Abstract: An object is to improve the wear resistance of a mold part and improve accuracy of disc substrates. A disc-molding mold comprises a first mold including a first support plate and a first mirror-surface disc attached to the first support plate; and a second mold including a second support plate and a second mirror-surface disc attached to the second support plate. A sliding surface of a mold part disposed on one of the first and second molds is treated by means of low-temperature nitriding. In this case, since the mold part is treated by means of low-temperature nitriding, the wear resistance of the mold part can be improved. In addition, since the treatment temperature is low, even when low-temperature nitriding is performed on a mold part which is complicated in shape, the mold part does not deform, and its dimensional variation can be decreased.

Abstract: An apparatus for molding a mold by pressurizing a foam mixture composed of particles of aggregate, water-soluble binders, and water, and injecting it into a cavity of a heated metal mold that includes a hollow rectangular-parallelepiped body 12 having a bottom plate 14, the bottom plate 14 having an injection hole 13 to inject the foam mixture, a device 10 for containing the foam mixture having functions as a mixing bath to mix particles of aggregate, water-soluble binders, and water, and as a pressurized vessel to inject the foam mixture into the metal mold, and a device 22 for closing and opening the injection hole 13. The apparatus is further provided with a device for measuring a temperature of the particles of aggregate or the foam mixture, the viscosity, and the moisture and a device for communicating gases from the cavity of the metal mold to the outside of the mold so that the particles of aggregate cannot pass through it.

Abstract: A mold used in a manufacturing process of a rotor of an electric motor, the rotor including a rotor core with a plurality of magnet-retaining apertures and a plurality of permanent magnets individually retained in the magnet-retaining apertures of the rotor core, for pouring a resinous material into gaps defined between the magnet-retaining apertures and the permanent magnets. The mold includes a cavity for accommodating the rotor core at a predetermined position, with the rotor core receiving the permanent magnets individually in the magnet-retaining apertures; and a deformation inhibiting surface provided in the cavity and coming into at least local contact with an outer circumferential surface of the rotor core, during a period when the resinous material is poured into the gaps, to inhibit the bulging deformation of the outer circumferential surface.

Abstract: A mold for molding an optical element, in particular using a reaction injection molding method (RIM). The mold comprises a generally circular shaped, mold cavity having a geometrical center and a main plane, a sprue base with a longitudinal axis and a feed connection that makes the sprue base communicate with a feed sill of the mold cavity, the longitudinal axis of the sprue base and the geometrical center of the mold cavity defining a mold symmetry plane orthogonal to the main plane of the mold cavity, which intersection with said main plane defines a mold main axis, characterized in that the longitudinal axis of the sprue base together with a line perpendicular to the main plane of the mold cavity forms an angle ranging from 0 to 30°, preferably from 0 to 15°. Methods of using the mold and objects made thereby are also disclosed.

Abstract: A side gate type injection molding die prevents a weld line from being generated on a molded component made of a resin material to which a brightening agent is added, avoiding inferior appearance. The side gate type injection molding die including a product portion 7, which is a space for molding, and a side gate 8, which is used to inject the material into the product portion 7, in which the side gate 8 is formed so as to have a rectangular transverse cross section in a contact part 9 between the product portion 7 and the side gate 8, is configured so that at least one of corner parts 9e of the transverse cross section formed into a rectangular shape in the contact part 9 of the side gate 8 is formed in a curved shape; and the resin material to which the brightening agent is added is injected into the product portion 7 from the side gate 8 to manufacture a molded component 1.

Abstract: A tape reel assembly comprises a reel hub and flanges coaxially secured to, and extending radially outwardly from, opposite axial ends of the reel hub, respectively, each flange being molded by resin injection molding and having a tapered inside surface sloping down at a fixed taper angle from an inside periphery to an outside periphery thereof. The flange is molded by the use of an injection mold having a mold surface which borders at least a part of a mold cavity for configuration of the tapered inside surface of the flange and is convexly curved to the mold cavity.

Abstract: A rotatable base (100) for a porous pad (500) has openings (126, 130, 134) that provide for improved flow distribution of a liquid in the base (100) across a substrate. The rotatable base (100) can be molded from a two piece mold and the openings (126, 130, 134) can have draft angles to facilitate the molding process.

