US 3770219 A
Apparatus for forming a prestressing winding on a concrete pipe. The pipe is supported and rotated and the wire is fed to it so that it is wound onto the pipe. Before passing onto the pipe the wire passes around a rotatable drum which is rotated such that tension is maintained in the wire being fed onto the pipe. A differential coupling connected between the rotatable drum and the means supporting the pipe for rotation. A variable braking means is comprised of an electromagnetic coupling and a motor which act upon a rotatable planet carrier of the differential coupling. The braking establishes a torque in the coupling that resists rotation of the drum. The resulting torque reaction between the drum and the gear train is transferred to the means that supports and rotates the pipe. Inasmuch as tension of the wire is caused, the resisting torque of the gear train a control of the resisting torque will insure constant tension on the wire regardless of the rate of wire take-off.
Claims available in
Description (OCR text may contain errors)
United States Patent 1 Hickman Nov. 6, 1973 i 1 WINDING MACHINE  lnventor: Malcolm Douglas Hickman,
Dandenong, Australia  Assignee: Rocla Concrete Pipes Limited,
Princes Gate, Melbourne, Australia  Filed: Sept. 1, 1971 [.21] Appl. No.: 177,075
 U.S. Cl. 242/7.22 [51 l Int. Cl ..B2lf 17/00, B65h 77/00,
' B65h 81/08  Field ofSearch ..242/7-.22, 7.2l,7.23,
 Rum-mes Cited 7 UNITED STATES PATENTS 1 2,573,793 11/1951 Kennison 242/722 3,379,385 4/1968 Osweiler.... 242/722 3,572,596 3/1971 Dykmans... 242/721 2,251,205 7/1971 Revel 242/722 3,666,189 5/1972 Dykmans 242/721 PECOEDEE Primary Examiner Billy Sv Taylor Att0rneyCushmian, Darby & Cushman 57 ABSTRACT Apparatus for forming a prestressing winding on a concrete pipe. The pipe is supported and rotated and the wire is fed to it so that it is wound onto the pipe. Before passing onto the pipe the wire passes around a rotatable drum which is rotated such that tension is maintained in the wire being fed onto the pipe. A differential coupling connected between the rotatable drum and the means supporting the pipe for rotation. A variable braking means is comprised of an electromagnetic coupling and a motor which act upon a rotatable planet carrier of the differential coupling. The braking establishes a torque in the coupling that resists rotation of thedrum. The resulting torque reaction between the I drum and the gear'train is transferred to the means that supports and rotates the pipe. lnasmuch as tension of the wire is caused, the resisting torque of the gear train a control of the resisting torque will insure constant 5 Claims 3Drawing Figures PAIENIEnuuv sma sum 2 or 2 5/ A94 A77 by WINDING MACHINE BACKGROUND OF THE INVENTION 1. Field of Invention This invention relates to concrete or like pipes. More particularly the invention is concerned with apparatus for forming pre-stressing windings on such pipes.
2. Description of Prior Art There are various known types of apparatus for applying helical windings to pipes in order to prestress them. Normally the pipe to be pre-stressed is rotated about its longitudinal axis and the re-stressing wire is fed to it by wire feeding means which maintains the wire under tension. The wire feeding means generally comprises a winding drum around which the wire is wrapped. The drum is of a diameter closely related to the diameter of the pipe being wound and the wire is wrapped around it in such manner as to prevent slipping of the wire thereon. In order to maintain the wire tension whilst accommodating a. elongation of the wire,
b. differences in pipe diameter between the spigot and socket ends of the pipe, and
c. movement of the point of application of the wire on the pipe, the winding drum must be driven at a slightly different and variable speed relative to that of the'pipe. Conventionally, this is achieved by providing two separate drives for the pipe and the winding drum. This, however, entails a duplication of drive facilities of similar horsepower, which, with large diameter pipes and high wire tensions is uneconomical. By the present invention such dupli- I cation of drive facilities is avoided.
SUMMARY OF THE INVENTION According to the invention there is provided apparatus for forming a pre-stressing winding on a concrete or like pipe, comprising rotatable pipe support means adapted to support the pipe for rotation about its longitudinal axis, drive meanscoupled to the pipe support means so as to be operable to rotate the pipe about said axis, and wire feed means to feed wire to the pipe as it is rotated by the drive means, said wire feed means comprising a rotatable drum with which the wire is engaged and which in operation of the apparatus is rotated by the wire such that tension is maintained in the wire being fed to the pipe, wherein coupling means is connected between the drive means and the drum, which coupling means is conditionable to permit variation in the ratio of the rotational speed of the drum to the rotational speed of the pipe so as to maintain substantially constant tension in the wire.
