GB2100027A

GB2100027A - Pipe expander

Info

Publication number: GB2100027A
Application number: GB8212415A
Authority: GB
Original assignee: USS Engineers and Consultants Inc
Current assignee: USS Engineers and Consultants Inc
Priority date: 1981-05-01
Filing date: 1982-04-29
Publication date: 1982-12-15
Also published as: IT8267575A0; JPS589733A; DE3215995A1

Abstract

An optical encoder 30 is coupled to positive drive means for an axial pipe feeder 20. A detector 40 adjacent an expander head provides an electrical output at the instant the entry end of the pipe 18 passes thereby. A logic circuit receives the output of the detector and input data for the desired length of pipe to be expanded in the various sequential operations on overlapped portions of the pipe length. A comparator receives binary digital code from the encoder corresponding to the position of the pipe feeder 20 and compares the position of the pipe 18 to calculated stopping positions based upon the actual position of the entry end of the pipe 18 as indicated by the detector 40. <IMAGE>

Description

SPECIFICATION Pipe expander This invention relates to pipe expanders and particularly to apparatus for controlling the sequential operations of the expander on prescribed overlapping portions of the length of the pipe.

Typical pipe expansion apparatus is shown in United States Patent Specification No. 2,780,271.

Prior control systems for this type of expander have utilized rotary shafts having a plurality of spaced cam surfaces which trigger control switches for stopping the feeder assembly at locations corresponding to each cam surface. These controls have been subject to breakdowns, are relatively slow in operation, and do not assure positive repetitive correlation with the actual position of the pipe.

It is therefore a primary object of this invention to provide a control system for mechanical pipe expander apparatus which provides uniform, positive control over the length of pipe expanded in each of sequential work steps performed by the expander on said pipe.

According to the present invention, there is provided a pipe expander comprising a segmented expander head, means for actuating said head to expand the segments thereof, a feeder assembly for axially advancing the pipe onto said head and for retracting said pipe therefrom after expansion, positive drive means for advancing and retracting said feeder assembly, and control means for causing said drive means to advance the pipe in successive steps for expansion of prescribed partially overlapped portions of the length of the pipe, said control means comprising an optical encoder having a rotary disc and including means for providing a binary digital code corresponding to the various angular rotative positions of the disc, a gear reducer coupling said encoder to said positive drive means so that the binary digital code output of said encoder corresponds to the position of said feeder assembly, a detector located adjacent said expander head for providing an electrical output signal signifying the instant the entry end of said pipe passes said detector, a logic circuit for receiving the elctrical output from said detector and calculating the binary digital code of successive locations at which the pipe is to be stopped on said expander head, and a comparator circuit for receiving binary digital code output from said encoder, comparing said code to the calulated codes from said logic circuit, and providing an output signal to said drive means to stop said feeder assembly at the prescribed locations corresponding to the calculated binary digital code therefor.

The invention is further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a pipe expander according to the invention, Figure 2 is a schematic view of a control apparatus of the pipe expander, and Figure 3 is a flow diagram illustrating the steps performed to control the expander.

Referring to Figure 1, a mechanical pipe expander includes a segmented expander head 10 mounted on an arm 12 extending from a support 14. Conveyor rollers 16 are provided for moving a pipe 18 laterally into a carriage 19 which is axially aligned with and adjacent to the head 10. The axial feeder assembly 20 has a clamping jaw 22 for gripping the end of the pipe 18. The jaw 22 is mounted on an arm 24 which is moved in advance and retract fashion by a chain conveyor (not shown) driven by a hydraulic motor (not shown). An optical encoder 30 (Figure 2) is coupled to the hydraulic motor by gear reducers 32 and 34. The encoder 30 is a rotary disc optical encoder of the type described in more detail in British Patent Specification No. 1,369,799 and is desirably an absolute type providing a unique binary digital code output for each of the angular positions of its rotary disc.A suitable absolute encoder is the #5VN233GX made by Baldwin Electronics, Inc. of Little Rock, Arkansas. With such an encoder, it is desirable to provide suitable gear redution so that the disc makes somewhat less than one full 360 degree revolution upon full maximum travel of the arm 24. The encoder is initially set for a known code corresponding to the home, or fully retracted position of the arm 24.

A detector in the form of photocell 40 is provided to indicate the instant when the entry end of the pipe passes thereby. The cell 40 is located in a known position with respect to the head 10 and is used in the calculation of code values for desired step lengths as described hereafter.

Referring to Figure 3, a comparator 50 is provided for receiving input from the encoder 30 in the form of binary digital code values corresponding to the travel positions of the arm 24. A logic circuit 52 is provided for calculating binary digital code values for arm positions corresponding to various lengths of the pipe to be sequentially expanded. The circuit 52 receives input from thumbwheels 54 and 56 set by the operator for the desired lengths of the first and subsequent lengths of the pipe to be expanded.

The first step length will be determined by the code for the arm position when the cell 40 is tripped, plus a code for the distance of cell 40 from the head 10 plus a code for the desired length of the first step to be expanded. Code values for the second and subsequent steps may be calculated by addition of multiples of the input from the second wheel 56. It is desirable to maintain a standard length of first step to obtain round, uniform sized diameter of pipe ends. This makes the pipe ends easier to mate in the field, expediting welding into a pipeline. The second and subsequent steps will be shorter than the first, since a portion of each preceding step is reexpanded.

