Abstract: Break-away closures are formed by an injection molding process with a closure part in interference path with a forming core for interference in use with a counterpart surface of a container neck. The process and apparatus disclosed permits stripping of the formed closure from the core by selectively creating free encircling space about the interference closure part for expansion thereof during stripping. The closure has detent surface molded therein which assists the stripping operation and the process and apparatus provide for the application of stripping forces at spaced locations simultaneously to permit stripping of the closure in part without axial loading thereof.

Abstract: A method for controlling back pressure in an electrically-operated injection apparatus wherein rotation and forward movement of an injection plunger within an injection heating tube are carried out by a first electric motor which provides a driving force, wherein backward motion of the injection plunger during the charging of material presses against a screw threaded rotatable part and is thereby converted into rotational motion of the threaded rotatable part, and wherein the rotational motion is controlled to control back pressure of the injection plunger. A second electric motor is used for controlling the back pressure on the injection plunger by controlling rotation of the threaded rotatable part. The backward force exerted on the injection plunger or the direct pressure of the molten material within the injection heating tube are electrically measured. By driving and controlling the second motor through feedback control, the back pressure is made to coincide with a set, preselected back pressure value.

Abstract: Method for adjusting the compression stroke allowance of a vertical injection-compression molding machine including a slide plate mounting thereon a mold clamp cylinder and an upper mold in opposition to a lower mold on a machine bed, and a lift cylinder for moving the slide plate up and down along tie bars, the method including the steps of: downwardly extending a piston rod of a hydraulic cylinder connected to the slide plate to a stroke end: upwardly extending a piston rod of an air cylinder connected to the bed thereof, with the upper and lower molds in contact with each other, until a micrometer at the upper end of the air cylinder piston rod abutts the lower end of the hydraulic cylinder piston rod; fixing the air cylinder piston rod in this state; upwardly retracting the hydraulic cylinder piston rod; setting the micrometer at a desired compression stroke allowance; lowering the hydraulic cylinder piston rod to the stroke end thereof; and lifting the slide plate so as to allow for injection-compression

Abstract: Method and apparatus for uniformly macroscopically expanding and, if desired, aperturing a plastic web. This is preferably accomplished by supporting the plastic web on a moving three-dimensional forming structure which is supported in a fluid pressure differential zone by a stationary support member. By providing a relationship between the size and pattern of the apertures in the stationary support member and the size and pattern of the apertures in the three-dimensional forming structure, substantially all of the apertures present in the forming structure are unobstructed by the stationary support member at some point during the forming structure's traverse of the fluid pressure differential zone. Thus the resultant plastic web is uniformly debossed and, if desired, apertured in the pattern of the three-dimensional forming structure.

Abstract: The plastic molded article is produced by heating a mold by contact with a preheated salt bath. The salt bath is readily maintained at a uniform temperature and is self-insulating for energy efficiency. A noncontact infrared sensor monitors the mold cavity temperature while in the salt bath, and the mold is removed from the bath when the proper mold temperature is reached. A charge of plastic powder is introduced into the mold by clamping the mold to a powder slush box with the mold cavity confronting the opening of the box. The mold and box are then simultaneously rotated to pour the plastic charge into the mold. The plastic charge forms a skin on the cavity surface and additional plastic material may be built up to provide additional thickness. The mold and box are then separated; the mold is then postcured and cooled, whereupon the finished article may be removed from the mold.

Abstract: A method for controlling the opening/closing of a mold in an injection molding machine providing an increased accuracy. A changeover position indicative of a speed of a movable plate or the changeover position of a pressure is preset in accordance with a corresponding position of the movable plate. The value thus set is arithmetically converted to a corresponding displacement distance of a rod of a mold-clamping cylinder. The converted value is compared with the detected displacement of the rod, and when the two values coincide, the hydraulic pressure controlling the mold is changed appropriately.

Abstract: A method of molding a sleeve on a corrugated pipe consisting of an inner wall and fusion-bond ridges. Two clamps can close to engage several of the ridges. One to three of the ridges project into a molding space between the clamps. A core is inserted into pipe and closes the molding space. Hot pressurized resin softens and collapses the projected ridges and fusion bonds the pipe to the sleeve portion of the molding space.

Abstract: A method of operating a vacuum-forming machine and the machine which operates by this method, in which once the mold halves are closed on the foil webs for vacuum drawing and fusion of the vacuum drawn container halves come together to produce a hollow article, the mold halves move at the velocity of the web to a lower position spaced from the upper position by a distance sufficient to permit cooling of the molded articles. A spring or other force-storing element is stressed during this movement so that when the mold opens at the lower position, it is driven upwardly at a substantially higher velocity to return to the starting position.

Abstract: Apparatus for reducing the waste neck area in a mold of vinyl cast articles such as automotive arm rests, head rests and parts of similar construction includes a powder box of gellable material having a supply spout with its exposed outer surface area covered by a liner of heat insulating material; a waste inlet neck on a heated, machined nickel mold is sealed by the liner when the powder box is joined to the mold. The powder box spout is at room temperature and shields the inlet neck to prevent gel build-up on the inlet neck to effect considerable cost by both a reduction in waste deposits of gel and a reduction in labor required to trim a waste area on the mold. To obtain the coating, the mold is coated with powdered vinyl (hereinafter gellable material) by casting from the powder box to the mold and the excess material is removed from the mold by dumping it from the mold into the powder box.

Abstract: In a method for forming articles by injection molding, in which a melted plastic material is injected into a cavity formed between a movable die and a stationary die, the method including the steps of injecting the melted plastic material into the cavity under the condition of substantially no pressure, and pressing the movable die against the stationary die during or after injection so as to press-mold the article.

Abstract: A method of controlling the heating of hot runner molds for injection molding of thermoplastic objects is disclosed, whereby the mold cavities (11, 12) receive the material to be molded via channels or runners divided into five heating zones (I through V), the temperature of each zone being controlled by means of an electric heating element (EC) associated with a thermocouple. In the event of failure of one zone's thermocouple, heat control is continued in said zone according to the power applied to the heating element of an adjacent zone.

Abstract: An improved vacuum forming process for forming a deep drawn plastic article with a flange in an area of high forming stresses wherein a mold mounted on a base forms the shape of the article. A sheet of hot plastic material is placed over the mold and a vacuum is drawn to form the plastic sheet into the shape of the mold to form the article. The improvement is forming a character in the mold portion that forms the flange in the area of the high forming stress, said character having dimensions such that properly heated plastic sheet material will be imprinted with a predetermined clarity during the molding operation. A heated sheet of plastic material is placed over the mold and a vacuum is drawn to draw the plastic material around the mold including the mold portion that forms the flange in an area of high forming stresses. The plastic material is then solidified and removed from the mold. The flange is visually inspected to determine if the imprinted character has the predetermined clarity.