US3822831A

US3822831A - Apparatus for straight line oscillation of a wire guide

Info

Publication number: US3822831A
Application number: US00294624A
Authority: US
Inventors: A Marcum
Original assignee: Price Brothers Co
Current assignee: Price Brothers Co
Priority date: 1972-10-03
Filing date: 1972-10-03
Publication date: 1974-07-09
Anticipated expiration: 1991-07-09
Also published as: CA1016520A

Abstract

Apparatus for oscillating a wire guide carried by a wire feed carriage which moves axially of a rotating concrete pipe core to apply prestressing wire to the core. The oscillating mechanism includes a four bar pantograph with the wire guide mounted on one end of one link of the pantograph to provide straight line movement of the wire guide parallel to the axis of the core being wrapped as the wire guide is oscillated.

Description

lJn-ited States Patent Marcum, Jr.

[ Jul 9, 1974 [54] APPARATUS FOR STRAIGHT LINE 3,052,419 9/1962 Huck 242/722 OF A W GUIDE ZE'fi 2/1221 8212 1;; 12118 g1 [7 v n glgr M m,Jr-, n rv1ll 3,724,768 4/1973 Breitfuss et al. 242/722 x [7 Assigneel Price Brothers p y Dayton, Primary Examiner-Stanley N. Gilreath 3 Ohm 4. 9145284891 11. 9'1IEUWIEFPPQLHEKEEQQB2581. [22 Filed: 061. 3, 1972 [21] Appl. No.1 294,624 57 ABSTRACT Apparatus for oscillating a wire guide carried by a f ii ig i wire feed carriage which moves axially of a rotating g concrete pipe core to apply prestressing wire to the [58] Field of Search 242/721, 7.22, 7.23, 7.01,

242/158 R 158 F 158 B 158 2 158 4 core. The osclllatmg mechamsm mcludes a four bar 4 a anto a h with the wire uide mounted on one end 138/172 176 p P g of one link of the pantograph to provide straight line movement of the wire guide parallel to the axis of the [56] u TE g gr xggs ggENT's I core being wrapped as the wire guide is oscillated. 3,039,707 6/1962 Beck et al 242/I5 .2-x 8 Claims, 6 Drawing Figures HYIgmUPLIC 22 v J20 2 38 46 SERVO AMPLIFIER PIPE SIZE CONTROL I I2 BEVELLENGTH ANALOG T0 FULL z I I I "CONTROL DIGITAL R g 4 i (N SELECT) CONYERTE 54 52 V r'fi'fi" LINEARIZING sYNcRo 3 BY 556 51311 NETWORK "-34 TRANSMITTER 6 j I R0 to MULTIPLYING DIFEQRCETGQTIAL l lrE /COS DIGITALTO ANALOG TRANSMITTER CONVERTER CONVERTER 32 LE 26 3 0 as 28 I I PAIENTEDJUL 919m SHEEY 2 0F 3 m wE SHEET 3 BF 3 FIG IHII

APPARATUS FOR STRAIGHT LINE OSCILLATION OF A WIRE GUIDE BACKGROUND OF THE INVENTION Prestressed concrete pipe is made by wrapping prestressing wire under tension about a pipe core. In the majority of pipe sections manufactured, the ends of the pipe extend at right angles to the longitudinal axis of the pipe. In some case, however, particularly where it is desiredto make a slight change in grade or direction of the pipe line as .it is installed, one end'of the pipe section may be slanted, or bevelled, with respect to the longitudinal axis of the pipe. Pipe sections of this type are referred to as bevel pipe.

Bevel pipe will either be full bevel or half bevel. In a full bevel pipe the longer side is l inch longer for each foot of internal diameter than the shorter side. For example, in a 48 inch, full bevel pipe, the longer side is 4 inches longer than the short side, while in a 36inch full bevel pipe the longer side is 3 inches longer than the shorter side. In a half bevel pipe the long side of the pipe is one-half inch longer for each foot of internal diameter than the short side of the pipe.

