US 3912181 A
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Unite States e Mullendore Oct. 14, 1975  METHOD AND APPARATUS FOR 3,614,005 10/1971 Chartier 242/722 WRAPPING A BEVEL PIPE CORE 3,666,189 5/1972 Dykmans 242/7.2l 3,734,421 5/1973 Karlson 242/721  Inventor: David L. Mullendore, Centerville,
 Assignee: Price Brothers Company, Dayton,
 Filed: Oct. 3, 1972  Appl. No.: 294,625
 US. Cl 242/7.02; 242/722  Int. Cl. BGSH 81/00  Field of Search 242/721, 7.22, 7.23, 7.02,
Primary Examiner-Billy S. Taylor Attorney, Agent, or FirmBiebel, French & Bugg [5 7] ABSTRACT Method and apparatus for automatically varying the spacing between adjacent wraps of prestressing wire in a concrete pipe core at the bevel end to accommodate the unequal length sides of the pipe core, in which the rotational position of the pipe core and the linear position of a wire feed carriage moving axially along the core are electronically monitored and signal generation proportional to both the rotational position of the References Cited pipe and the axial position of the carriage to control UNITED STATES PATENTS the oscillation of a wire guide mounted on the carriage 2,964,252 12/1960 Rosenberg 242 715 as the Carriage moves along the bevel end of the Core- 3,128,956 4 1964 Schumann 242/709 3,5 87,659 6 1971 Breitfuss et al. 242 702 X 4 6 nrwmg F'gures HYDRAULIC PUMP 44 22 l L SERVO hp AMPLIFIER Y K) PIPE SIZE 5 CONTROL 0 so 64 56 l 1 BEVEL LENGTH ANALbe To FLU/z w I "CONTROL mew/u. A g 1' N SELECT) CONVERTER s4 52 @1- Y I LINEARIZING SYNCRO ".135 BY F SJ NETWORK TRANSMITTER 1 svncno SYNCRO T0 MUL J DIFFERENTIAL SINE/COS DIGITAIT T Z XP J AEOG TRANsmTTER, CONVERTER CONVERTER QR 2s 1 32 I Sheet 2 of3 3,912,181
Oct. 14, 1975 US. Patent US. Patent Oct. 14, 1975 Sheet 3 of3 3,912,181
FIG-4 METHOD AND APPARATUS FOR WRAPPING A BEVEL PIPE CORE 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 cases, however, particularly where it is desired to 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 one 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 36 inch full bevel pipe the longer side is three inches longer than the shorter side. In a half bevel pipe the long side of the pipe is inche 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 at the 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 judgement for obtaining the desired wire wrap spacing on the pipe. For example, US. Pat. No. 3,052,419 discloses cam controlled apparatus for wrapping bevel pipe. U.S. Pat. No. 3,052,266 is directed to the method of using such apparatus and the pipe produced thereby. Also of interest in this field in US. Pat. No. 3,587,659.
It will be apparent, however, that in view of the variations in pipe size which will be encountered in normal wrapping operations, and the fact that the pipe may have either a full or half bevel, it is desirable, not only to provide apparatus which automatically produces the correct wrap spacing variation, but also a system which is extremely flexible in adjusting to different pipe sizes and bevels. Obviously, where control of the wire wrapping mechanism is dependent upon a cam of fixed size, the flexibility of the apparatus in accommodating both pipes of different dimensions and pipe having different amounts of bevel will be limited.
SUMMARY OF THE INVENTION The bevel wrap controller of the present invention provides a system for automatically wrapping bevel pipe of a variety of sizes having either a full or half bevel.
The controller in accordance with the present invention produces a bevel wrap having a uniform pitch along the long side of the pipe, less than the normal pitch at all other points around the pipe, and a minimum pitch on the short side thereof. This difference in pitch from the long side of the pipe to the short side is initially parallel to the bevel end of the pipe (during the first wrap) and gradually approaches a normal wrap with each revolution of the pipe.
The bevel wrap controller consists of an electronic signal synthesizer, a control panel, a synchro drive mechanism, an electro-hydraulic servo system, and a bevel wire control mechanism.
