosed that is formed by an injection molding process in which the mold cavity is formed of mirror finished hardened stainless steel. The helical gear is disclosed in a gear box that entirely encase the gears, and may be integral with the housing of the toy. Furthermore, an “L” axle for gears is disclosed that provides a straight shaft portion that extends through the axle bearing aligned with the centerline of the gear and a bent portion that is seated in a slot recess in the wall of the gear box.

Abstract: The present invention provides a molding system as well as a method for encapsulating semiconductor packages, wherein a cavity plate is kept at a desired temperature during molding. The system includes a mold comprising a first mold piece and a second mold piece adapted to define a mold cavity for enclosing one or more semiconductor devices for molding, and a cavity plate adapted for mounting in the cavity to introduce encapsulation material to the semiconductor device(s). The system also includes retaining means adapted selectively to hold the cavity plate against the first mold piece or the second mold piece whereby to maintain the cavity plate at the desired temperature.

Abstract: A die clamping apparatus including a movable plate which is in connection with a pushing-out pin which is projected from and retracted to a moving die and which is held movably with respect to a moving die plate, a clamp member for obtaining a constraint of the movable member, an air cylinder and a hook member. Only a movement of the movable member is constraint by the air cylinder with respect to the moving die plate when the latter is moved in a die opening direction from a die opening limit position, so that a resultant relative movement between the movable plate and the moving die plate, which causes the pushing-out pin to be projected from the moving die, resulting in a removal of a molded product, while the constraint of the movable member prevents the moving die plate from being moved in the die closing direction when the moving die plate in the die opening limit position is under non clamping condition.

Abstract: A plastic injection molding machine includes a rod having an end engaged with a slide member located beside the lower mold, and a position block connected to the upper mold. A pin is movably inserted in two respective inclined holes in the position block and the slide member so that the threaded section on the tip end of the rod is moved into the cavity with the movement of the slide member. The rod is located between two side members each have a threaded semi-circular recess. Another threaded section has the same threads of the thread section on the tip end of the rod is engaged with the two threaded semi-circular recesses so that the rod is rotatably withdrawn from the cavity smoothly when the rod is rotated by a motor.

Abstract: An undercut release component having an end configured for molding a part having an undercut is disclosed wherein the configured end disengages from the molded undercut by traveling in a 3-axis path. A process for providing undercut release in a mold is also disclosed.

Abstract: A resin encapsulation mold of the present invention comprises a lower mold, which is mounted on a lead frame, includes an indentation into which a semiconductor device is placed, and forms a gate through which resin is injected; an upper mold, in which an indentation is formed opposite the indentation of the lower mold to configure a cavity for holding the semiconductor device; a plurality of ejection pins, which protrude from the respective bottoms of the indentation of the upper mold and the indentation of the lower mold into a resin package body formed by injecting the resin from the gate into the cavity, and eject the resin package body; a vertical drive mechanism, which brings into contact and separates the upper mold and the lower mold; and protrusion adjustment means for adjusting the amount of protrusion of the respective ends of the plurality of ejection pins.

Abstract: Improved lifter (32) for injection molding apparatus and method of use thereof are disclosed. To inhibit the unsightly blemishes that may be formed in plastic parts wherein the lifter (32) comprises a leading edge (44) that is perpendicularly oriented relative to the longitudinal axis of the molded part, a lifter plate is provided wherein the leading edge (44) thereof is obliquely angled relative to the longitudinal axis of the molded part.

Abstract: A device for producing disposable lenses providing a concave mold and a convex mold for each lens, filing the concave mold with liquid starting material for the lens, and positioning the convex mold so as to enclose the starting material includes a first carousel, a first station, which is arranged along the first carousel, for depositing the concave mold at a set position on the carousel, a second station for filling the deposited concave mold with starting material for a lens, a third station for depositing the convex mold so as to enclose the starting material, and a fourth station for removing the assembly having concave mold and convex mold with enclosed starting material the first carousel.

