Position control on bottom layers with image processing

Abstract

Summary The invention describes a method for attachment or introduction of valve or cover sheets, imprints, coatings and/or embossings in the correct position on or in components of tube pieces with the following process steps: a) Recording of images of the components of several tube pieces with attached or introduced valve or cover sheets, imprints, coatings and/or embossings,b) Determination of the positions of the valve or cover sheets, imprints, coatings and/or embossings relative to a reference point of the components of the tube pieces,c) Calculation of the deviation of the determined position from the target position andd) Calculation of an average deviation of determined position from the target position over several determined positions ande) Changing of the positions of the valve or cover sheets and components of the tube pieces by the value of the average deviation.

Description

A practical example of the invention follows from the description and drawing.

The individual figures show:

FIG. 1A sketch in which production of sack bottoms is shown.

FIG. 2 View of a sack bottom, indicating the parameters controllable during bottom production.

FIG. 1 a shows a sequence of process steps for formation of a valve bottom on a tubular piece. Each process step is then conducted at an assigned workstation, marked with 1 to 7. The tube pieces 8 are conveyed by a double-belt conveyor 9 to the individual workstations, in which the tube axis runs across the feed direction but in the plane of feed. At workstation 1 the tube end is attached so that the now open bottom 10 lies in a plane that runs essentially orthogonal to the tube axis. At workstation 2 a valve sheet 11 is applied to the open bottom 10. At workstation 3 an additional valve sheet 12 is applied. At workstation 4 areas of the bottom 10 are coated with glue in a manner not further shown. Closing of the bottoms then occurs at workstation 5, in which areas of the bottoms are glued to each other based on the applied glue and thus form a permanent bottom. At workstation 6 a bottom cover sheet 13 is applied to the closed bottom. Then, at workstation 7 an imprint is printed on the bottom cover sheet optionally by means of a format cylinder 14. For this purpose the format cylinder 14 can carry raised plates (not shown).

The double-belt conveyor 9 is shown in FIG. 1b in greater detail. The double-belt conveyor 9 includes two revolving endless conveyor belts 15 guided over idler pulleys 16. For transport of the tube pieces in the areas of the double-belt conveyor the two conveyor belts are placed one above the other and compressed by roll 17 acted upon by spring forces so that displacement of the tube pieces relative to the conveyor belts is avoided. The drive of the conveyor belts 15 is shown as an example for the lower conveyor belt 15. The drive includes a drive motor (not shown), which drives the drive pulley 18. The conveyor belt 15 is guided over pulleys 19, which are arranged so that the conveyor belt 15 wraps around the drive pulley 18 at least over an angle of 180°.

FIG. 2 shows different parameters that are considered during establishment of the position of valve sheet 11, bottom cover sheet 13 and also imprint 20 relative to bottom 8 and which are variable to minimize the manufacturing tolerances in the context of the invention. The reference points of bottom 8 for the corresponding measurements to determine the positions are the vertices 21 of the front bottom triangle viewed in the running direction z and the center line 22 of the bottom, which runs parallel to running direction z. The parameter a₁ denotes the distance of the front edge of the bottom cover sheet 13 from vertex 21, parameter a₂ denotes the distance between vertex 21 and the front edge of the imprint (in the reading direction) and parameter a₃ denotes the spacing between the rear edge of valve sheet 11 from vertex 21. In order to adjust these parameters and minimize their tolerances from the target values, the phase positions of the drive of the transport devices for cover sheet transport and valve sheet transport as well as the phase position of the format rollers 14 relative to the double-belt conveyor are varied. All these components are often driven by a single drive, this drive driving a machine shaft from which the torque to drive the individual transport devices is taken off. In order to be able to change the phase position, a motor-adjustable overlapping drive is provided in which its servomotors can be recorded and regulated in position. If an individual described component has its own drive motor, which operates independently of the machine shaft, the rotational position of this drive motor can be recorded and regulated. This generally occurs via a known rotation sensor.

Parameters b₁ and b₂ denote the distance from the upper edge of the bottom cover sheet and the valve sheet to center line 22. These positions are adjusted by a motor-produced displacement of the transport devices that transport the bottom cover sheet or valve sheet relative to the double-belt conveyor. The same applies for parameter b₄, which denotes the distance between the upper edge of the imprint relative to center line 22, in which for this variation the format roll is displaced axially. Parameter b₃ describes the width of the valve sheet 11.

LIST OF REFERENCE NUMBERS

• 1 Workstation
• 2 Workstation
• 3 Workstation
• 4 Workstation
• 5 Workstation
• 6 Workstation
• 7 Workstation
• 8 Tube piece
• 9 Double-belt conveyor
• 10 Attached bottom
• 11 Valve sheet
• 12 Valve sheet
• 13 Bottom cover sheet
• 14 Format cylinder
• 15 Conveyor belt
• 16 Idler pulley
• 17 Roll
• 18 Drive pulley
• 19 Pulley
• 20 Imprint
• 21 Vertex of bottom triangle
• 22 Center line
• x Direction of tube piece axis
• y Direction orthogonal to transport direction z and to the direction of tube axis y
• z Transport direction of the tube pieces

Claims

1. Method for attachment or introduction of valve or cover sheets, imprints, coatings and/or embossings in the correct position on or in components of tube pieces with the following process steps: a) Recording of images of the components of tube pieces with the attached or introduced valve or cover sheets, imprints, coatings and/or embossings,b) Determination of the positions of valve or cover sheets, imprints, coatings and/or embossings relative to a reference point of the components of the tube pieces,c) Calculation of the deviation of the determined positions from the target positions andd) Changing of the positions of the valve or cover sheets and components of the tube pieces by a value that follows from the determined deviation.

2. Method according to claim 1, characterized by the fact thatthe value that follows from the determined deviation is determined by calculating an average deviation of the determined positions from the target positions over several determined positions.

3. Method according to claim 1, characterized by the fact thatthe value that follows from the determined deviations is determined from a function that describes the deviations of the determined positions from the target positions as a function of time.

4. Method according to the preceding claim, characterized by the fact thatthe function is a periodic function.

5. Method according to claim 1, characterized by the fact thatthe positions of the valve or cover sheets and the components of the tube pieces are determined by means of at least one camera.

6. Method according to claim 1, characterized by the fact thatthe deviation is determined via the number of tube pieces conveyed during one revolution of the transport belt transporting the tube pieces.

7. Method according to claim 1, characterized by the fact thatthe change in position occurs through a motorized differential adjustment.

8. Method according to claim 1, characterized by the fact thatdetermination of the value that follows from the determined deviation is conducted by a computer and control unit.

9. Method according to the preceding claim, characterized by the fact that the computer and control unit also calculates the average deviation and/or the function that describes the deviations of the determined positions from the target position as a function of time.

10. Method according to the preceding claim, characterized by the fact thatthe computer and control unit sends control signals to the differential adjustment.

11. Device for positioning of units for attachment or introduction of valve or cover sheets, imprints, coatings and/or embossings on the components of tube pieces with a device to record images of valve or cover sheets, imprints, coatings and/or embossings and components of tube pieces,an evaluation and computer unit to determine the relative positions of the valve or cover sheets, imprints, coatings and/or embossings relative to components of the tube pieces, and to calculate the relative position from several relative positions or for determination of a deviation function,a memory unit in which the target positions can be stored anda device for adjustment of the relative positions.

12. Device according to claim 11, characterized by the fact that a control unit is provided, which obtains from the computer unit the difference in average relative position and target relative position and with which the device can be supplied with control signals for adjustment.

13. Device according to claim 11, characterized by the fact thatthe device for recording the images includes an optical measurement system, preferably a camera system.