Abstract: A respiratory mask, a mould for a respiratory mask, as well as to a method for producing a respiratory mask are disclosed, in which manufacturability and usability of respiratory masks are improved. A respiratory mask is disclosed for administering a breathable gas to a patient, the respiratory mask comprising a first component formed from a flexible material and a second component formed from a material that is more rigid than the flexible material, wherein the first component is formed onto the second component by an overmoulding process.

Abstract: The injection mold with a tie bar includes an upper stationary board, a stripping plate, a female board, a male board and a lower stationary plate from top to bottom. The upper stationary plate extends outward to form a projection plate, an accepting hole opened in the projection plate and having a step therein. A tie bar is arranged on the outside of the injection mold and includes a stud, a connecting head and a pole. The stud passes through the accepting hole and is fixed on the top of the pole. The stud is slidable along the accepting hole and against the step. The top of the pole is located the outside of the stripping plate while the bottom extends outward to form at least one block. The connecting head has a gap for encircling the pole and is slidable along the pole and against the block of the pole.

Abstract: The urisheath provided here includes an element of thin material (a strip) that allows at least two lengths of it to run in a parallel fashion down either side of the sheath. The is obtained by injection moulding the strip in liquid silicone in the silicone injection moulding process for the urisheath, either by one, two or more component injection moulding. The injection moulding takes place in an injection moulding form for a urisheath with a cavity for the body portion and a cavity for the strip portion wherein the cavity for the body portion is connected to the cavity for the strip portion creating an attachment zone between the strip and the sheath.

Abstract: A composite spout which does not permit a sleeve fitted onto the core to be deviated during the injection forming and does not permit end surfaces of the sleeve to be exposed in the spout body. A spout body is injection-formed in a state where a sleeve having a functional resin layer disposed as an intermediate layer is fitted as a core onto the core member of an injection-forming metal mold such that the inner peripheral surface only of the sleeve is substantially exposed on the inner peripheral surface of the spout body. A tilted surface is formed on the inner peripheral surface at one end of the spout body in at least a portion thereof in the circumferential direction, the tilted surface being tilted outward in the radial direction from a position in agreement with the inner peripheral edge at the one end of the sleeve or from the inside thereof in the radial direction facing the one end of the spout body.

Abstract: A ventilation device (10) for a motor vehicle includes a housing (12) made of plastics and at least one ventilation flap (14) molded to the housing (12). The housing (12) has an opening (24) in the connecting region of each ventilation flap (14). A mold for producing the ventilation device (10) includes two cores (26, 28), which in an injection position define the contour of a ventilation flap (14) and in a demolding position provide for demolding the molded part formed in the mold. In the injection position, an opening (32) is formed between the two cores (26, 28) in the connecting region of the ventilation flap (14). In a method for producing the ventilation device (10) by means of the mold, the ventilation flap (14) is molded to the housing (12) through the opening (24) in the housing (12).

Abstract: In a method of manufacturing an electronic device, an electronic element is disposed on a wiring plate that is electrically coupled with a connector terminal, a first surface of the wiring plate is covered with a first casing element and a second surface of the wiring plate is covered with a second casing element to form an electronic circuit part, the electronic circuit part is disposed in a case cavity of a molding tool, and a resin is filled into the case cavity to form the resin-molded case while keeping a state where a first pressure that pushes the first casing element toward the wiring plate and that changes with time is substantially equal to a second pressure that pushes the second casing element toward the wiring plate and that changes with time.

Abstract: A composite material component for an injection molding assembly includes a first portion formed of a precipitation hardened, high thermal conductivity material and a second portion formed of a precipitation hardened, high strength material, which are integrally joined together. The thermal conductivity of the high thermal conductivity material is greater than the thermal conductivity of the high strength material, and at least one strength aspect of the high strength material has a value greater than the corresponding value of the same strength aspect of the high thermal conductivity material. The high thermal conductivity material and the high strength material can be precipitation hardened together under the same precipitation hardening conditions to achieve increases in the value of at least one strength aspect of the high thermal conductivity material and the value of at least one strength aspect of the high strength material, relative to their respective unhardened conditions.

Abstract: A method of making an injection moulded container for housing information storage media, e.g. a DVD, the container having a base portion (10) and a lid portion (11) moveable about a spine portion (12) between open and closed configurations and holding means (15) for holding the media within the container, the method involving the use of an injection moulding tool comprising two carrier units (40, 41) each adapted to receive a plurality of inserts therein which define a cavity for forming the container: a first set of the inserts (50-59) for forming a first set of features of the container being formed of a first material, e.g. steel, and a second set of. inserts (42-45) for forming a second set of features of the container being formed of a second material, e.