Abstract: A mold for manufacturing semiconductor packages, which allows leadframes to be easily separated from a top mold section after a molding process by utilizing eject pins therein. The mold includes a bottom mold section having housing parts on the upper surface so as to allow leadframes to be placed in a flat state therein, and a top mold formed with transports therethrough. The top mold also incorporates runners formed along a lower surface with connections to the transports to introduce encapsulation material into select regions. A plurality of gates and cavities for molding the semiconductor packages are in flow communication. The eject pins are reciprocally mounted in the top mold section contiguous with the runners thereof to facilitate separation of the leadframes from the top mold.

Abstract: A concrete product molding machine supports a vibratable mold having an open top and an open bottom. A stripper head is movable from a position above the mold to an intermediate position ready to strip the molded product from the mold and then on to a lower position in which it has. A pallet receiver is movable from a lower position to a mold closing position in which a pallet it carries closes the bottom of the mold. Disengageable linking mechanism is provided for coupling the striper head and pallet receiver frame for conjoint travel in movement of the stripper head through the mold. A connector assembly connects with a pallet receiver lift arm and incorporates an actuator for varying the position of the upper end of the lift arm and thereby varying the vertical position of the pallet receiver.

Abstract: An optoelectronic component has a lens that is formed in the surface of an encapsulant surrounding a semiconductor diode element. With respect to emitters, the lens reduces internal reflection and reduces dispersion to increase overall efficiency. With respect to detectors, the lens focuses photons on the active area of the detector, increasing detector sensitivity, which allows a detector having a reduced size and reduced cost for a given application. The lens portion of the encapsulant is generally non-protruding from the surrounding portions of the encapsulant reducing contact surface pressure caused by the optoelectronic component. This non-protruding lens is particularly useful in pulse oximetry sensor applications. The lens is advantageously formed with a contoured-tip ejector pin incorporated into the encapsulant transfer mold, and the lens shape facilitates mold release.

Abstract: The invention relates to a mould container for an apparatus for manufacturing green bricks from clay for the brick manufacturing industry, wherein mould containers are arranged on a circulating conveyor, which mould containers comprise a number of mould cavities open to the top, wherein the mould container comprises a fixed mould container part with mould cavities and an exchangeable mould container part such that green bricks of differing dimensions can be made simultaneously.

Abstract: Post-mold cooling of injection molded plastic articles such as preforms is achieved by transferring the articles directly from the mold cavities onto cooling cores carried by a take-out plate. The molded articles are supported on the cooling cores until they become sufficiently frozen that they can be stripped from the cores.

Abstract: A mold base system for injection molding machines comprises two cast mold bases each with interior lugs. The lugs of each mold base removeably hold an insert. The inserts are machined to define a cavity that is the negative of the part to be molded. The inserts can be changed to suit different parts without changing the mold bases, which can stay on the injection molding machine indefinitely. Ribs connect the lugs to the mold base outside walls. Two ribs and an outside wall define a pocket that provides access to an insert. The ribs are notched to enable coolant lines to be routed without interference inside the mold base. The mold base system further comprises an ejector plate and a cap. The cap is changeable to suit different configurations of the ejector pins without changing the ejector plate.

Abstract: The invention relates to a device for removing injection moulded parts from the mould of an injection moulding machine, especially for plastics, provided with a moveable and a fixed tool mounting plate. The inventive device comprises a drive unit which enables an actuating unit connected to a spindle (21) to be moved both towards and away from the mould in a linear manner. An engaging element (40) is also provided to enable the spindle (21) to be displaced axially. The invention is characterized in that a toothed disk (22) is secured to one end of the spindle (21), whereby the diameter thereof (D) is greater than the outer diameter (d) of the spindle (21). The invention is further characterized in that the toothed disk (22) corresponds to a tubular component (31) which can be driven by the drive unit (61) and which surrounds the spindle (21) in a free moving manner. The invention is also characterized in that the engaging element (40) is connected to the moveable tool plate (11).

Abstract: A shuttle blow molding machine having two groups of mold units located on opposite sides of a series of workstations spaced along a horizontal workstation path. Each mold unit includes a mold that reciprocates in a direction transverse to the workstation path between a retracted position that is spaced from the workstation path and an extended position aligned with the workstation path. The mold units within each group are located in side-by-side relation adjacent each other and each group is indexed as a single unit along a path parallel to the workstation path. The transverse motion of the molds between their retracted and extended positions allows one group to be retracted out of the way while the other group advances through the workstations.