It will be apparent that in wrapping prestressing wire on bevel pipe, although the spacing between adjacent wraps should be uniform along a major portion of the length of the pipe, some variation in spacing between adjacent wraps on the long and short sides of the pipe must be made atthe bevelled end to accommodate the difference in lengths between the opposite sides of the pipe.

In the past this variation in spacing has been accomplished by the machine operator visually checking the spacing between adjacent wire wraps and jogging the wire wrap carriage at the bevel end of the pipe to provide unequal spacing of the wire wraps at the long and short sides of the pipe.

More recently, apparatus has been designed for eliminating the necessity of relying on operator judgment I for obtaining the desired wire wrap spacing on the pipe. In apparatus of this type a pivotally mounted arm carrying a wire guide at one end is automatically oscillated by control mechanism as the carriage on which the arm is mounted moves along the bevel end of the pipe core being wrapped. For example, see U.S. Pat. Nos. 3,052,419; 3,052,226; and 3,587,659.

It will be noted, however, that where variation in wrap spacing is obtained by feeding the wire through guide sheaves attached to a pivotally mounted arm, an additional, unwanted variation is introduced, since the guides sheaves are not moving parallel to the pipe core but in an arc. This becomes particularly noticeable where pipe cores of large diameter are being wrapped.

It will be seen, therefore, that with mechanism of this type, either the variation in wrap spacing from that desired which results at the bevel end must be acceptable or, control mechanism must be provided that can compensate for these deviations by controlling other variables of the process.

SUMMARY or THE INVENTION Bevel wrapping apparatus in accordance with the present invention provides a system for automatically wrapping bevel pipe wherein the oscillation of a wire guide carried by a wire feed carriage moving parallel to the axis of the pipe core is oscillated with a straight line movement which is also parallel to the core axis. As a result, variations in wrap spacing from the spacing desired, which would occur if the wire guide was merely carried by a pivoted link, are avoided.

The wire guide incorporates a four bar pantograph mechanism in which a feed link carries the wire guide and is actuated by a drive link powered by a double acting hydraulic or pneumatic piston and cylinder. To insure that the outer end of the feed link moves with a straight line motion, pairs of rollers having mutually perpendicular axes are mounted on the drive link and run along trackways extending perpendicular to each other but parallel to the axis being wrapped.

The rollers are mounted on the drive at the point of intersection'of the drive link with a line passing through a fixed pivot connection of two other links of the system and the wire guide sheaves. As a result, the linkage system provides a true axial movement of the wire guide sheaves, eliminating both inaccuracy in wrap spacing at the bevel end of the pipe and the necessity of providing additional control mechanism to compensate for nonlinear movement of the wire guide sheaves.

BRIEF DESCRIPTION THE DRAWINGS FIG. 1 is a block diagram of the system of the present invention;

FIG. 2 is a side view of the bevel wire control mechamsm;

FIG. 3 is a rear view of the mechanism of FIG. 2;

FIG. 4 is a view taken on line 44 of FIG. 3;

FIG. 5 is a view taken on line 5-5 of FIG. 4; and

FIG. 6 is a perspective view of the pantograph linkage of the bevel wire control mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring initially to the simplified block diagram shown in FIG. I of the drawings, it will be seen that, in accordance with the present invention, a pipe 10 is placed on a platform 12 to be rotated by a drive mechanism 14. The drive mechanism also supplies power through a variable ratio drive 16 to a carriage drive mechanism 18 driving a wire feed carriage 20. The variable ratio drive therefore controls the pitch of the wire at it is wrapped onto the pipe by controlling the rate at which the carriage 20 moves vertically as the pipe is rotated.

A bevel wire control mechanism, shown generally at 22, is mounted on carriage 20, and, as described below in detail, applies the wire wraps to the pipe 10. For present purposes it will be noted that the bevel wire control mechanism is so designed that the point at which the wire is fed from the mechanism to the pipe moves parallel to the axis of the pipe. This is especially important when wrapping wire on large diameter pipe (e.g. 196 inch pipe).

