Method of and apparatus for positioning of devices along a bag-making line
AssigneeLemo Maschinenbau GmbH
InventorJakob Schneider
Life of this patent
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Abstract
Devices used in making bags or otherwise carrying out operations on a web of material, such as a plastic web are repositioned based upon a measure of the repeat length of the intermittent advance of the web and comparison of the actual value of that advance with a setpoint value and in accordance with the product of the resulting error and the position of the device along the path of the web. The repositioning can use a positive coupling between a motor on the device and the path either via a rack and pinion for a spindle and nut.
Claims11
A method of positioning a plurality of welding and punching devices for producing bags by successive operations upon a synthetic resin foil web, comprising the steps of:
- (a) positioning a plurality of said devices along a stretch of a path of said web for effecting respective operations on the web in succession;
- (b) intermittently advancing said web along said stretch in increments corresponding to a dimension of a bag to be produced, said devices being positioned along said path at locations spaced by said dimension or a multiple of said dimension;
- (c) detecting changes in movement in the intermittent advance of said web by a sensor;
- (d) repositioning said devices automatically along said path in response to a detected change in the advance of said web;
- (e) comparing an actual value of an intermittent advance of said web with a setpoint value thereof;
- (f) computer-generating a correction value upon deviation of the compared actual value and setpoint value;
- (g) multiplying the correction value by a respective magnitude representing a distance of a respective one of said devices from a fixed reference point of said path to obtain a respective correction product;
- and
- (h) repositioning each of said devices from a previous position by the respective correction product depending upon the distance of the respective device from the fixed reference point.
An apparatus for positioning a plurality of devices for carrying out successive operations upon a web of material, comprising:
- a plurality of said devices positioned at respective locations along a stretch of a path of said web for effecting respective operations on the web in succession
- means for intermittently moving said web along said path past said devices;
- means for detecting changes in movement in the intermittent advance of said web;
- and
- means for repositioning said devices automatically along said path in response to a detected change in the advance of said web, said web of material is a synthetic resin foil web for the making of bags and said devices are welding and punching devices for producing said bags, said web being intermittently advanced in increments corresponding to a dimension of a bag to be produced and said devices are positioned along said path at locations spaced by said dimension or a multiple of said dimension each of said devices being provided with a respective drive for shifting the respective device along said path, said changes in intermittent advance of said web being detected by a sensor responsive to movement of said web, said apparatus further comprising control means for:
- comparing an actual value of an intermittent advance of said web with a setpoint value thereof;
- computer-generating a correction value upon deviation of the compared actual value and setpoint value;
- multiplying the correction value by a respective magnitude representing a distance of a respective one of said devices from a fixed reference point of said path to obtain a respective correction product;
- and
- repositioning each of said devices from a previous position by the respective correction product depending upon the distance of the respective device from the fixed reference point.
Dependencies are inferred from the claim text.