Abstract: PTFE vascular tubing is guided on to a tapered ultrasonic horn as the horn is oscillating at a high frequency. This action causes the end of the tubing moved onto the horn to expand. The expanded tubing is then positioned on a mandrel having a desired shape, such as tapered, and resintered. The finished tubing with an expanded diameter on one end and a non-expanded diameter on the other end is then removed from the mandrel, and is ready for use. Untapered tubing can also be radially expanded by this method to provide a thinner wall.

Abstract: A method of producing mouldings from paper and a thermoplastics. Paper and thermoplastics waste are reduced to shavings or chips. The same are introduced into a screw extruder to melt the thermoplastics and prepared therein to be extrudable. The mixture of melted thermoplastics and paper shavings is shaped continuously into the moulding by means of an extruding tool disposed after the screw extruder. The method is used more particularly with waste of plastics-coated packing paper as feed material.

Abstract: A high barrier container includes a barrel-shaped container body having a sealed end and an open end, and a closure member. The closure member includes a circular laminated central closure panel and a peripheral flange. The laminated central closure panel includes a top plastic layer and gas-impermeable layer bonded thereto. The closure member is spin welded to the container body such that a spin-weld interface is formed between the open-end part of the container body and the flange.

Abstract: A process for making compacted particulate polyolefin compositions is described. The process includes the steps of:(a) thoroughly mixing a molten blend of a polyolefin and a modifying agent;(b) cooling the blend to a temperature below the melting temperature of the polyolefin, while masticating the blend; and(c) continuing to masticate the blend and subsequently extruding the blend below its melting temperature to produce strands or pellets in crumble form.The modifying agent may be solid or liquid at S.T.P. and should be mobile at processing temperatures. Examples of modifying agents include polyalkylene glycols, polyisobutylene. A preferred polyolefin is polyethylene. It is preferable that the process take place in a twin-screw extruder.

Abstract: In a method and a device for making shaped objects from plastic refuse plasticized in a roller extruder under pressure and ejected from the nozzle of the extruder a plurality of molds are provided transported to the extruder, filled thereby and transported therefrom. Each mold has at the end face a plate having a filling opening. During the filling process this plate sealingly overlaps the surface surrounding the nozzle so that the mold can be filled with plasticized plastic under the pressure generated in the roller extruder.

Abstract: Method of welding two hollow ceramic half-components containing an organic binder whereby each half-component is first loaded into a die, the jointing planes of the two half-components are then brought into contact by bringing together the two dies, working pressure is thereafter applied to one of the half-components in a direction perpendicular to the jointing planes and vibration is simultaneously applied to the other half-component in a direction parallel to the jointing planes to effect the welding of the two half-components by interpenetration. The two dies are then separated and the joined monobloc component is removed and sintered without altering the component's monolithic quality.

Abstract: Extrusion machine and process, the machine having a barrel having a feed section for receiving solid extrusion material, and containing a screw for moving the solid extrusion material through a solids conveying section to a compression section of the barrel to generate heat and pressure to melt the extrusion material and force the melt through a downstream extrusion die. The solids conveying section of the barrel has a cross-section comprising a plurality of flat or slightly curved surfaces which extend substantially tangentially relative to the extrusion screw circumference, providing axial recesses which restrain the rotation of the solid extrusion material with the screw as it is moved axially into the compression section. The present machine and process causes plastic extrusion composition to be packed as a non-rotating mass to fill the solids-conveying and compression sections and increase the dead head pressure and extrusion output of the machine.

Abstract: A friction welded part having a sealed flash trap is disclosed, along with a method for producing such parts. The friction welded parts have a hollow cylindrical part and a second part to which the hollow cylindrical part is friction welded. There is an internal flash trap in the region of the weld, and the hollow cylindrical part is pinched inwardly or a conical flange on the flash trap is deformed outwardly so as to seal the flash collecting portions of the flash trap from the hollow portion of the hollow cylindrical part remote from the weld. The method involves the conventioanl steps of rotating the parts with respect to each other under pressure, stopping the rotation, and exerting high pressure to form the weld. In accordance with the invention, the hollow cylindrical part in the region adjacent the flash trap is then forced inwardly or a flange of the flash trap is forced outwardly so as to effect the seal.