The rotational position of the pipe is sensed by a syncro transmitter 24 (Vernitron Corp., type VCX 23/ 36- 6C), the rotor of which makes one revolution for each revolution of the pipe. Thesyncro transmitter 24 is electrically connected to a syncro differential transmitter 26 (Vernitron Corp. type VCDX 23/38-6C). The rotor 28 of the syncro differential transmitter does not rotate with the rotor of snycro transmitter 24 but is a fixed rotor which may be adjusted initially by the operator to align the syncro transmitter 24 electrically with the orientation of the pipe so that the pipe and the syncro signals are properly aligned at the beginning of a wire wrap operation.

Each pipe is initially mounted for wrapping with its wire anchor, located on the long side of the pipe, at the point of tangency of the wire from the bevel wire control 22. Due to the large size of the pipe and the consequent difficulty in placing the pipes on the platform 12 precisely, an electrical correlation between the pipe position and the syncro transmitter is provided by the manual positioning of the rotor 28.

The electrical output of the syncro differential transmitter 26 is a representation of the angle of the pipe with respect to its starting position. This output is connected to a sine/cosine converter 30 (Natel Engineering, type 43l-3B-60-115), the outputs of which are electrical signals representing the sine and cosine of the angle of the pipe with respect to its starting position, these signals being of a predetermined amplitude and of a frequency equal to the rotational frequency of the pipe.

One output of the sine/cosine converter 30 (e.g., the cosine output) is applied to a summing amplifier 32 whereit is combined with a signal from a linearizing network 34. The output of the linearizing network 34 is a signal which is a function of pipe diameter and is used to provide an offset voltage to allow this invention to accommodate an extremely large range of sizes. The output of the summing amplifier 32 is applied as an input to a multiplying digital to analogue converter 36 (Data Device Corp., type UDAC-l1-3). The output waveform of converter 36 is identical to its input from amplifier 30 except that the output waveform is reduced in amplitude by a ratio which is initially determined by pipe size and thereafter reduced progressively as wire is wrapped onto the pipe.

The output waveform from converter 36 is applied as one input to a second summing amplifier 38. The other input to the amplifier 38 is a signal generated by a linear variable differential transformer (LVDT)40 (mfg. by Schaevitz), the output of which represents the position of a hydraulic piston in a bevel wrap control 22. The difference between the control signal from converter 36 and the actual position signal from LVDT 40 is an input signal to servo amplifier 42 (Analog Devices, Inc., type 408). The output of the servo amplifier 42 controls a servo valve 44 which in turn controls hydraulic fluid from a hydraulic pump 46 to the bevel wrap control 22. This, as will presently be explained in detail, causes a feed link of the control 22 to follow or track the control signal output of the digital to analogue converter 36 and therefore will position the wire relative to the carriage mechanism under the control of that signal.

. A pipe size control 50 is provided to permit the invention to accommodate pipe of various sizes. The pipe size control 50 is a -turn potentiometer which provides means for presetting the initial amplitude of the output signal from the digital to analogue converter 36. The potentiometer is connected to an amplifier 52 which is selectable in the embodiment of the invention shown herein to have a gain either of one-tenth or onetwentieth. A gain of one-tenth corresponds to a full bevel position of switch 54 while a gain of onetwentieth corresponds to a half bevel position of the switch. Amplifier 52 is connected to an analogue to digital converter 56 (Datel, type ADC-E123) which continuously converts the analogue input from amplifier 52 into a 10 bit digital or binary word. This 10 bit word is used as a preset input to up-down counter 58.

The position of the wire feed carriage 20 is monitored by an output shaft encoder 60 which produces a predetermined number of pulses for each increment of movement of the carriage. These pulses are applied to a divide by N counter 62. The value of N is determined by the length of the bevel to be applied to the pipe 10 and may be selected by a selector switch 64. In the embodiment shown in FIG. 1, the number N may be any integer from one to 63.

Switch 64 is actually a six position selector switch which is used to select the

integers

2, 4, 8, 16, 32 and 63. The larger the value of N, the greater the number of pulses (representing a greater length of travel of the carriage) which will be required to be applied to the up-down counter 58 to reduce its present value (as detennined by the pipe size control 50) to zero. Once the preset counter reaches the value of zero, the output of the digital to analogue converter 36 will also be zero which therefore terminates the bevel wrap operation.

