Claims
- 1. Apparatus for aligning a ply of material moving in a prescribed direction and preferably through a desired path of travel prior to stitching at a sewing head in a sewing machine, said apparatus comprising:
- guide means for applying a force to said ply having a component in a direction transverse to said prescribed direction;
- two or more sensing means, each located at a point which is a distance D.sub.n in said travel path ahead of said sewing head for sensing the transverse position of said ply at the point relative to the desired transverse position at said point, in the travel path;
- means for weighting the outputs from said sensing means;
- means for combining said weighted outputs in a predetermined way; and
- means responsive to the combined, weighted sensing means outputs for generating a control signal to said guide means for said transverse force component to maintain said ply within the desired travel path at least at said sewing head.
- 2. Apparatus as claimed in claim 1 wherein said means for weighting weights said sensor outputs inversely to the distance D.sub.n of each sensor.
- 3. Apparatus as claimed in claim 2 wherein said means for combining operates in accordance with the formula: ##EQU2## where G is an indicator of transverse component;
- E.sub.n is the error in transverse position sensed at sensing means n; and
- N is the number of sensing means.
- 4. Apparatus as claimed in claim 3 wherein said means for weighting linearly weights the errors E.sub.n sensed by the sensing means.
- 5. Apparatus as claimed in claim 1 wherein each sensing means generates an error output indicative of the difference between the sensed transverse position of the ply and the desired transverse position; and
- wherein said weighting means weights said error outputs in accordance with a predetermined arithmetic progression.
- 6. Apparatus as claimed in claim 1 including means for indicating the rate at which said ply is moving through its travel path; and
- wherein said control generating means is also responsive to said rate indicating means.
- 7. Apparatus as claimed in claim 1 wherein said guide means is a friction wheel, the angular position of which determines said transverse force component.
- 8. Apparatus as claimed in claim 7 including means for indicating the rate at which said ply is moving through its travel path;
- wherein said control generating means controls the angle of said wheel; and
- wherein the rate at which said control generating means controls the wheel angle is a function of the rate indicated by said rate indicating means.
- 9. Apparatus as claimed in claim 1 wherein there is a first sensing means located between said sewing head and said guide means and a second sensing means located along the travel path on the opposite side of said guide means.
- 10. Apparatus as claimed in claim 9 wherein said ply is aligned along a lateral edge; and
- including means for adjusting the transverse position of at least said second sensing means so that said second sensing means is centered at the desired transverse location of said edge at the lateral point in the travel path where said second sensing means is located.
- 11. Apparatus as claimed in claim 9 wherein said ply is aligned along a curved lateral edge thereof; and
- wherein said desired travel path tracks said curved lateral edge.
- 12. Apparatus as claimed in claim 1 including means for adjusting the lateral position of at least one of said sensing means.
- 13. Apparatus as claimed in claim 1 wherein, when said guide means is in a home condition, it normally applies no transverse force component to said ply; and
- wherein said control generating means includes means for causing said guide means to have a predetermined transverse force component in the home condition.
- 14. Apparatus as claimed in claim 13 wherein said guide means is a friction wheel, the angular position of which determines said transverse force component; and
- wherein said causing means causes said friction wheel to assume a predetermined angular position when in its home condition.
- 15. Apparatus as claimed in claim 1 wherein said sensing means includes a light source positioned on one side of said ply and a linear photosensor array mounted to received light from said source on the opposite side of said ply from said light source, said linear array being at a slight angle to the transverse of said path of travel.
- 16. Apparatus as claimed in claim 15 wherein said ply is aligned along a lateral edge thereof; and
- wherein said photosensor array is substantially centered at the desired transverse position of said lateral edge at the point in said path of travel where said sensing means is located.
- 17. Apparatus as claimed in claim 1 wherein said guide means is a friction wheel, the angular position of which determines said transverse force component;
- wherein when said friction wheel is in a home position, it is angled in said prescribed direction; and
- including a homing disc mounted to rotate with changes in angular position of said wheel, a home position slot in said disc, means for sensing an edge of said slot, means operative when an edge of said slot is detected for backing up said disc slightly, means operative if another edge is detected when said disc is backed up for utilizing the position of the other edge as the home position, and means operative if another edge is not detected for returning to the detected edge and utilizing the returned to position as the home position.
- 18. Apparatus as claimed in claim 1 including means for adjusting the lateral position of at least one of said sensing means.
- 19. Apparatus as claimed in claim 1 wherein said apparatus is utilized to align an upper and a lower ply to be stitched together;
- wherein the are separate guide means and separate sensing means for each of said plies; and
- wherein the transverse force components of said guide means are independently controlled.