Abstract: Extrusion process and apparatus, the apparatus including an extrusion barrel having axial grooves which extend through the feed section and solids conveying section and disappear at the exit end of the compression section. The apparatus also includes a helical thread extrusion screw having a maximum channel depth in the feed section, which depth disappears at the exit end thereof. The process and apparatus causes plastic extrusion composition to be packed as a non-rotating mass to fill the solids-conveying and compression sections and increase the dead head pressure and extrusion output of the apparatus.

Abstract: The invention relates to a process for degassing and pelletizing polyolefin particles produced by a gas phase polymerization. The polyolefin particles are submitted to a primary degassing, preferably at the outlet of a reactor for catalytic polymerization in the gas phase. Then the polyolefin particles are subjected to a secondary degassing step comprising agitating the particles by a mechanical stirrer and converting the mechanical energy therefrom into heat such that the temperature of the particles is brought to between 80.degree. and 120.degree. C. which is close to minimum sintering temperature Ts so that the polyolefin particles are substantially freed from the gases accompanying them. The heated degassed polyolefin particles are then pelletized in an extruder of a pelleting unit.

Abstract: A screw extruder and a method of operation thereof. The screw extruder comprises a barrel including a section that is supported for rotation about the longitudinal axis of the barrel. A screw extends and is supported for rotation in the barrel; and, in use, rotation of the screw rotates and advances plastic material through the barrel. Rotation of the screw also causes the rotatable barrel section to rotate, and a brake is connected to that rotatable section to maintain the rotational speed of the rotatable section less than the rotational speed of the extruder screw. The rotational speed of the screw relative to the rotatable barrel section controls the relative rates at which plastic is mixed, heated, and pressurized in the barrel.

Abstract: A plumbing construction is provided including a pipe, a fitting, and a bushing, each formed from polybutylene and providing a fluid-tight connection between the pipe and the fitting. The bushing is mounted about the pipe and an end of the pipe and the bushing is inserted into the fitting. The bushing is rotated with respect to the fitting to produce friction welds between the bushing and both the pipe and the bushing.

Abstract: An end component 3 is spin-welded into the cut end of an extruded tube 1 with the application of axial pressure but without the application of radial pressure to the weld area. The radial forces required to create a weld are provided by hoop stresses which are formed in the tube by shock-cooling the tube as it emerges from the extrusion die. When the tube is cut, the hoop stresses cause the cut end of the tube to contract radially prior to insertion of the end component. To assist in insertion of the end component, a cylindrical skirt thereof 4 is provided with a chamfered end 9.

Abstract: During spin-welding of an end ring to a container body, the weld area is subjected to a radial pressure by means of a wire cable tourniquet under the action of a pneumatic cylinder. The interference fit between the ring and body is measured by reference to the torque required for their slow speed relative rotation or to the axial force required for their assembly and, according to the measured interference fit, the radial pressure applied by the tourniquet during welding is controlled.

Abstract: An article of manufacture comprises a molded-plastic fitment such as one of the halves of a snap fastener molded in situ to a porous substrate such as a garment fabric. Various embodiments are described for the article, as well as dies for forming the same, and methods and a machine for making the same.

Abstract: A method and device for assembling connection fittings such as couplings, between hard components, such as metal pipe and a body formed of a softer substance to obtain a permanent coupling able to withstand aging and thermal shock conditions. The parts coupled are formed of materials of different hardness which are first force fit together. One of the parts is then rotated at high speed so that the part made of the softer material is locally heated until it melts. The result is a snug but swivelable connection free of internal stress.

Abstract: In order to stress relieve exposed portions of plastic welds, and thereby reduce susceptability of such welds to solvent-induced crazing and cracking, the welded parts are formed with flanges extending outwardly therefrom. These flanges are at least partially joined during welding, their adjoining surfaces providing at least a portion of the welded joint. After welding, the flanges are compressed in a direction transverse to their adjoining welded surfaces, the compression being of sufficient magnitude to exceed the yield strength of the flanges, thereby relieving stresses in the exposed portion of the welds. The flanges may be sheared, as by a blade which provides both transverse compressive forces and compressive forces in the direction of the adjoining welded surfaces. The flanges may be sheared through, so as to enable the sheared off end to be removed, or the shearing may penetrate only through the weld zone, providing a notch, but leaving the flanges in place.