Abstract: A cover (200) for portable electronic device includes a foil film (30) and a housing (40). The foil film includes a transparent view panel (31) and a keypad (33) integrally formed thereon. The housing is integrally formed with the foil film. The housing has a view panel opening (41) and a keypad opening (43) defined therein. The view panel opening and the keypad opening respectively correspond to the view panel and the keypad of the foil film. A method for making the cover includes the following steps: forming a foil film by injection molding, the foil film having a transparent view panel and a keypad; and integrally forming a housing on an inner surface of the foil film by injection molding, the housing having a view panel opening and a keypad opening respectively corresponding to the view panel and the keypad of the foil film.

Abstract: A probe for use with a pulse oximeter apparatus is disclosed, as are a fixture for and a method of making the probe. The probe includes a housing and two fiber optic bundles. The first bundle has an emitter portion at one end, and is used for conducting light from a source thereof to the emitter portion from which the light is transmitted for transillumination through a body part. The second bundle is for conducting the transilluminated light incident upon a detector portion thereof to the pulse oximeter apparatus. The housing is overmolded onto the bundles so that the emitter and detector portions are securely positioned diametrically opposite each other across an opening defined by the housing. The overmolding makes the alignment of the emitter and detector portions largely impervious to movement of the body part when placed within the opening and thus between the emitter and detector portions.

Abstract: An injection molding device configured for manufacturing a foil decorated molding, includes a channel defined in the mold, and a thermal medium source connected to the channel of the mold for inputting thermal medium into the mold via the channel to press the foil.

Abstract: A plastic closure for sealing a container, the closure having a top portion and a skirt portion depending from the top portion. The closure has an annular sealing rib which extends within the cavity defined by the top portion and the skirt portion. The rib includes a first portion having a substantially cylindrical inner surface extending away from the underside of the top portion and disposed radially inward of the skirt and a second, frusto-conical, portion contiguous with the end of the first portion distal to the underside of the top portion and extending radially inwardly and terminating in a circular free edge, such that during engagement of the cap with the neck of the container, the second, frusto-conical, portion will be engaged by the free end of the neck and folded back against the first portion of the rib to form a gas-tight seal between the neck of the container and the closure.

Abstract: An injection molding machine has a motor (31) provided with a brake unit (34). The brake unit (34) generates a braking torque greater than or equal to a maximum torque that the motor (31) is capable of generating. Thereby, the rotation of an output shaft (32) of the motor (31) is stopped. Therefore, at the time of stopping driving of a drive part and performing a predetermined operation, it is possible to stop a driven part from moving suddenly.

Abstract: Disclosed is a preferred mold design for producing plastic, injection molded preforms, which may be blow-molded into a container of a final, desired shape. A preferred mold includes a combination of hardened material components and high heat transfer material components to provide a mold having good wear characteristics, for a sufficiently long useful life, and to enable rapid cooling of the injected preform, in order to reduce the cycle time of an injection and cooling cycle. In some arrangements, the hardened materials may form a portion of the preform cavity thereby slowing the rate of cooling in those areas and inducing a semi-crystalline or crystalline structure in the cooled preform.

Abstract: A nozzle assembly for an injection molding assembly has a nozzle housing having a melt channel extending therethrough, a nozzle tip, and a retainer that retains the nozzle tip against the nozzle housing. The nozzle tip is formed of a precipitation hardened, high thermal conductivity material and a precipitation hardened, high strength material, which are integrally joined together to form the body. The thermal conductivity of the high thermal conductivity material is greater than the thermal conductivity of the high strength material, and the strength of the high strength material is greater than the strength of the high thermal conductivity material. The high thermal conductivity material and the high strength material can be precipitation hardened together under the same precipitation hardening conditions to achieve increases in the value of at least one strength aspect of the high thermal conductivity material and the value of at least one strength aspect of the high strength material.