- 20. In an apparatus for aligning a ply of material moving in a prescribed direction through a desired path of travel to be stitched at a sewing head in a sewing machine, a guide means for applying a transverse force to said ply comprising:
- a substantially straight arm adjacent said ply extending in a direction transverse to said travel path and beyond a lateral edge of said ply;
- means for pivotably mounting said arm at a point along the arm closer to the extending end of the arm than to the other end of the arm, but not at the extending end;
- means for mounting a friction wheel having an adjustable angular position near the other end of said arm and adjacent said ply;
- means for normally biasing said arm to a position where said friction wheel is out of contact with said ply; and
- means for applying a selected force to the extended end of said arm in a direction to press said friction wheel against said ply with a predetermined pressure.
- 21. Apparatus as claimed in claim 20 including means for maintaining said predetermined pressure applied to the ply constant regardless of changes in operating conditions of said sewing machine.
- 22. Apparatus as claimed in claim 20 wherein said force applying means is a pneumatic cylinder which presses a piston mounted pin against said arm.
- 23. Apparatus as claimed in claim 22 including means for controlling the force applied to the arm by said cylinder to control the amount of said predetermined pressure.
- 24. Apparatus as claimed in claim 23 wherein said means for controlling includes a manual pressure control, a pressure sensor and a visual pressure indicator.
- 25. Apparatus as claimed in claim 22 wherein said pressure is controlled to compensate for variations in ply thickness.
- 26. Apparatus as claimed in claim 22 wherein said pressure is controlled to control stretching of said ply.
- 27. Apparatus as claimed in claim 20 wherein said means for normally biasing is a compression spring mounted between the pivot point of said arm and the friction wheel.
- 28. Apparatus as claimed in claim 20 including means for sensing the transverse position of said ply at one or more selected positions along said path of travel; and
- means for mounting said sensing means so that the sensing means is minimally influenced by bounce or other movement of said friction wheel and said arm.
- 29. Apparatus as claimed in claim 28 including a stationary member adjacent said arm, said ply passing between said member and arm;
- means for pivotably mounting at least a portion of said sensing means to said member;
- means for normally biasing said pivotably mounted portion away from said member; and
- means responsive to said arm being moved to cause said friction wheel to apply pressure to said ply for applying a force to move said sensing means portion to an operative position adjacent said ply.
- 30. Apparatus as claimed in claim 29 wherein the means applying force to move the sensing means includes a spring loaded pin mounted to said arm, whereby movement of said arm does not result in a corresponding movement of said sensing means.
- 31. Apparatus as claimed in claim 20 wherein said apparatus is utilized to align an upper and a lower ply to be stitched together at said sewing head, and wherein there is a separate pivotably mounted arm, friction wheel, biasing means and force applying means for each of said plies.
- 32. A method for aligning a ply of material moving in a prescribed direction and preferably through a desired path of travel prior to stitching at a sewing head in a sewing machine, the method comprising the steps of:
- sensing the transverse position of said ply at at least two points in said travel path;
- weighting the results of the sensing step;
- combining the results of the weighting step in a predetermined way; and
- utilizing the results of the combining step to control a transverse force component applied to said ply by a guide means, said transverse force component modifying the alignment of said ply.
- 33. A method as claimed in claim 32 wherein said means for weighting weights said outputs inversely to the distance D.sub.n of each output.
- 34. A method as claimed in claim 33 wherein said combining step is performed in accordance with the formula: ##EQU3## where G is an indicator of transverse component;
- E.sub.n is the error in transverse position sensed at sensing means n; and
- N is the number of sensing means.
- 35. A method as claimed in claim 32 wherein said weighting step weights sensed error from said sensing step in accordance with a predetermined arithmetic progression.
- 36. A method as claimed in claim 32 including the steps of determining the rate at which said ply is moving through its travel path; and
- utilizing the results of said determining step during said control step.
- 37. A method as claimed in claim 32 wherein said ply is aligned along a curved lateral edge thereof; and
- wherein said desired travel path tracks said curved lateral edge.
- 38. Apparatus for aligning a ply of material moving in a prescribed direction and preferably through a desired path of travel prior to stitching at a sewing head in a sewing machine, said apparatus comprising:
- guide means for applying a force to said ply having a component in a direction transverse to said prescribed direction;
- sensing means located at a point in said travel path ahead of said sewing head for sensing the transverse position of said ply at the point relative to the desired transverse position at said point;
- means for weighting the output from said sensing means; and
- means responsive to the weighted sensing means output for generating a control signal to said guide means for said transverse force component to maintain said ply within the desired travel path at least at said sewing head.
- 39. Apparatus as claimed in claim 38 wherein each sensing means generates an error output indicative of the difference between the sensed transverse position of the ply and the desired transverse position; and
- wherein said weighting means weights said error outputs in accordance with a predetermined arithmetic progression.
RELATED APPLICATIONS
This application is a continuation-in part of application Ser. No. 07/052,577, filed May 20, 1987, which will issue as U.S. Pat. No. 4,825,787 on May 2, 1989 and is entitled "Method And Apparatus For Guiding Fabric To A Sewing Machine".
US Referenced Citations (6)
Foreign Referenced Citations (1)
Number |
Date |
Country |
1464180 |
Feb 1977 |
GBX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
52577 |
May 1987 |
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