Abstract: A game ball for playing baseball or softball, and the method for making the ball. The ball is formed of a hollow plastic shell filled with an expanded plastic material, and a cover completes the ball. The weight of the ball is provided by the weight of the shell, the expanded plastic filling the shell, and the cover. The COR, sound, and feel off the bat are provided almost entirely by the plastic shell. The material of the shell is an ionomer or a polyolefin, and the preferred material is an ethylene acid copolymer, the material for the shell being selected to have a hardness in the range of Shore D 30 to 65. The expanded plastic filling the shell may be any self-initiating material. The method for forming the ball is to mold two hemispheres, place a liquid mix for forming the expanded plastic into the lower hemisphere, weld the upper hemisphere to the lower hemisphere, the upper hemisphere having a vent hole at the top, and let the shell rest while the material expands to fill the shell.

Abstract: Joints between thermoplastic parts are friction welded (e.g., as by vibration welding) or otherwise thermally welded in such a manner that a non-uniform temperature distribution results during welding which effectively blocks flash flow from the edge of the joint, and upon cooling, produces a joint that is at least partially stress relieved and is resistant to solvent-induced crazing and cracking. Joints may employ nonparallel adjoining surfaces and/or flexural lips, which bend slightly under pressure applied during welding so as to produce a non-uniform pressure distribution and nonparallel welding surface over at least a portion of the resulting weld near the outside edge. In addition, one or more axial grooves may be used to isolate the nonparallel or lipped area of the weld from the remainder of the weld area so as to increase the lip compliance and reduce the effective pressure of molten material acting on the lip during welding.

Abstract: To relieve stresses in a plastic weld which may weaken the weld and increase its susceptibility to solvent-induced crazing or cracking, forces are applied to the weld zone (the interface between welded parts) after it has cooled to solid condition, but preferably when it is at a higher temperature than the regions of the parts adjacent thereto, which forces are higher than the yield strength of the material at the weld zone and lower than the yield strength of the material in the regions of the parts adjacent to the weld zone. The forces thereby cause yielding or plastic deformation which effectively relieves certain thermally induced stresses in the weld. Tensile stresses in the weld are thereby relieved, to reduce susceptibility of the weld to solvent-induced crazing or cracking.

Abstract: There is provided a hydraulic motor-driven extruder having raw rubber stock fed from coiled continuous strips into the extrusion portion thereof. The extruder includes a screw shaft and housing having decreasing diameter as material is transported toward the discharging extremity thereof. Surrounding this screw extruder there is provided heating bands of controlled temperature to impart additional heat. On discharge from the extruder the prepared rubber is deposited within an expandable cavity for selecting the desired volume of prepared rubber material. Once measured the prepared rubber is lifted from the cavity for insertion into the molding press.

Abstract: A thermoplastic container bottom is inertially spin welded into the interior of a cylindrical container body of paperboard internally lined with a layer of thermoplastic material. A body supporting mandrel has an expansible body engaging portion which is inserted into the body and subsequently expanded to define a cylindrical surface of a diameter exactly equal to that of the specified internal diameter of the body. A seating member at the end of the body supporting mandrel establishes the depth to which the container bottom is inserted into the body and is provided with a low-friction projecting resilient member which contacts the rotating bottom.

Abstract: Fixation of a stud on a workpiece is accomplished by depositing hotmelt adhesive agent on a fitting base of the stud, fastening the stud to a rotary tool, rotating the stud with the fitting base pressed against the workpiece and, after the adhesive agent has been activated to a prescribed extent by the heat of friction, stopping the rotation of the stud and pressing the fitting base against the workpiece.

Abstract: A friction welding fastener system is disclosed for fusing a thermoplastic material fastener to a substrate by heat of friction induced through the application of rotative and axial forces applied to the fastener. A cavity is formed inwardly of the bottom surface of the thermoplastic base member and a heat activated adhesive material having a bonding affinity for both the base material and the substrate material is inserted into the cavity to form a layer having a thickness equal or greater than the thickness of the base member. The base member is rotated with sufficient rotative and axial forces to cause the heat activated adhesive layer to adhere to the substrate.

Abstract: Methods and apparatus for vulcanizing rubber and like material (10). Ultrasonic energy at about 10 to 100 kilohertz is applied to the material (10) at an energy intensity sufficient to generate heat to a temperature in the range of about 200 to 300 degrees Fahrenheit, while a static pressure is applied on the material (10) sufficient to prevent substantial cavitation and material degradation. The application of the ultrasonic energy and the pressure is maintained for at least about 10 minutes for each 1/8 inch in thickness of the material (10).

