A process for manufacturing hook-and-pile type fasteners is disclosed in WO 94/23 610 of the Minnesota Mining and Manufacturing Company. In this process, as also in the manufacturing process disclosed in U.S. Pat. No. 3,270,408, first pinshaped bodies are produced whose ends are reshaped into mushrooms in a second operating cycle. Mushroom heads with parts of the head flattened are disclosed in U.S. Pat. No. 3,196,490. The formation of a hook-and-pile fastener, for baby diapers or for hospital clothing in particular, is disclosed as a potential application for fastener elements produced in this manner.
A relatively large number of interlocking means per square centimeter are required in order for the hook-and-pile fastener elements to be used as fasteners for these types of clothing articles. This results in high costs for the shaping roller employed in the state of the art to shape the interlocking means. In manufacture of this shaping roller, it is necessary first to imprint at considerable expense a number of openings corresponding to the number of interlocking means. In addition, a vacuum device must be integrated to perform the function of orienting the stalks of the recesses. The shaping roller must be cooled to a specific temperature during operation. A second process step is required, in addition to production of the stalks, to form mushroom heads on the oriented stalks by contact with a heated roller.
Another disadvantage of the conventional process is due to the fact that the location of the extruder head containing the thermoplastic must be adjusted with very high precision. The extruder head must be opposite the shaping roller to obtain a flat backing of very slight thickness, as required, for example, for use in fasteners in baby diapers. For example, every repeated charging of the extruder head may result in maladjustment of the extruder head relative to the shaping roller, causing interruptions of production.
WO-A-94/29070 describes a shaping tool using a laser for the manufacture of plastic elements which can incorporate shaping of their surface. The shape is obtained by openings forming blind holes in a flat or circular cylindrical substrate. The shaping occurs as a result of the pressing of a pressure stamp on the shaping substrate. The shaped elements can be further modified in their shape by suitable subsequent processing steps following the shaping.
U.S. Pat. No. 3,399,425 describes a device for shaping of material surfaces, and among other things, for the shaping of interlocking means in the form of stalks projecting from a backing tapering conically, and on the end more distant from the backing being wrinkled or crimped. For this, the device is made up of a pressure roller and a shaping roller incorporating a screen with outwardly and inwardly conically tapering openings. The interior surface of the shaping roller is acted upon with a low pressure, as compared with the exterior surface, and can be cooled.