Turning now to FIGS. 2 through 6 of the drawings, the bevel wire control mechanism 22 will be described. As seen in FIG. 6 of the drawings, the bevel wire control mechanism includes a pantograph linkage which consists of a feed link 72, a drive link 74, a spacer link 76 and a guide link 78. The drive link 74 is formed as a pair of side plates 80 joined by a cross bar 82 and having openings 84 therethrough for the reception of a shaft 86 which pivotally attaches thereto the feed link 72 intermediate its ends.

The spacer link 76 is bifurcated at one end thereof to provide a pair of arms 88 having openings therethrough to receive pivot shafts 92 which pivotally attach the bifurcated end of the spacer link to the upper ends of the side plates 80 of the drive link 74. At its opposite end the spacer link is pivotally mounted between the spaced side plates 94 of the guide link 78.

The side plates of guide link 78 are joined by a cross bar 96 and a shaft 98 extends through openings in the upper ends of the side plates 94 and an opening in one end 102 of the spacer link 76. The end 104 of the feed link 72 is provided with an opening therethrough and is received between the lower ends of the side plates 94, with the opening in feed link 72 aligned with openings 106 in the side plates 94. A shaft 108 passes through the aligned openings in

links

72 and 78 to form a pivotal attachment between them at this point.

The opposite end of the feed link 72, as seen in FIGS. 2 and 3, has a grooved guide sheave 110 rotatably mounted thereon and a guide sheave link 1 12 pivotally attached thereto, as at 114. The guide sheave link 112 includes a pair of side plates 116 interconnected at their upper ends by cross bar 118 and an abutment member 120. Joumalled between the lower ends of the side plates 116 is a second grooved guide sheave 122. Mounted on an upper surface of the feed link 72 is a threaded block 124 receiving an attaching bolt 126 which bears at one end against the abutment 120. With this construction it will be seen the spacing between the grooved guide sheaves 110 and 122 may be adjusted.

Turning now to FIGS. 2 through 5, it will be seen that the wire bevel control mechanism also includes a supporting framework 128, on which is mounted a hydraulic piston and cylinder 130 by means of the trunion 132 and a pillow block 133. A .piston rod 134 protrudes from the lower end of the cylinder 135 and is attached at its inner end to a piston, not shown. The hydraulic piston and cylinder 130 is of the double acting type, for example, the type manufactured by the Parker Hannifin Company No.

At its lower end the piston rod is threaded and received in an internally threaded knuckle 136. The lower end of knuckle 136 is of split construction and receives a cross shaft 137 therethrough with the split end of the knuckle being clamped to the shaft 137 by means of bolts or the like 138. Ourwardly' of the knuckle 136 the shaft is joumalled, as at 140, in the side plates 80 of the drive link 74.

At its outer ends the shaft 137 has attached thereto roller brackets 142. Each bracket 142 rotatably supports a pair of rollers 144 which engage trackways 146 on the supporting framework 128. Each bracket 142 also journals a second pair of rollers 148 which engage trackways 150 extending parallel to trackways 146 but disposed perpendicularly thereto.

Bearing blocks 152 are mounted on one face of the supporting framework 128 by means of bolts 154 passing through slotted openings 155 in the bearing blocks. A pair of adjusting bolts 156 are threaded through blocks 158 and bear on a lower surfaces of the bearing blocks 152 to provide a limited amount of vertical adjustment. As best seen in FIG. 2 of the drawings, outer ends of the shaft 98 are joumalled in bearing blocks 152 to pivotally attach the linkage 70 to the supporting framework 128.

As noted above, theflow of pressurized fluid to opposite sides of the piston of the hydraulic piston and cylinder 130 is controlled through the servo valve 44, which, as seen in FIG. 4 of the drawings, directs flow alternatively through

pressure lines

162 and 164. Movement of the piston within the cylinder 135 is sensed by means of the LVDT 40, since its probe 166 is directly connected through arm 168 to an upwardly projecting rod 170 attached to the piston.