Abstract: A motion-transmitting remote control assembly of the type including a flexible motion-transmitting core element movably supported in a conduit (28) supported by a fitting (12). A helical groove (24 ) is formed in a bore (14) in the fitting (12) and a raised helical ridge (30) extends radially from the conduit (28) and fills the helical groove (24) to provide retention of the conduit (28) within the bore (14) of the fitting (12). An apparatus (10) and method for attaching the fitting (12) to the conduit (28) wherein the fitting (12) is rotatably supported by a mandrel (82) as the conduit (28) is clamped (42) and forced into the bore whereby frictional engagement with the bore (14) of specific configuration causes the material of the conduit (28) to soften and move radially outwardly (30) to fill the helical groove (24).

Abstract: Process and apparatus are disclosed for manufacturing foamed articles such as tubes used as pipe insulation, which tubes are of a high impermeability and flexibility and are formed of a polymer, such as polyethylene or polypropylene, containing up to about 25% of an elastomer.

Abstract: A tube and fitting assembly is disclosed which includes a plastic fitting with a hollow pin frictionally receiving an end portion of a plastic tube, and an integral collar surrounding the pin and tube end portion and with the tube end portion clamped between the pin and collar. A method of making a tube and fitting assembly is disclosed which includes spin-forming the collar of a fitting about an end portion of a plastic tube while the end portion is disposed on a hollow pin concentric with the collar.

Abstract: Methods are disclosed for the bonding together of two similarly shaped articles of dissimilar thermoplastic materials utilizing oscillatory motion between the two articles combined with an external heat source to generate sufficient heat to form an hermetic seal therebetween.

Abstract: In order to control the fusion of a polyvinyl chloride plastic material which is being moved along a screw of an extruder from a feed section (36) through a compression section (37) to a metering section (39) and crosshead (26), the melt pressure is measured in the compression section. The melt pressure, which is indicative of the fusion qualities of the plastic material, is used to control the temperature of the plastic material in the feed section to cause it to be substantially homogenous at the crosshead.

Abstract: Disclosed is a process for the production of a hollow article comprised of a biaxially oriented thermoplastic resinous material, comprising the steps of heating a sheet of thermoplastic material to a temperature above the orientation temperature of the thermoplastic material; clamping an area of the heated thermoplastic sheet between a first mold half and a second mold half, the first mold half containing a pre - form mold surface having a configuration predetermined to provide for uniform wall thickness of the hollow article to be formed, the surface being at a temperature which is not higher than the orientation temperature of the thermoplastic material, and the second mold half having a cavity which corresponds to the shape of the hollow article to be produced; forcing the heated thermoplastic sheet by pressure differential into the first mold half against the surface; maintaining the thermoplastic sheet in contact with the surface for a period of time sufficient to bring the thermoplastic sheet to its ori

Abstract: A method of, and apparatus for, forming thin-walled synthetic plastic containers and like articles wherein areas are stretched out of the plane of heated thermoplastic material a portion of the axial length of the containers or articles to be formed to form top and bottom preforms, each with an open and a closed end; each preform, while still in the webs, is further axially and radially stretched, at a temperature conducive to orientation of the molecular and crystalline structure of the material, to a greater length still less than the axial length of the container or article to be formed; the preforms are severed from the webs to provide open ended top and bottom sections; and the open ends of pairs of top and bottom preforms are assembled and welded together to form the containers or articles.

Abstract: Methods and apparatus are disclosed for the bonding together of two similarly shaped articles of similar thermoplastic material utilizing oscillatory motion between the two articles to generate frictional heat therein sufficient to form an hermetic seal therebetween.

Abstract: A device (26) for softening the insulation of a wire (21) having a pair of opposed rollers (28, 30) and means (22) for mounting the rollers. The rollers (28, 30) are mounted in such a manner as to be movable away from one another to enable an insulated wire (21), to be wire wrapped on a terminal, to be passed therebetween. The rollers (28, 30) are also movable towards each other for engaging and softening the wire insulation.

