System for controlling tension of a primary backing material in a tufting machine

• US 5,809,917 A
• Filed: 01/15/1997
• Issued: 09/22/1998
• Est. Priority Date: 01/15/1997
• Status: Expired due to Fees

• Current Assignee: Interface Incorporated
• Original Assignee: Interface Incorporated
• Inventors: Gustashaw, David H., McGowan, O. W., Wheeler, Shawn L., Channell, James T., Daley, Daniel H.
• Primary Examiner(s): Nerbun, Peter
• Application Number:
  US08/783,663
• Time in Patent Office: 615 Days
• Field of Search: 112/80.3, 112/80.32, 112/80.01, 112/307, 112/322, 112/220, 242/418.1
• US Class Current: 112/80.32
• CPC Class Codes: B65H 23/1888 and controlling web tension
• CPC Class Codes: D05C 15/14 Arrangements or devices for holding or feeding the base material D05C15/26 takes precedence

Abstract

A system for controlling tension improves carpet quality by maintaining tension along a primary backing material at a constant value. The system controls the tension by maintaining the speed of an entry pin roller slightly slower than the speed of an exit pin roller. The exit pin roller is driven with a main drive motor while the entry pin roller is independently driven by a separate vector drive motor. An encoder, coupled to the exit pin roller, is driven in synchronism with the exit pin roller and produces a pulsed output which is converted into an analog signal representative of the speed of the exit pin roller. A controller receives a user-defined desired value of tension and monitors outputs of a pair of load cells to determine the amount of tension actually on the primary backing material. Based on the difference between the actual value of tension and the desired value of tension, the controller produces a control signal which is fed to a drive circuit. The drive circuit drives the vector motor and, consequently, the entry pin roller at a speed dictated by the analog signal representing the speed of the exit pin roller and the control signal generated by the controller. The quality of the carpet produced by the tufting machine is improved since the stitch density and the carpet pattern may remain substantially constant whereby variations in patterns can be minimized.

Claims

1. A tufting machine for inserting yarn in a backing material, comprising:

a pair of advancing rollers with a first advancing roller for feeding the backing material into the tufting machine and a second advancing roller for removing the backing material from the tufting machine;

a load measuring unit for measuring an actual value of tension generated along the backing material between the pair of advancing rollers and for generating a tension signal representing the actual value of tension;

a drive motor for rotating one advancing roller of the pair of advancing rollers;

a drive circuit for generating a driving signal for driving the drive motor;

a monitoring unit for monitoring a condition of the other advancing roller of the pair of advancing rollers and for generating a condition signal; and

a controller for receiving the tension signal from the load measuring unit and for receiving a predefined value of tension, the controller generating a control signal based on the tension signal from the load measuring unit and the predefined value of tension;

wherein the drive circuit generates the driving signal by combining the condition signal from the monitoring unit and the control signal from the controller, the driving signal for causing the drive motor to rotate the one advancing roller so that the actual value of tension measured by the load measuring unit becomes substantially equal to the predefined value of tension; and

wherein the monitoring unit includes an encoder coupled to the other advancing roller and a frequency to analog converter for converting an output of the encoder to an analog signal that represents a speed of the other advancing roller.

2. The tufting machine as set forth in claim 1, wherein the pair of advancing rollers comprises an entry pin roller and an exit pin roller.

3. The tufting machine as set forth in claim 1, wherein the load measuring unit comprises a load cell.

4. The tufting machine as set forth in claim 3, wherein the load cell is positioned at an entrance to the tufting machine.

5. The tufting machine as set forth in claim 1, wherein the drive motor drives the first advancing roller.

6. The tufting machine as set forth in claim 1, wherein the drive motor controls a speed of rotation of the one advancing roller.

7. The tufting machine as set forth in claim 1, wherein the monitoring unit detects the condition of speed of the other advancing roller.

8. The tufting machine as set forth in claim 1, wherein the controller generates the control signal based on a difference between the output from the load measuring unit and the predefined value of tension.

9. The tufting machine as set forth in claim 1, wherein the controller includes an input interface for receiving the predefined value of tension.

10. The tufting machine as set forth in claim 1, wherein the controller includes a output interface for displaying the actual value of tension on the backing material.

11. An apparatus for controlling a machine-direction tension in an advancing web of carpet primary backing material passing through a tufting machine, comprising:

means for advancing the web of carpet primary backing material through the tufting machine;

means for measuring the machine-direction tension in the advancing web of carpet primary backing material; and

means for controlling the advancing means so that the measured machine-direction tension remains substantially equal to a predetermined quantity of tension as the web of carpet backing material is being advanced through the tufting machine;

wherein the advancing means comprises a first pin roller driven by a first drive motor for introducing the web of carpet backing material into the tufting machine and a second pin roller driven by a second drive motor for removing the web of carpet backing material from the tuffing machine; and

wherein the controlling means comprises;

an encoder for tracking a rotation of the second pin roller;

a frequency to analog converter for receiving an output from the encoder and for generating an analog speed signal representative of a speed of rotation of the second pin roller;

a controller for generating a control signal based on a comparison between the measured machine-direction tension from the measuring means and the predetermined quantity of tension; and

a drive circuit for generating a drive signal for driving the first drive motor, the drive circuit producing the drive signal based on a combination of the analog speed signal from the frequency to analog converter and the control signal from the controller.

12. The apparatus as set forth in claim 11, wherein the controlling means controls one of the first drive motor or second drive motor so that the web of carpet backing material has the predetermined quantity of tension.

13. The apparatus as set forth in claim 11, wherein the measuring means comprises a load cell for measuring the machine-direction tension in the web of carpet backing material.

14. The apparatus as set forth in claim 11, wherein the controlling means controls the advancing means so that a first speed at which the web of carpet backing material is introduced into the tufting machine is slower than a second speed at which the web of carpet backing material is removed from the tufting machine.