With the above construction, it will be seen that the servo valve 44 may direct pressurized fluid to either side of the piston and cylinder 130 through the

lines

162 and 164, causing the piston to move within the cyl- 1 inder. This movement is sensed by the LVDT 40 which transmits a signal to the amplifier 38 representing the position of the piston in the cylinder.

Movement of the piston rod 134 in a vertical plane is transmitted to the drive link 74 by means of the knuckle 136 and shaft 137. Since the intersection of the

links

76 and 78 is fixed and since the guide end of the feed link 72 and the axes of

shafts

137 and 98 lay on a straight line, movement of the outer end of the feed link 72 will be parallel to the movement of the shaft 137 in accordance with well known principles of pantograph operation.

Additionally, since the shaft 137 is restrained by the

rollers

144, 148 and cooperating trackways on the sup porting framework 128 and can only move in a vertical direction, the guide end of the feed link also is capable of only vertical movement. As a result, the guide end of the feed link moves axially of the pipe 10 being wrapped rather than in an arc, as would be the case if a pivotally mounted arm were utilized.

From the above construction, it will be seen that the present inventionprovides wire wrapping mechanism which provides for infinite adjustability with respect to pipe diameter and the amount of bevel of the pipe being wrapped and in which the wire guide mechanism v wire wraps at the bevel end of said core varying from a maximum at the long side of said core to a minimum at the short side thereof, including means for rotating said core about the longitudinal axis thereof, a wire feed carriage, means for moving said carriage along a path parallel to the axis of rotation of said core at a speed proportional to the rotational speed of said core about said axis, wire guide means mounted on said carriage, and means for oscillating the wire guide means relative to said carriage as said carriage moves along said core adjacent said bevel end thereof to vary the spacing between adjacent wire wraps, the improvement wherein the means for oscillating said wire guide means comprises:

a. a linkage system including a feed link carried by said wire feed carriage,

b. means mounting said wire guide means on said feedlink, and r c. means for oscillating saidfeed link with said guide means moving parallel to said rotational axis of said core.

2. The apparatus of claim 1 wherein:

a. said linkage system is a pantograph and said wire feed link is one link thereof.

3. The apparatus of claim 2 wherein said pantograph further comprises:

a. a guide link,

b. a spacer link,

c. means pivotally mounting said guide and spacer links on said carriage for pivotal movement about a pivot point fixed with respect to said carriage,

d. a drive link pivotally attached to said spacer link at a point thereon spaced from the pivotal connection of said spacer link to said carriage,

e. means pivotally attaching said wire feed link to said guide link at a point thereon spaced from the pivotal connection of said guide link to said carriage, and

f. means pivotally attaching said drive link to said feed link at a point intermediate the pivotal attachment of said guide link thereto and said wire guide means.

4. The apparatus of claim 3 wherein said oscillating means comprises:

a. means engaging said drive link at a point thereon intermediate the points of pivotal attachment thereof to said spacer link and feed link.

5. The apparatus of claim 4 further comprising:

' a. means for restraining said point on said drive link against movement in directions other than parallel to said core axis.

6.The apparatus of claim 5 wherein:

a. said point on said drive link lies substantially on a straight line connecting said pivot point fixed with respect to said carriage and said guide means.

7. The apparatus of claim 4 wherein said means engaging said drive link comprises:

a. a double acting piston and cylinder,

b. a piston rod attached to said piston and projecting from said cylinder, and

c. means interconnecting said piston rod and said drive link at said point thereon.

8. In apparatus for wrapping prestressing wire about a bevel pipe core including means for rotating a core about its axis and a carriage movable along a path parallel to said axis the improvement comprising:

a. a supporting framework mounted on said carriage,

b. a double acting piston and cylinder including a piston rod attached to said piston and projecting outwardly of said cylinder mounted on said framework,

c. a source of fluid under pressure,

d. means for directing said fluid into said cylinder on opposite sides of said piston,

e. means for controlling said fluid directing means in response to the desired spacing of wire wraps on said core,