Abstract: An apparatus and a method are provided where two relatively rotatable plastic tubes in telescoping relation are welded together at their telescoping, contacting interface. In practicing the invention, soft and flexible thermoplastic tubes are fitted in telescoping relationship, one inside the lumen of the other. Gripping jaws compress and shape the outer tube uniformly which stiffens the inner and outer tubes and defines a contacting interface. Axially spaced from the interface, the inner tube is chucked with shaping jaws to impart a polygonal, cross-sectional shape to the inner tube. Frictional heat generated by rotating one tube relative to the other tube softens the interface allowing the tubes to weld together when rotation is stopped.

Abstract: An improvement is disclosed in a process for producing foamed articles of thermo-plastic or thermo-setting compounds. The improvement reduces the number of steps normally followed to make a foamed product and cuts down on the time.

Abstract: This invention relates to plastic sheet material, and in particular concerns the production of a plastics sheet material which has a wide range of uses, because of the properties thereof.

Abstract: A composite coupler carrier assembly for railroad cars comprising a lower metallic attachment plate shaped and arranged to be mounted on the car structure supporting the coupler shank, and an upper planar polymeric bearing body of ultra high molecular weight polyethylene that defines an upwardly facing planar bearing surface on which the coupler shank rides. The metallic attachment plate and the polymeric bearing body are fixed to each other by the practice of a spin welding technique involving the forming of a plurality of apertures of frusto-conical edging in the attachment plate, in which the small sides of the apertures are on the same side of the plate, and placing the underside of the polymeric bearing body against said side of the mounting plate, and spin welding in each aperture, to the bearing body, a polymeric disc that is of the same material as the bearing body, and that is proportioned to thereby anchor the attachment plate to the bearing body.

Abstract: Heat treatment of a material, e.g. a finely divided resin, wherein the material is introduced into a drum and agitated by rotating, spaced blades which whirl the material into a dispersion. The action of the blades heats the resin particles so that heat for the heat treatment is provided. The heat treatment can be, e.g. to cause small resin particles to coalesce with larger particles in the processing of polyethylene reactor flake, to improve flowability of the resin, or to admix resin and additive. To obtain increased capacity while the size of the apparatus is maintained within reasonable limits, two intersecting, generally cylindrical drums, each outfitted with an agitator, are used. Apparently the dispersions of the respective agitators slam into each other in the vicinity of the intersection causing additional heating.

Abstract: A process for producing articles of polytetrafluoroethylene (PTFE) is disclosed. The process allows some of the conventional plastic fabrication techniques to be used with PTFE which until now have not been possible. The process comprises the steps of intensively mixing and thermokinetically heating PTFE resin in an enclosed container with a plurality of blades attached to arms rotating about an axis, with a blade tip speed of at least 30 meters/second, to a predetermined discharge temperature of above 370.degree. C., discharging the resin at the discharge temperature, forming the resin into a desired shape at a temperature at or below the discharge temperature, holding the resin in the desired shape above a predetermined forming temperature for a predetermined time, and cooling the resin in the desired shape.

Abstract: Plastic sheet material used for forming box blanks are provided with soft, bendable score lines by applying frictional heat through rapid vibration. The sheet material is clamped under high pressure between a resilient make-ready and a scoring tool, and is subjected to the vibratory action which generates frictional heat sufficient to melt the plastic material at the engaged interface, thereby forming a score line along which the sheet material may be bent to form an assembled box. A completed box blank may be formed in a single operational step, by cutting the box, impressing the score lines, and impressing embossments, if required, simultaneously in a single operational cycle of seconds duration.

Abstract: A process is described for improving the rate of production, other conditions being equal, of extruded polymer products, containing foaming- and/or cross-linking agents, which particularly resides in using a "melting torpedo" rotatable element in the melting section of the extrusion apparatus.

Abstract: A thermoplastic container bottom is inertially spin welded into the interior of a cylindrical container body of paperboard internally lined with a layer of thermoplastic material. A body supporting mandrel has an expansible body engaging portion which is inserted into the body and subsequently expanded to define a cylindrical surface of a diameter exactly equal to that of the specified internal diameter of the body. A seating member at the end of the body supporting mandrel establishes the depth to which the container bottom is inserted into the body and is provided with a low-friction projecting resilient member which contacts the rotating bottom.