Preferably the apparatus further comprises, in combination with the rotatable drum, a device for maintaining the wire in engagement with the peripheral surface of the drum, said device comprising pressure rollers spaced circumferentially of said peripheral surface and forming nips therewith and means to apply radially inward forces to the pressure rollers.
In order that the invention may be more fully explained, one particular embodiment thereof will now be described in detail with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS In the drawings,
. coupling 36 is connected to the output shaft of a small geared motor 33 mounted on the machine frame.
DESCRIPTION OF SPECIFIC EMBODIMENT The concrete pipe to be wound is denoted generally as l and FIG. 1 shows only its socket end 2, a part of its main cylindrical portion 3 and a tapered portion 4 connecting the end with portion 3.
Pipe 1 is mounted by any convenient means such as internal chucks'(not shown) on a shaft 6 which is journalled in bearings (not shown) and which carries a main drive gear wheel 7. The gear wheel 7 meshes with a pinion 8 on the output shaft of a main drive motor 9. Thus pipe l can be rotated about its longitudinal axis by the action of motor 9 driving through pinion 8 and gear wheel 7.
A winding drum 1 l is fixed to a shaft 12 which carries a gear wheel 13 and an epicyclic gear train denoted generally as 14 forms a coupling between the gears 7 and 13 and therefore between the shafts 6 and 12. The
epicyclic gear train 14 is disposed on a lay shaft l6 mounted in a pair of journalled bearings 17. One end of shaft 16 carries a gear 18 which meshes with the gear wheel 7 so that shaft 16 drives the gear wheel 7. Shaft 16 also carries a ear 19 serving as a sun gear for the epicyclic gear train. This sun gear meshes with a set of planet gears 21 journalled on planet hub pins 22 fixed to a planet carrier wheel 23. The planet carrier wheel 23 is mounted by means of a pair of ball bearings 24 on the lay shaft 16.
A furter set of planet gears 26 are mounted on the planet hub pins 22 and are direct coupled to the planet gears 21. As shown in the drawing the planet gears 21 and 26 can in fact be formed integrally with one another. The planet gears 26 mesh with a sun gear 27 which is direct coupled with a gear 28 meshing with the gear 13 on drum shaft 12. As shown in the drawing the gears 27 and 28 can be formed in a single structure which is rotatably mounted on the lay shaft 16 by bearings 29. I I
The outer periphery of planet carrier wheel 23 is formed with sprocket teeth 31 engaging a chain 32 via which the wheel 23 is coupled through a small chain sprocket 34 to an electromagnet coupling 36. The electromagnetic coupling 36 is of the type which can be adjusted to permit slip and in which the slipping torque can be varied. More particularly it is a powder magnetic coupling in which the slipping torque is determined directly by the magnitude of a control current passed through external field windings of the coupling. The control current is governed by a simple potentiometer 51. Potentiometer 51 includes a slide wire 52 connected to a power supply 53 and a rotatable contact 54 to slide on wire 52 and so vary the control current passing to the coupling via leads 55. The reaction side of In use of the apparatus motor 33 serves to provide a reaction torque for the coupling 36 so that the motor and coupling together serve as a variable braking means to act on the planet carrier wheel 23 with a braking force determined by the slipping torque setting of the coupling. Motor 33 may be a simple constant speed electric motor. It should, of course, be of sufficient size to generate a torque reaction equal to the maximum slipping torque setting of the coupling. Once the apparatus has been brought to operational speed, the'effect of motor 33 is merely to provide a torque reaction for coupling 36 which is equivalent to the reaction which would be obtained if the reaction side of the coupling were connected directly to the machine frame. As will be explained below, however, the use of the motor 33 instead of a direct connection to the machine frame enables the wire to be initially pre-stressed before the winding operation is begun.
The'wire 37 to be wound onto the pipe 1 is firstly wrapped withseveral turns around the winding drum 11 and then passes to the pipe and is anchored to the socket end of the pipe at 41. As will be explained in detail below, drum 11 is fitted with a device to hold the turns of wire in proper engagement with its periphery.
Pulley 39 is mounted on a carriage 42 movable along a track 43 extending longitudinally of the pipe 1 and as the pipe 1 is rotated in the direction indicated by arrow 44 the carriage 42 is driven along the track 43 in the direction indicated by arrow 46 so that helical windings 47 of wire are applied to the pipe. The rotation of pipe 1 causes wire to be drawn from the drum l1 and the wire is tensioned because rotation of drum 11 is resisted by a resisting torque delivered by the epicyclic gear train and accurately controlled by the setting of the electromagnetic coupling 36.
