Abstract: A tentering frame is equipped with a tentering chain for the simultaneous treatment of a film web in two directions or in a so-called biaxial manner. The film web is carried by endless tentering chains which hold the film web edges by grippers carried by tentering clamps secured to the tentering chain. The chains have tiltable chain link plates and chain links, whereby the on-center spacing between neighboring clamps is continuously adjustable or variable for changing the chain pitch. In order to reduce the normal pitch when the chain is stretched out as much as possible, and in order to achieve a more efficient pitch adjustment in a larger adjustment range, each tentering clamp is carried by a single shaft which simultaneously functions as one of the two chain pins or chain axles that link two neighboring chain links to each other.

Abstract: A thermoplastic film web is subjected to a defined shrinking in a treatment apparatus with two mirror-symmetrically arranged tentering chains. For this purpose, each chain is equipped with tentering clamps that have a variable on-center spacing or pitch in the travel direction of the tentering chains, and which additionally are position adjustable in a direction other than the travel direction. The entire clamp body or clamp elements may be position variable in a direction other than the travel direction. In operation, the pitch is first reduced in the inlet and/or heating zone of the treatment apparatus. Simultaneously, the clamping position of the individual clamps or clamping element is changed, e.g. by tilting or lifting. The clamp position change takes up extra film web length resulting from the pitch change, whereby the film web assumes throughout its width a corrugated configuration. Then, the film web is cross-stretched.

Abstract: A film stretching machine is also capable of shrinking undulating film by gripping film to be treated at its longitudinal edges by pivotable clips which are disposed spaced apart on a chain conveyor and are guided in a chain conveyor guide. The film is shrunk by a longitudinal adjustment of the film areas lying between the gripping members of neighboring clips. In the apparatus, the longitudinal adjustment or shrinking occurs in that each clip is constructed as a pivoting clip and includes a rolling part on which the gripping part is mounted so as to be pivotable about an axis which is disposed parallel to the film plane.

Abstract: A thermoplastic film stretching apparatus includes a first and a second separate transport chain system including the respective guide tracks and tentering clamps. The tentering clamps are guided without the conventional chain plate connections. The first chain transport system performs the tentering clamp transport from the inlet of the system to the setting zone of the system, where the tentering clamps are released by the first transport chain system and taken over by the second transport chain system. The transport of the tentering clamps by the second system through the setting zone, the cooling zone, and along the way to the outlet zone of the film stretcher, takes place with a smaller transport speed than that of the first transport system. The speed difference between the first and second transport chains is the measure for the film shrinkage to be imposed onto the thermoplastic film.

Abstract: In order to achieve a controlled longitudinal shrinkage of a film web, an adjusting mechanism including a threaded spindle with a cross-piece is provided between neighboring clamping bodies along the tentering chain. The cross-piece is equipped with control rollers that are radially arranged around the longitudinal axis of the threaded spindle and spaced from one another by an angular spacing of, for example, 90.degree. between neighboring control rollers. The control rollers intermittently engage a control rail that has operational segments of a multiple leads screw guide track.

Abstract: A tentering chain is equipped with a mechanism for the stepless, continuous adjustment of the chain pitch which is the on-center spacing between two neighboring chain link journal bolts or pins. Such chains are used for this simultaneous, biaxial treatment of synthetic material films or webs. For this purpose, the chains carry tenter bodies with hooks or clamps for gripping the film edge. The tenter bodies carry guide rollers which engage guide rails along the travel path of the tentering chain. In order to dimension the tenter body with its gripping elements as small as possible, while still permitting a large shrinking or stretching of the film web, the chain link journal bolts or pins are mounted in the respective tenter body for an adjustment of the pin position in a direction of the chain travel. In all positions of the journal pin or pins these pins extend perpendicularly to the longitudinal direction of the chain.

Abstract: A tentering chain is guided between two guide rails extending in parallel to each other. One guide rail (19a) is an outer guide rail with regard to a course followed by the chain, while the other guide rail (19b) is an inner guide rail. The chain links are hinged to each other by a journal pin which carries a first guide roller on an inner pin section between chain link plates, and a second guide roller on a cranked outer pin section. Thus, the rotational axes of these two guide rollers extend in parallel to each other and spaced from each other, so that one guide roller can only contact one guide rail, but not the other and vice versa. This feature prevents the reversal of the rotation direction of the guide rollers as they travel along the parallel guide rails.

Abstract: A tentering chain has a continuously adjustable chain pitch for the simultaneous biaxial treatment of film webs. Tenter bodies conventionally equipped with clamps or hooks for gripping an edge of the film web are carried by the tentering chain. Guide rails operate the tenter clamps. Neighboring tenter bodies are interconnected by chain links. Each chain link is connected by a hinging connection at each end to the respective tenter body. At least one of the two hinging connections of a chain link is adjustable by a hinging bolt having an eccentric section or sections and a circular section or sections. The adjustable eccentric hinging bolts are mounted for rotation in the tenter bodies and the eccentric section engages the respective end of the chain link. For this purpose the chain link has a bore in which the eccentric section is received.