Abstract: A mold assembly (100) formed of a pair of molds (102, 104) and a pair of release plates (118, 120). The molds (102, 104) have holes (126) which extend from outer surfaces into the mold cavities (106). The release plates (118, 120) have pins (122, 124) which pass into the holes (126, 128). When molding is finished, the molds (102, 104) are moved toward the release plates (118, 120). The pins (122, 124) contact the molded article(s) (134) and hold them in position as the molds (102, 104) are withdrawn.

Abstract: The invention relates to a handling appliance for a plastic injection-moulding machine. The handling appliance includes a gripper for the extraction of injection-moulded plastic parts from the injection-moulding machine. The gripper has at least one gripping element which retains the injection-moulded plastic part by suction during extraction. Furthermore, there are means for providing at the location of the gripping element a vacuum for sucking up the plastic part. The handling appliance according to the invention is characterized in that the said means contain at least one fan which is arranged on the gripper.

Abstract: An apparatus and method for providing delamination-resistant, array type molding of chip laminate packages such that larger chip array block sizes may be employed. An advanced mold die provides multiple wells for the formation of ejector pin tabs to be formed integrally to the mold cap of a chip laminate package. The die further provides for an ejector pin hole to be located at each ejector pin tab such that the ejector pins, when pressed for release of the laminate package from the mold die, bear against the integrally formed pin tabs rather than against the substrate of the chip/substrate assembly. The placement of the ejector pins for bearing against the pin tabs precludes the loading of the interface within the laminate package between the mold cap and the chip/substrate assembly. Substantially reduced delamination of the chip laminate package is achieved allowing for the use of larger chip array block sizes and providing for a substantial reduction in chip laminate package moisture sensitivity.

Abstract: A mold includes a top die and a bottom die moved relative to each other and defining therebetween a cavity for molding a molding of predetermined pattern, and a compacting mechanism adapted to compact the molding in the cavity, the compacting mechanism having a plurality of compacting rods adapted to compact the molding in the cavity, a pressure plate adapted to move the compacting rods into the cavity to compact the molding in the cavity, and a plurality of stop rods adapted to limit the range of movement of the pressure plate toward the bottom die.

Abstract: A modular molding system having: an upper frame assembly configured for receiving a cavity module therein; a lower frame assembly configured for receiving a core module therein, the lower frame assembly including a two-stage master ejector system; a cavity module positioned within the upper frame assembly; and a core module positioned within the lower frame assembly, the core module including a two-stage ejector system having a plurality of ejection elements associated therewith; wherein the core and cavity modules together define a molding cavity for molding a workpiece therein, and wherein the master ejector system is operable to drive the ejection elements of the core module.

Abstract: Method and apparatus for control of an ejector mechanism of a molding machine. A procedure is executed without operator intervention for setting limits for controlling motion of movable members of mold assemblies, the movable members linked to ejector pins communicating with the mold cavity and used to assure molded articles are dislodged from a mold element. The procedure, typically associated with a “set-up” mode of control, operates an ejector mechanism with reduced force to drive the movable members to the extremes of travel thereof, senses a “stalled” condition at each extreme, and causes measured position of each extreme to be recorded. Position values intended for use in normal (program controlled) operation of the molding machine are derived from the recorded position values.

Abstract: A middle liner of a slide guide device for a machine press has a spherical shaped side which fits into a sliding gib attached to a slide. The middle liner slides along a fixed gib at first and second linear surfaces that are at an angle with each other. The combination of self-alignment and smooth movement of the slide is achieved in the presence of an eccentric load acting on the slide. A machine press equipped with such a slide guide device has excellent eccentric load resistance and high working precision. In a further embodiment, a press machine is further equipped with a knockout device having knockout block moving between a pair of guide rails. A plurality of middle liners, each having at least one spherical surface, are positioned between the knockout block and the guide rails. The resulting knockout device provides a stable knockout load with low noise and low energy consumption.