The coupling provided by the epicyclic gear train is such that the drum is rotated against a resisting torque and the resulting torque reaction is taken from the gear train onto the main gear wheel 7, the direction of this torque reaction being such that it assists the torque of the main drive motor 9. The slipping torque setting of coupling 36 determines the torque resisting the rotation of drum 11, the tension of the wire 37 and the torque reaction on gear wheel 7.
Pulley 38 is mounted on a fixed part 48 of the machine frame via a load measuring cell 49 which provides a measure of the wiretension. Cell 49 may be of a conventional type providing an electrical output proportional to the load on the cell. It may have output leads connected to a load recorder 57. In one standard type of load cell suitable for the purpose a lead bearing element in the cell forms one leg of a Weatstone bridge circuit, an output current being generated according to the degree unbalance in the circuit caused by load on the element.
The arrangement is such that the torque resistance will be maintained constant regardless of variations in the speed at which wire is drawn from drum 11 due to variations in diameter of the pipe 1 and the travel of pulley 39, this torque being determined by the slipping torque setting of coupling 36. In this way the large torque reaction circulating within the closed drive system is accurately controlled by the relatively small braking force applied to the planet carrier wheel 23 by coupling 36 and motor 33.
This is the small brake motor 33 to provide the reaction force for the coupling 36 permitting the wire to be sion is maintained, the drum 11 then being rotated by the wire in the same direction but against the opposing torque built up through the epicyclic gear train.
As an indication of what gear ratios are appropriate,
details of the various gears used in the llustrated apparatus are as follows:
Gear 7 I teeth Gear 8 26 teeth Gear 18 26 teeth Gear 19 69 teeth Gears 21 l9 teeth Gears 22 16 teeth Gear 27 72 teeth Gear 28 40 teeth Gear 13 teeth The chain drive provides a 5:1 reduction between the planet carrier wheel 23 and the sprocket 34 and the epicyclic gear train provides a 1.23921 reduction between the shaft 16 and the gear 28. V
Motor 9 drives the pipe lat l l-% R.P.M. and the diameter of the winding drum 11 is approximately 0.63 times the diameter of the main cylindrical portion of the pipe.
The drive drum 11 and a device for maintaining the wire in contact with the drum are detailed in FIGS. 2 and 3. As seen in these figures, the drum 11 comprises a central web 124 and a rim 126 having side flanges 127 to either side of a peripheral surface 128. As can be seen in FIG. 3, the peripheral surface 128 of drum 11 is conically tapered to a slight extent. The angle of the taper is only about 8. The wire 37 is wrapped on the peripheralsurface 128 of the winding drum 11 through, say, seven turns 131. The wire is fed to the drum from a supply coil (not shown) via a guide tube 132. It extends onto the drum at the larger diameter end of the tapered surface 128 and leaves the drum from the smaller diameter end. V
The wire turns 131 on the drum 11 are engaged by two pairs of pressure rollers 133 mounted on roller carrier brackets 134. The latter brackets are pivotally connected at 136 to a pair of lever arms 137 which are pivotally connected by fulcrum pins to the machine frame 123. Fulcrum pins 138 are removable and they can be engaged with any of a number of holes 139 provided in the machine frame 123 whereby the positions of the lever fulcrums can be adjusted. Similarly a numberof holes 141 are provided in the levers 137 for adjustment purposes.
The ends 142 of levers 137 are interconnected by power applicator means 143 operable to draw those ends toward one another. The power applicator means 143 comprises a pneumatic power unit 144, the outer casing of which is connected to a long bar 146 connected by a pivot pin 147 to one of the levers 137, the pin 147 being engaged with one of a series of holes 148 in the bar 146. The thrust rod 149 of unit 144 carries a block 151 slidable in a slot 152 in the bar 146 and pivotally connected by a pin 153 to the end 142 of the other lever 137. The action of the power applicator means is to draw the ends 142 of the levers 137 toward one another so as to bias the roller carriages 64, and, therefore the rollers 133 inwardly of the drum 11. As shown in FIG. 3, each roller 133 engages only the wire turn 131 at the larger diameter end of the drum surface 128, i.e., the first turn of wire. The application of roller pressure of this first turn of wire results in a greater wire tension than would otherwise be achieved by the build-up of tension through the seven turns and also prevents the wire turns from riding-up by forcing the incoming wire down beside the preceding turn.