Abstract: A waterproof slide fastener and a manufacturing apparatus thereof are disclosed, wherein each fastener element has a coupling head, a neck portion, a body portion, and leg portions which are continuously fused and integrated, a terminal end is projected from a gap between upper/lower half portions of the coupling head, upper/lower flanges of a slider make a sliding contact with a surface of each of upper/lower half portions of each leg portion, each half portion of the leg portion extending from the body portion via a crotch portion and guiding the flanges, two or more leg portions are disposed with a predetermined interval in a sliding direction, an entire shoulder width of a shoulder portion is larger than a body width of the body portion if it is provided, thereby intensifying fixing strength between a fastener tape and fastener elements and waterproofness, and allowing a smooth sliding of a slider.

Abstract: An anti-drool mechanism suitable for use in an injection molding system is provided herein. An injection molding machine includes a retractable machine nozzle for injecting a melt stream into a manifold. Between the machine nozzle and the manifold is an anti-drool mechanism, which includes a melt passage and a fixed pin disposed within the melt passage. The fixed pin is sized so that the melt stream will flow around the pin. The fixed pin has a head portion configured to engage with the machine nozzle and includes a first sealing surface. An actuated shut-off collar is also disposed within the melt passage, surrounding the pin, and includes a second sealing surface configured to cut off the flow of the melt stream when in contact with the first sealing surface.

Abstract: Disclosed is a drive unit, in particular for an injection unit or an ejector of an injection molding machine, comprising a stroke spindle device with a spindle and a spindle nut, and a prestressing device for prestressing the spindle that is dischargeable in a displacement phase of the stroke spindle device and is chargeable when the spindle is driven in the opposite direction, wherein the stroke spindle device and the prestressing device are supported by the same component, and wherein a load measuring device is provided for measuring the load acting on the spindle, which absorbs the forces acting on the component.

Abstract: An injection molded resin gear 1, which is molded by injecting a resin material from a plurality of pinpoint gates 13 into a cavity 2 of a die, includes a rim 7 having teeth 8 on its outer periphery, a shaft supporting portion 5 into which a shaft 3 is to be fitted, a web 6 extending in radial directions to connect the rim 7 to the shaft supporting portion 5, and a plurality of resin flow velocity regulating grooves 11.

Abstract: Disclosed is a method of a mold-spraying apparatus for use with a molding apparatus. The mold-spraying apparatus has: (i) a spray nozzle, (ii) a rotatable shaft being supportive of the spray nozzle, and (ii) a camming surface. The method includes: (a) engaging the rotatable shaft with the camming surface, and (b) moving the camming surface so that the rotatable shaft may rotate.

Abstract: The present invention provides a component molding method for increasing the strength of a resin component, such as a lens holder, used in manufacturing a lens drive unit, and also provides a resin component, and a component molding die. An initial flow direction of a resin injected from a gate 9G, from which a resin is injected into a cavity C, is set to extend substantially along a direction in which stiffness and strength of the resin component is needed to be higher than that in any other direction, by hitting the resin injected from the gate 9G against an inclined inner wall surface 33a of an inner wall of the cavity C to thereby change the flow direction almost 90° .

Abstract: An internal core is separated along a horizontal plane delineated at the transition point between the tapered wall portion and the parallel wall portion of the core to divide the core into a tapered wall component part manufactured by a WEDM process to obtain the desired shape and configuration and a parallel wall component part manufactured by a right angle milling or WEDM with a right angle manufacturing process to obtain the desired shape and configuration. The tapered and parallel wall component parts are joined together to form the desired internal core.

Abstract: A semiconductor device includes a plastic housing and a semiconductor chip, wherein the semiconductor chip includes an active top side and a rear side. An interposer is arranged on the active top side of the semiconductor chip. At least a portion of the interposer is embedded into the plastic housing, while the top side of the interposer forms the top side of the semiconductor device. A top side fitting shape is arranged on the top side of the interposer, where the top side fitting shape has a predetermined radius of curvature that is free of plastic housing composition, and the top side fitting shape has a convex or concave lens-shaped sphere segment shape.

Abstract: Mold (20), provided with a mold cavity which is at least partly defined by a movable wall part (50), wherein injection means (34) are provided for introducing material into the mold cavity, which injection means comprise at least one injection opening (34A) which is provided in at least one stationary wall part (80) of the mold cavity, wherein said stationary wall part (80) is at least partly surrounded by said at least one movable wall part (50).

Abstract: A hollow coated molded product is easily produced whose interior is coated, by using first and second moldings injection-molded through a first injecting step. Against first and second moldings injection-molded through a first injecting step, a coating device provided on a robot hand is butted and forms coatings thereon at a step at which a movable mold is separated from the fixed mold and thereafter, the first and second moldings are butted against each other and integrated through a second injecting step, whereby a coated molded product is formed.