' f. a drive link pivotally attached intermediate its ends to an outwardly projecting end of said piston rod,

g. track means mounted on said framework and extending parallel to said axis of rotation of said core,

h. means attached to said drive link at said point of attachment thereof to said piston rod and movable along said track means only in a direction parallel to the axis of rotation of said core,

i. a spacer link pivotally attached at one end to said supporting framework and at an opposite end thereof to one end of said drive link,

j. a guide link pivotally attached at one end thereof to said supporting framework at the point of attachment of said spacer link to said framework,

k. a feed link pivotally attached at one end to an end of said guide link opposite said one end thereof,

1. means pivotally attaching said feed link intermediate its ends to an end of said drive link opposite said one end thereof, and

m. guide means mounted on an end of said feed link opposite said one end thereof. =i

Claims

1. In apparatus for wrapping prestressing wire about a bevel pipe core with the spacing between adjacent wire wraps at the bevel end of said core varying from a maximum at the long side of said core to a minimum at the short side thereof, including means for rotating said core about the longitudinal axis thereof, a wire feed carriage, means for moving said carriage along a path parallel to the axis of rotation of said core at a speed proportional to the rotational speed of said core about said axis, wire guide means mounted on said carriage, and means for oscillating the wire guide means relative to said carriage as said carriage moves along said core adjacent said bevel end thereof to vary the spacing between adjacent wire wraps, the improvement wherein the means for oscillating said wire guide means comprises: a. a linkage system including a feed link carried by said wire feed carriage, b. means mounting said wire guide means on said feed link, and c. means for oscillating said feed link with said guide means moving parallel to said rotational axis of said core.

2. The apparatus of claim 1 wherein: a. said linkage system is a pantograph and said wire feed link is one link thereof.

3. The apparatus of claim 2 wherein said pantograph further comprises: a. a guide link, b. a spacer link, c. meaNs pivotally mounting said guide and spacer links on said carriage for pivotal movement about a pivot point fixed with respect to said carriage, d. a drive link pivotally attached to said spacer link at a point thereon spaced from the pivotal connection of said spacer link to said carriage, e. means pivotally attaching said wire feed link to said guide link at a point thereon spaced from the pivotal connection of said guide link to said carriage, and f. means pivotally attaching said drive link to said feed link at a point intermediate the pivotal attachment of said guide link thereto and said wire guide means.

4. The apparatus of claim 3 wherein said oscillating means comprises: a. means engaging said drive link at a point thereon intermediate the points of pivotal attachment thereof to said spacer link and feed link.

5. The apparatus of claim 4 further comprising: a. means for restraining said point on said drive link against movement in directions other than parallel to said core axis.

6. The apparatus of claim 5 wherein: a. said point on said drive link lies substantially on a straight line connecting said pivot point fixed with respect to said carriage and said guide means.

7. The apparatus of claim 4 wherein said means engaging said drive link comprises: a. a double acting piston and cylinder, b. a piston rod attached to said piston and projecting from said cylinder, and c. means interconnecting said piston rod and said drive link at said point thereon.

8. In apparatus for wrapping prestressing wire about a bevel pipe core including means for rotating a core about its axis and a carriage movable along a path parallel to said axis the improvement comprising: a. a supporting framework mounted on said carriage, b. a double acting piston and cylinder including a piston rod attached to said piston and projecting outwardly of said cylinder mounted on said framework, c. a source of fluid under pressure, d. means for directing said fluid into said cylinder on opposite sides of said piston, e. means for controlling said fluid directing means in response to the desired spacing of wire wraps on said core, f. a drive link pivotally attached intermediate its ends to an outwardly projecting end of said piston rod, g. track means mounted on said framework and extending parallel to said axis of rotation of said core, h. means attached to said drive link at said point of attachment thereof to said piston rod and movable along said track means only in a direction parallel to the axis of rotation of said core, i. a spacer link pivotally attached at one end to said supporting framework and at an opposite end thereof to one end of said drive link, j. a guide link pivotally attached at one end thereof to said supporting framework at the point of attachment of said spacer link to said framework, k. a feed link pivotally attached at one end to an end of said guide link opposite said one end thereof, l. means pivotally attaching said feed link intermediate its ends to an end of said drive link opposite said one end thereof, and m. guide means mounted on an end of said feed link opposite said one end thereof.