Abstract: A method of friction welding thermoplastic materials, such as a reinforcing plate to the inner surfaces of oppositely disposed legs of a generally U-shaped workpiece, wherein a flexible force applying means applies a force in a direction normal to the direction of relative motion between the parts but in the plane of the mating surfaces for urging the legs of the U-channel into intimate contact with the edges of the reinforcing plate. During a weld time interval the parts undergo relative linear reciprocating motion while being urged in intimate contact by the flexible force applying means which causes the mating surfaces to soften under the influence of friction. After the weld interval, the parts are returned to their original position and are held in forced contact for a time sufficient for the mating surfaces to solidify. Upon solidification the force ceases and the welded parts are removed from the apparatus.

Abstract: Apparatus located at the output end of a screw extruder comprising a mandrel to rotate with said screw and a jacket coaxial with the mandrel and rotatable in an opposite direction of rotation to the mandrel at a speed which is steplessly adjustable. Sealing lips co-operating with abrasion rings are preferably provided on relatively moving surfaces of the jacket and stationary housings and temperature adjustment means can be provided in the jacket and the mandrel.

Abstract: An injection molding apparatus is disclosed which includes a screw having a multichannel wave screw section. In the wave screw section, a helical passage defined by a radially extending helical screw flight is divided into a pair of flow channels by a radially extending helical barrier. The helical barrier is radially shorter than the helical conveying flight and the effective outer width thereof is axially narrower than the helical conveying flight. Each flow channel is provided with an undulating base surface that defines a plurality of wave cycles. The base surface varies in a radial direction between a valley portion and a crest portion for the wave cycle and a wave cycle is defined as extending between consecutive crest portions. The crest portions of one flow channel are helically displaced from the crest portions of the adjacent flow channel.

Abstract: A composite container is disclosed having a synthetic plastic end closure member spin-bonded to the thermoplastic synthetic plastic inner liner layer of a composite container body wall. The synthetic plastic end closure member includes annular downwardly depending inner fin and outer chime portions which are concentrically spaced to define therebetween an annular groove. One of the body and end members is rotated relative to the other member when they are in spaced vertical alignment, whereupon the members are axially displaced together to wedge the upper end of the body member into the annular groove of the end closure member. During this spin bonding process, the fin portion of the end closure member is supported against radial inward deflection, whereby the spinning frictional engagement between the fin portion of the end closure member and the inner liner layer of the body member causes softening and subsequent bonding of the fin portion to the inner liner layer.

Abstract: A friction welding apparatus for joining thermoplastic materials, such as a reinforcing plate to the inner surfaces of oppositely disposed legs of a generally U-shaped workpiece, includes flexible force applying means for applying a force in a direction normal to the direction of relative motion between the parts but in the plane of the mating surfaces for urging the legs of the U-channel into intimate contact with the edges of the reinforcing plate. During a weld time interval the parts undergo relative linear reciprocating motion while being urged in intimate contact by the flexible force applying means which causes the mating surfaces to soften under the influence of friction. After the weld interval, the parts are returned to their original position and are held in forced contact for a time sufficient for the mating surfaces to solidify. Upon solidification the force ceases and the welded parts are removed from the apparatus.

Abstract: The apparatus and method for making a resin caulker 10 begins with continuous extrusion of a resin cylinder 15. A multimandrel indexing machine 20 has a receiving station 22 positioned to align an empty mandrel 21 with extruded cylinder 15 so a leading end 18 of extruded cylinder 15 advances onto empty mandrel 21. A cut off device 19 cuts cylinder 15 at a predetermined length to form a resin caulker barrel 11 supported on mandrel 21. Indexing machine 20 then moves cut off barrel 11 to an assembly station 23 and brings another empty mandrel 21 to receiving station 22. An end closure 12 is joined to cut off barrel 11 at assembly station 23; and successive stations 24-29 of the indexing machine finish, print, and dry the assembled caulkers while supported on mandrels 21.

Abstract: A thermoplastic container bottom is inertially spin welded into the interior of a cylindrical container body of paperboard internally lined with a layer of thermoplastic material. A body supporting mandrel has an expansible body engaging portion which is inserted into the body and subsequently expanded to define a cylindrical surface of a diameter exactly equal to that of the specified internal diameter of the body. A seating member at the end of the body supporting mandrel establishes the depth to which the container bottom is inserted into the body and is provided with a low-friction projecting resilient member which contacts the rotating bottom.