Abstract: Disclosed is: (i) a mold-spraying apparatus of a molding system and/or (ii) a molding system having a mold-spraying apparatus, and/or (iii) a method of a mold spraying apparatus of a molding system, and/or (vi) a method of a molding system having a mold-spraying apparatus, amongst other things.

Abstract: The product and method of manufacture of cold water-soluble and biodegradable ammunition for the improved environmental impact and safety of ammunition.

Abstract: An apparatus and method for a hot runner injection molding system. The injection molding system has a plurality of melt conveying components defining a melt path from a melt source to a mold cavity and a mold housing. A force sensor or load cell is utilized between at least one melt conveying component of the system and the mold housing to measure a force generated due to thermal expansion of the melt conveying component during start-up and/or operation of the system and to provide an output to a receiving device. In an embodiment, once a sealing load or a predetermined preload force has been reached, an injection molding cycle may begin.

Abstract: A retaining device for an injection mold is disclosed. The retaining device has a device body which has a top surface and a bottom surface. A live bearing is mounted in the device body such that a portion of the live bearing extends above a top surface of the device body. The device is secured such that the live bearing supports movement of a first portion of the injection mold. A shoulder surface is formed where a body head portion interfaces with a body base portion. A spring is disposed is around the body base portion such that a spring top is in communication with the shoulder surface, and a spring bottom extends below the bottom surface of the device body. The spring creates a “pre-load” force that will hold the slide in place. Optional washers can be added to the device to adjust the “pre-load.

Abstract: A movable mold and a slide mold are employed. There is also employed a deposition apparatus which is equipped with a deposition element such as a target electrode in the inside of a depositing chamber. A body portion and a cover member are primarily molded by the movable mold and the slide mold. The molds are opened while the body portion being left in the movable mold and while cover member being left in slide mold. The body portion left in the movable mold is deposited in the molds with its inner surface being covered with the depositing chamber. Next, the slide mold is driven so that the cover member may be registered with the deposited body portion. Then, a secondary molding resin is injected to integrate the body portion and the cover member.

Abstract: The method employs a stationary mold having depositing recesses equipped in its inside with a deposition element such as a target electrode, and movable molds made slidable. A primary molding is performed to form a body portion and a cover member to have joint portions around their opening. The body portion left in the vertically sliding mold is deposited after it was densely covered with the depositing recesses. Next, the deposited body portion and the cover member, as left in the molds, are registered and mold clamped, and the molten metal is injected to integrated the joint portions.

Abstract: A drive unit, in particular for a closing unit, an injection unit, or an ejector of an injection molding machine, may be used where a high axial force is applied through a hydraulic power converter. A cylinder of the power converter may be fixed relative to a frame of the injection molding machine through the intermediary of a holding device which is functionally separate from guidance of the cylinder on the frame of the injection molding machine.

Abstract: A mold for an injection molding apparatus includes a light-transmitting part forming at least a portion of the mold, and configured to transmit light to a cavity to be filled with photo-setting resin.

Abstract: An injection molding apparatus 80 has a cavity 64 and core 65 co-operatively defining a void of inverted J-shape transverse cross-section for molding a garment hanger 10. A first leg 115, 127 of the J-shape cross-section forms a front of the garment hanger, a base 111 of the J-shape cross-section forms a transversely arcuate upper face of the garment hanger for receiving shoulders of a garment to be suspended from the garment hanger and a second leg 116, 126, opposed to the first leg, and substantially shorter than the first leg, forms a return rear portion of the garment hanger. A garment hanger molded in the injection molding apparatus is also disclosed.

Abstract: A member for a resin molding machine wherein it has a face contacting with a molten resin, and at least a part of the face is covered with a film of an oxide of a base material of the face or a component contained in the base material. The use of the member in the molding of a resin allows the prevention of the incorporation of a contaminant associated with the deterioration of a melt of the resin into a molded article from the resin.

Abstract: Disclosed herein is an injection mold for glass encapsulation, which has a variable support unit connected to a pressure control unit so as to support a glass panel with a constant force. The injection mold for glass encapsulation is constructed to put a glass panel between upper and lower molds and integrally form a mold along an edge of the glass panel. The injection mold includes a support unit supporting a lower portion of the glass panel and moving up and down along a support recess which is defined in the lower mold, a shock absorbing unit having a cylinder to press and support the support unit using elastic force, and a pressure control unit maintaining hydraulic pressure in the cylinder at a preset pressure.

