BACKGROUND OF THE INVENTION
[0001] The present invention concerns an apparatus for producing stamped sections in a strip
blank which is advanced continuously lengthwise past a stamping tool positioned to
one side of the strip and arranged to cooperate with a support roll. The support roll
is mounted on a shaft positioned on the side of the strip opposite the stamping tool
in parallel with the plane of the strip and perpendicularly to the direction of advancement
of the strip.
[0002] Stamping operations of the kind defined above are used for instance to produce threads
in the strip of hose clamps of the type wherein the strip passes through a screw-worm
sleeve in engagement with a screw-worm positioned therein.
[0003] The threads are usually produced through stamping in a large eccentric-shaft press
which in a single operation forms all the thread grooves in a section of the strip.
The stamped section is subsequently severed off the strip blank and shaped into the
strip of the hose clamp. During the stamping operation in the eccenter press some
flow of material occurs transversely relative to the lengthwise extension of the strip.
This material flow increases the width of the strip by approximately 5%, with the
result that the screw-worm sleeve tolerances need to be comparatively large. The difference
in width between stamped and unstamped sections of the continuously advanced strip
blank also is disadvantageous in that it makes it complicated to guide the strip,
causes increased wear on the tools as well as operational disturbances.
[0004] The purpose of the present invention is to effect the stamping of the strip blank
without causing noticeable differences in width between the stamped and unstamped
sections of the strip blank while at the same time making it possible to effect the
stamping at a high rate of production.
SUMMARY OF THE INVENTION
[0005] The apparatus in accordance with the invention is characterised in that the shaft
is arranged to be turned between two end positions and in that the support roll is
eccentrically mounted on the shaft and arranged by turning said shaft to one of the
end positions, to urge the strip against the stamping tool and, by turning the shaft
to the opposite end position thereof, to allow the strip to pass past the stamping
tool out of contact with the latter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The invention will be described in closer detail in the following with reference
to one embodiment thereof illustrated in the accompanying drawings, wherein
Fig. 1 is a perspective view of a stamping apparatus in accordance with the invention,
and
Figs. 2 and 3 are lateral views of the apparatus, illustrating the latter in two different
operational positions.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0007] A strip blank 1 which is to be stamped along its length with thread-groove, sections
and which in a subsequent operation is to be severed and shaped into a hose clamp
strip, is continuously advanced by a pair of rollers 2 past a support roll 3. The
support roll 3 is mounted on an eccentric shaft 4 which is positioned in parallel
with the plane of the strip and perpendicularly to the direction of advancement of
the latter.
[0008] A stamping tool 5 the stamping face of which is formed to give the desired thread
profiles is positioned on the opposite side of the strip 1 and is attached to a slide
member 6 which is mounted for displacement in a plane which is essentially parallel
to the plane of advancement of the strip. A bracket 7 mounted on the slide member
6 supports the piston rod of a piston-and-cylinder unit 8 arranged to displace the
slide member to and fro. A second piston-and-cylinder unit 9 is secured to the eccentric
shaft 4 via a lever.10. When the shaft 4 is turned with the aid of the lever 10 and
the piston-and-cylinder unit 9 the support roll 3 may be.displaced transversely relative
to the direction of advancement of the strip 1 towards or away from the stamping tool
5 between two end positions.
[0009] In the inner end position of the tool illustrated in Fig. 2 the support roll 3 presses
the strip 1 hard against the stamp tool 5. At the same time the slide member 6 is
displaced by the piston-and-cylinder unit 8 in synchrony with the advancement of the
strip by the pair of rollers 2, the stamping action being effected in the press nip
between the support roll 3 and the stamping tool 5.
[0010] When one thread section has been stamped, which is sensed by means provided to sense
the movements of the slide member 6, by a time relay or by means arranged to sense
the advancement of the strip, the second piston-and-cylinder unit 9 is activated,
which by turning the shaft 4 in the opposite direction effects displacement of the
support roll 3 away from the stamping tool 5. As a result the strip 1 is no longer
pressed against the stamping tool and the tool is allowed to complete its movement
forwards out of contact with the strip 1. The stamping tool is then brought back to
its original position by the piston-and-cylinder unit 8 to effect another stamping
operation. The strip 1 is advanced continuously at a constant rate and when one strip
section having a length corresponding to the desired gap between two threaded sections
has moved past by the support roll 3 the piston--and-cylinder unit 9 is again activated
and serves to press the support roll against the stamping tool 5 to effect another
stamping operation.
[0011] The length of the stamped sections and the length of the unstamped sections separating
them are easily varied by controlling the operation of the piston-and--cylinder 9
in such a manner that the support roll 3 when abutting against the stamping tool at
one end position of the stamping tool provides the desired length of the stamped section
whereas the desired interruption between the stamped sections is effected in the other
end position.
[0012] Because the stamping operations are effected successively over a short section of
the length of the strip 1 most of the flow of the material will take place in the
lengthwise direction of the strip whereas the difference in width will be minimal.
[0013] The invention is not limited to the embodiment described in the aforegoing but modifications
thereof are possible within the scope of the appended claims. The means for advancement
of the stamping tool 5, for example, are not essential, it being possible to shape
the tool as a round stamping cylinder mounted on a shaft which is driven in synchrony
with the speed of advancement of the strip. Other means than piston-and-cylinder units
may be used to effect the movements of the slide member 6 and to operate the shaft
4.
1. An apparatus for producing stamped sections in a strip blank (1) which is advanced
continuously lengthwise past a stamping tool (5) positioned to one side of the strip
and arranged to cooperate with a support roll (3), said roll being mounted on a shaft
(4) positioned on the side of the strip (1) opposite the stamping tool (5) and in
parallel with the plane of the strip perpendicularly to the direction of advancement
of the latter, characterised in that the shaft (4) is arranged to be turned between
two end positions and in that the support roll (3) is eccentrically mounted on said
shaft and arranged, by turning said shaft to one of the end positions thereof, to
urge the strip (1) against the, stamping tool (5) and, by turning the shaft (4) to
the opposite end position thereof, to allow said strip to pass past the stamping tool
out of contact with the latter.
2. An apparatus as claimed in claim 1, characterised in that the stamping tool (5)
is elongate and straight and is provided with means (6, 7, 8) to advance said tool
in synchrony with the advancement of the strip (1) during the stamping of a section
of said strip and to return said tool to the original position thereof after completion
of the stamping of the section.