The tapered profile of the drum counteracts the tendency for the wire to track. As the wire gains tension through the turns 131 it tends to slip down the sloping surface 128 of the drum. The two tendencies counteract one another and tracking is thereby avoided. In order to prevent the turns of wire at the lower diameter end of the surface 128 from riding-up on the preceding turns on reversing the machine the peripheral surfaces of rollers 133 are also tapered slightly. The taper of the rollers 133 is, however, very slightly less than that of the drum surface so that there is a slight clearance between the rollers 133 and all of the turns of wire except the first turn at the larger diameter end of the drum. It is most desirable that only the first turn be gripped by the rollers 133 in order to allow proper build-up of tension through the successive wire turns 61. As the tension builds up in the wire turns, the wire extends so that there is a slight movement of the wire with respect to the drum surface 128, the extension increasing from zero at the position where the wire goes onto the drum to a maximum at the position where it comes off the drum.
The wire guide tube 132 may conveniently be mounted between a sleeve 154 on bar 146 and a lug 156 on the machine frame 123.
The illustrated apparatus can be varied to achieve even more accurate control over the wire tension. More particularly a control connection can be made between the load cell 49 and the potentiometer which sets the slipping torque of the electro-magnetic coupling 36. One suitable form of control connection is indicated by broken lines in FIG. 1. As indicated,.a pair of tapping leads are connected between the output leads 56 of the load cell and the potentiometer 51 governing the control current in the electro-magnetic coupling. Variations in the load cell output indicative of fluctuations in wire tension will condition the potentiometer so as to vary the control current of the electromagnetic coupling thereby to counteract the wire tension fluctuation. In this manner, a very accurate control over the wire tension is achieved.
1. Apparatus for forming a pre-stressing winding on a concrete or like pipe comprising:
rotatable pipe support means that supports the pipe for rotation about a longitudinal axis thereof; drive means to cause rotation of the support means and the pipe;
wire feed means to feed wire to the rotated pipe so as to be wound onto the pipe, said wire feed means comprising a rotatable wire tensioning drum with which the wire is engaged;
differential coupling means connected between the drum and the pipe support means, said coupling means comprising, a pair of coaxial sun gears coupled respectively to the drum and the'pipe support means, a planet gear carrier rotatable about the axis of the sun gears, and planet gear means mounted on said carrier and engaged with said sun gears; and
variable braking means acting on the rotatable planet carrier, said variable braking means comprising an electromagnetic coupling and a motor, the electromagnetic coupling being coupled between the planet gear carrier and the motor such that the motor is drivable so as to apply through the electromagnetic coupling to the planet carrier torque in a direction opposite to the direction of rotation of the planet carrier, whereby in operation of the apparatus the drum is rotated such that tension is maintained in the wire being fed to the pipe and said coupling means permit variation in the ratio .of the rotational speed of the drum to the rotational speed of the pipe so as to maintain the wire tension substantially constant at a value determined by the braking torque applied to the planet carrier through the electromagnetic coupling.
2. Apparatus as claimed in claim 1, which further includes wire tension measuring means to measure the tension of the wire being fed to the pipe and a control connection between the tension measuring means and 1 said electromagnetic'coupling such that the slip of said coupling is varied so as to reduce fluctuation in wire tension from the constant tension.
3. Apparatus for forming a pre-stressing winding on a concrete or like pipe comprising:
rotatable pipe support means that supports the pipe for rotation about a longitudinal axis thereof; drive means to cause rotation of the pipe support means and the pipe; wire feed means to feed wire to the rotated pipe so as to be wound onto the pipe, said wire feed means comprising a rotatable wire tensioning drum with which the wire is engaged; I coupling means connected between the drive means and the drum which is conditionable to permit variation in the ratio of the rotational speed of the drum to the rotational speed of the pipe while transmitting a substantially constant torque from the drum to the support means; and I wire holding means to hold the wire in contact with the peripheral surface of the drum, said holding means comprising a pair of lever arms, a pair of roller carriers mounted on the lever arms at opposite sides of the peripheral surface of the drum, pressure rollers mounted on the roller carriers so as to be spaced circumferentially of said peripheral surface and to form hips therewith, and actuator means to operate the lever arms so as to exert radially inward forces on the pressure rollers. 4. Apparatus as claimed in claim 3, wherein said peripheral surface of the drum is conically tapered and said pressure rollers are such that when a plurality of turns of wire are wrapped on said conically tapered peripheral surface of the drum, the pressure rollers can firmly engage only that turn of wire which is located toward the larger diameter end of the said tapered-surface.
5. Apparatus as claimedin claim 4, wherein the peripheral surface of each pressure roller is conically tapered to follow the taper of the peripheral surface of the drum but to a lesser extent so'as to firmly engage said one wire turn only.