Abstract: Contact lens molds and systems and methods for producing contact lens molds are described. The contact lens mold sections include two optical quality surfaces, a flange circumscribing at least a portion of the two optical quality surfaces, and an elongate member extending from the flange. Two mold sections can contact one another to form a mold assembly having a contact lens shaped cavity. The mold sections are structured to form a contact lens having an edge that does not require further physical modification before placement on an eye. Systems and methods are described which direct a molten polymeric material into cavities corresponding to the mold sections.

Abstract: A die for molding a disk substrate capable of forming fine recessed and projected pits and grooves up to the outer periphery of the disk substrate by preventing low heat conductive elements from peeling off and burrs from occurring on the outer periphery thereof. The die includes a first base die, a second base die disposed oppositely to the first base die, a first low heat conductive element fixed to the first base die, a stamper fixed onto the first low heat conductive element, a second low heat conductive element fixed onto the second base die, and a ring-like regulating member fitted to and in slidable contact with either of the first and second low heat conductive elements. The die is characterized in that the end part of the ring-shaped regulating member is positioned within the range of the outer peripheral side face of the low heat conductive element in slidable contact therewith.

Abstract: A display apparatus is provided. The display apparatus includes a stand body arranging cables connected to a main body and reducing costs and time in manufacturing the display apparatus. The display apparatus includes a stand base, the stand body, the main body, and a cable holder. The stand body is supported by the stand base. The main body displaying images is supported by the stand body. The cable holder collecting cables is connected to the main body, the cable holder being attachable to a mounting portion of the stand body and detachable from the mounting portion of the stand body.

Abstract: Method and apparatus for molding and assembling a composite part assemblies in, for example, a plastic injection-molding machine. Complementary mold portions associated with a mold plate and rotatable turret form plural parts. Assembly apparatus associated with the turret assembles the plural parts into an assembly. A further turret may be provided to add a complementary part to the assembly to make a final assembly. The method includes manufacture of composite part assemblies and final assemblies.

Abstract: A mold structure of a spike comprises a male mold base and a female mold base, and the female mold base is corresponded to the male mold base. The female mold base comprises a first female mold, a second female mold, a third female mold and a thimble. The first female mold is fixed on the female mold base, and the first female mold is formed a through hole therein; the second female mold is penetrated into the through hole of the first female mold, and the second female mold is formed a through hole therein; the third female mold is penetrated into the through hole of the second female mold, and the third female mold is formed a through hole therein. And the thimble is disposed on a thimble base, and correspondingly penetrated into the through hole of the third female mold.

Abstract: A vacuum forming apparatus for forming a tire, wheel, or other item in a mold having a cavity with the shape of the item to be cast that is contained in the apparatus. The vacuum forming apparatus utilizes a bell shaped outer cover arranged to seal along its lower edge to a mold base plate, and includes a canister maintained under a deep vacuum and arranged in or connected to the apparatus as a reservoir to receive a mixture of urethane constituents, with the deep vacuum removing air from that mixture, and the air free mixture is passed through a valve and into the mold cavity. A low level vacuum is pulled through a vent valve in the bell shaped outer cover to pull the flow of urethane material through the cavity, filling the mold. With the cavity filled, the canister valve is shut and the vent valve in the bell shaped outer cover is closed, allowing the urethane material in the mold cavity to cure, and the mold is broken open and the cast item is removed from the cavity.

Abstract: A magazine for screws includes seats defined by walls connecting longitudinally an insert end with an exit end of the seats, wherein in at least one seat a screw having a shank connecting a screw-head directed towards the insert end to a screw-tip directed towards the exit end, the screw-head having a first radius and the shank a second radius smaller, is housed, than the first radius, the at least one seat being formed internally with at least one wing-member running longitudinally from near the insert end towards the exit end, the at least one wing extending from a wing-root connected to the seat wall to a wing-tip projecting into the seat. In any arbitrary plane intersecting the wing and seat transversally to the longitudinal, the extension of the at least one wing from wing-root to wing-tip radially overlaps the radius of the screw-head, and the at least one wing is flexible from the wing-root towards the wing-tip.