1. A pipe expander comprising a segmented expander head, means for actuating said head to expand the segments thereof, a feeder assembly for axially advancing the pipe onto said head and for retracting said pipe therefrom after expansion, positive drive means for advancing and retracting said

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Pipe expander This invention relates to pipe expanders and particularly to apparatus for controlling the sequential operations of the expander on prescribed overlapping portions of the length of the pipe. Typical pipe expansion apparatus is shown in United States Patent Specification No. 2,780,271. Prior control systems for this type of expander have utilized rotary shafts having a plurality of spaced cam surfaces which trigger control switches for stopping the feeder assembly at locations corresponding to each cam surface. These controls have been subject to breakdowns, are relatively slow in operation, and do not assure positive repetitive correlation with the actual position of the pipe. It is therefore a primary object of this invention to provide a control system for mechanical pipe expander apparatus which provides uniform, positive control over the length of pipe expanded in each of sequential work steps performed by the expander on said pipe. According to the present invention, there is provided a pipe expander comprising a segmented expander head, means for actuating said head to expand the segments thereof, a feeder assembly for axially advancing the pipe onto said head and for retracting said pipe therefrom after expansion, positive drive means for advancing and retracting said feeder assembly, and control means for causing said drive means to advance the pipe in successive steps for expansion of prescribed partially overlapped portions of the length of the pipe, said control means comprising an optical encoder having a rotary disc and including means for providing a binary digital code corresponding to the various angular rotative positions of the disc, a gear reducer coupling said encoder to said positive drive means so that the binary digital code output of said encoder corresponds to the position of said feeder assembly, a detector located adjacent said expander head for providing an electrical output signal signifying the instant the entry end of said pipe passes said detector, a logic circuit for receiving the elctrical output from said detector and calculating the binary digital code of successive locations at which the pipe is to be stopped on said expander head, and a comparator circuit for receiving binary digital code output from said encoder, comparing said code to the calulated codes from said logic circuit, and providing an output signal to said drive means to stop said feeder assembly at the prescribed locations corresponding to the calculated binary digital code therefor. The invention is further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation of a pipe expander according to the invention, Figure 2 is a schematic view of a control apparatus of the pipe expander, and Figure 3 is a flow diagram illustrating the steps performed to control the expander. Referring to Figure 1, a mechanical pipe expander includes a segmented expander head 10 mounted on an arm 12 extending from a support 14. Conveyor rollers 16 are provided for moving a pipe 18 laterally into a carriage 19 which is axially aligned with and adjacent to the head 10. The axial feeder assembly 20 has a clamping jaw 22 for gripping the end of the pipe 18. The jaw 22 is mounted on an arm 24 which is moved in advance and retract fashion by a chain conveyor (not shown) driven by a hydraulic motor (not shown). An optical encoder 30 (Figure 2) is coupled to the hydraulic motor by gear reducers 32 and 34. The encoder 30 is a rotary disc optical encoder of the type described in more detail in British Patent Specification No. 1,369,799 and is desirably an absolute type providing a unique binary digital code output for each of the angular positions of its rotary disc.A suitable absolute encoder is the #5VN233GX made by Baldwin Electronics, Inc. of Little Rock, Arkansas. With such an encoder, it is desirable to provide suitable gear redution so that the disc makes somewhat less than one full 360 degree revolution upon full maximum travel of the arm 24. The encoder is initially set for a known code corresponding to the home, or fully retracted position of the arm 24. A detector in the form of photocell 40 is provided to indicate the instant when the entry end of the pipe passes thereby. The cell 40 is located in a known position with respect to the head 10 and is used in the calculation of code values for desired step lengths as described hereafter. Referring to Figure 3, a comparator 50 is provided for receiving input from the encoder 30 in the form of binary digital code values corresponding to the travel positions of the arm 24. A logic circuit 52 is provided for calculating binary digital code values for arm positions corresponding to various lengths of the pipe to be sequentially expanded. The circuit 52 receives input from thumbwheels 54 and 56 set by the operator for the desired lengths of the first and subsequent lengths of the pipe to be expanded. The first step length will be determined by the code for the arm position when the cell 40 is tripped, plus a code for the distance of cell 40 from the head 10 plus a code for the desired length of the first step to be expanded. Code values for the second and subsequent steps may be calculated by addition of multiples of the input from the second wheel 56. It is desirable to maintain a standard length of first step to obtain round, uniform sized diameter of pipe ends. This makes the pipe ends easier to mate in the field, expediting welding into a pipeline. The second and subsequent steps will be shorter than the first, since a portion of each preceding step is reexpanded. CLAIMS

1. A pipe expander comprising a segmented expander head, means for actuating said head to expand the segments thereof, a feeder assembly for axially advancing the pipe onto said head and for retracting said pipe therefrom after expansion, positive drive means for advancing and retracting said feeder assembly, and control means for causing said drive means to advance the pipe in successive steps for expansion of prescribed partially overlapped portions of the length of the pipe, said control means comprising an optical encoder having a rotary disc and including means for providing a binary digital code corresponding to the various angular rotative positions of the disc, a gear reducer coupling said encoder to said positive drive means so that the binary digital code output of said encoder corresponds to the position of said feeder assembly, a detector located adjacent said expander head for providing an electrical output signal signifying the instant the entry end of said pipe passes said detector, a logic circuit for receiving the electrical output from said detector and calculating the binary digital code of successive locations at which the pipe is to be stopped on said expander head, and a comparator circuit for receiving binary digital code output from said encoder, comparing said code to the calculated codes from said logic circuit, and providing an output signal to said drive means to stop said feeder assembly at the prescribed locations corresponding to the calculated binary digital codetherefor.

2. A pipe expander as claimed in claim 1, wherein said encoder is an absolute direct reading optical encoder, and wherein said gear reducer has a reduction ratio such that the disc of the absolute encoder will not make more than one full 360 degree revolution over the maximum full length of travel of said feeder assembly.

3. A pipe expander as claimed in claim 1 or claim 2, wherein said detector is a photocell located outward of the entry end of the expander head.

4. A pipe expander constructed and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.