The electronic signal synthesizer converts signals from a synchro (angle) transmitter and from the operators control panel into suitable electrical control signals for the electro-hydraulic servo system. The synchro transmitter is coupled to the mechanism which causes the pipe to rotate, so that the synchro transmitter rotor makes one revolution for each revolution of the pipe. Thus, the output signal from the synchro transmitter is a continuous representation of pipe rotation. The operators control panel includes controls for setting pipe size and bevel length, as well as other controls required for initial set up.
The electro-hydraulic servo system includes a hydraulic pump which produces the power required by a hydraulic cylinder to deflect the wire from its normal position to that required to produce the bevel wrap. The servo system is controlled through an electrically operated servo valve. A linear displacement transducer (LVDT) coupled to the hydraulic cylinder gives a continuous electrical indication of the actual position of the cylinder. This signal is compared to the control signals from the signal synthesizer and the resultant error signal controls the servo valve.
Thus, with the bevel wrap controller of the present invention not only is the correct spacing between wire wraps necessary to accommodate the pipe bevel automatically provided, but the present system also permits infinite adjustability to accommodate variations in pipe size and bevel.
Other objects and advantages of the invention will be apparent in the following description, the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF 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 mechanism;
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. 1 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 as 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. The syncro 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 syncro 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 431-3-B-60 -l 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 coverter (e.g., the cosine output) is applied to a summing amplifier 32 where it 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-l l- 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, lnc., type 408). The output of the servo amplifier 42 controls a servo value 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 10 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 1/10 or l/20. A gain of one tenth corresponds to a full bevel position of switch 54 while a gain of 1/20 corresponds to a half bevel position of the switch. Amplifier 52 is connected to an analogue to digital converter 56 (Datel, type ADC-E 12B which continuously converts the analogue imput 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 1 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 determined 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 112 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. Journalled 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 of the like 138. Outwardly of the knuckle 136 the shaft is journalled, 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 noted above, the flow 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 cylinder. 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 feek 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 supporting 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 are, as would be the case if a pivotally mounted arm were utilized.
From the above construction, it will be seen that the present invention provides 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 moves substantially parallel to the axis of the pipe.
While the methods and forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise methods and forms of apparatus, and that changes may be made therein without departing from the scope of the invention.
What is claimed is:
1. In apparatus for wrapping prestressing wire about a pipe core having a bevel portion adjacent one end thereof, including means for rotating a bevel pipe core about its longitudinal axis, a wire feed carriage, means for moving said carriage along a path parallel to the longitudinal axis of said pipe, wire guide means mounted on said carriage to direct wire onto said pipe, and means for oscillating said wire guide means as said carriage moves along said pipe adjacent said bevel portion thereof, the improvement comprising:
a. means for generating an electrical signal of sinusoidal waveform which is correlated with the rotation of said pipe about its axis,
b. means for modifying said sinusoidal signal in accordance with the diameter of the pipe being wrapped by adding thereto an offset voltage,
c. means for generating an electrical signal in accordance with movement of said wire feed carriage,
d. means for further modifying said sinusoidal waveform signal to reduce its amplitude as the bevel portion of said pipe is wrapped, and
e. means responsive to said further modified sinusoidal signal for controlling the oscillation of said wire guide means.
2. The apparatus of claim 1 further including:
. means for adjusting the phase of said sinusoidal wave form signal with respect to the initial position of the bevel pipe core.
3. The apparatus of claim 1 wherein:
. said means for generating electrical signals representing the movement of said wire feed carriage includes means for generating a predetermined number of pulses for each increment of movement of said carriage, and
b. said means for further modifying said sinusoidal signals includes a digital to analogue converter responsive to said pulses to reduce the amplitude of said sinusoidal signal by specific increments in response to predetermined numbers of said pulses.
4. Method of wrapping wire on 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 of said core, said method including the steps of:
a. rotating said core about its longitudinal axis, feeding wire onto said core under tension while moving the wire feed parallel to the axis of rotation at a speed proportional to the rotational speed of said core thereby to establish the maximum spacing between wire wraps,
b. generating an electrical signal of sinusoidal waveform in response to the rotation of said core wherein one period of oscillation is generated for each revolution of the core,
c. modifying said sinusoidal signal in accordance with the diameter of the core being wrapped by adding thereto an offset voltage,
. generating a second electrical signal representing the position of the wire along the longitudinal axis of said core,
. further modifying said sinusoidal signal in response spacing on the long side of said core.