US3785759A

US3785759A - Machine for forming a continuous seamless concrete pipe

Info

Publication number: US3785759A
Application number: US00220258A
Authority: US
Inventors: R Midthun; B Johnson
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-01-24
Filing date: 1972-01-24
Publication date: 1974-01-15
Anticipated expiration: 1991-01-15

Abstract

A continuous seamless pipe is formed in a trench from a cementitious mix by advancing through the trench a carriage mounting a trailing cylindrical drum with its axis parallel to the direction line of carriage movement and a diameter equal to the internal pipe diameter, and a cylindrical skirt having a diameter approximating the outer pipe diameter concentrically surrounding the drum to define an intervening rearwardly opening annular cylindrical containing an annular piston. The cementitious mix is fed into the front end of the cylinder and the piston is driven rearwardly through the cylinder to extrude the mix through the open rear end of the cylinder to form the pipe wall and exert a forward reaction force on the carriage for propelling the latter through the trench. The plunger may be segmented to obtain more uniform extrusion about the full cylinder circumference. The drum may be driven in rotary or other motion, and the drum, plunger and/or skirt may be vibrated to compact the extruding mix. A rotary trowel on the rear end of the drum smooths the inner surface of the extruded pipe. The preferred cementitious mix is a low slump concrete which may be extruded to form a seamless concrete pipe without the need to internally support the pipe.

Description

United States Patent [191 Johnson et al.

[ MACHINE FOR FORMING A CONTINUOUS SEAMLESS CONCRETE PIPE [22] Filed: Jan. 24, 1972 [21] Appl. No.: 220,258

[52] US. Cl. 4125/59, 425/64 [51] Int. Cl K103i 3/06 [58] Field of Search 425/59, 63, 64, 62; 264/32, 33

[56] References Cited UNITED STATES PATENTS 2,734,248 2/1956 Gaudin 425/64 X 2,406,025 8/1946 Moor 425/59 3,530,552 9/1970 Calder 425/62 2,520,199 8/1950 Butcher 425/59 3,193,901 7/1965 Lee et a].., 425/59 3,363,524 l/l968 Cutenacci.... 94/46 3,562,056 2/1971 Olson 264/33 X 3,534,449 10/1970 Bllxt et al. 425/62 Primary ExaminerRobert D. Baldwin Assistant ExaminerJohn McQuade Attorney-Boniard I. Brown [451 Jan. 15,1974

[57] v ABSTRACT A continuous seamless pipe is formed in a trench from a cementitious mix by advancing through the trench a carriage mounting a trailing cylindrical drum with its I axis parallel to the direction line of carriage movement and a diameter equal to the internal pipe diameter, and a cylindrical skirt having a diameter approximating the outer pipe diameter concentrically surrounding the drum to define an intervening rearwardly opening annular cylindrical containing an annular piston The cementitious mix is fed into the front end of the cylinder and the piston is driven rearwardly through the cylinder to extrude the mix through the open rear end of the cylinder to form the pipe wall and exert a forward reaction force on the carriage for propelling the latter through the trench. The plunger may be segmented to obtain more uniform extrusion about the full cylinder circumference. The drum may be driven in rotary or other motion, and the drum, plunger and/or skirt may be vibrated to compact the extruding mix. A rotary trowel on the rear end of the drum smooths the inner surface of the extruded pipe. The preferred cementitious mix is a low slump concrete which may be extruded to form a seamless concrete pipe without the vneed to internally support the pipe.

8 Claims, 7 Drawing Figures o o O /0/ o T o /0 1, a /4 /00-. Z0

f 1] :1 )1 I /0 l 75 7 5/;

PATENTEDJAN l 5|974 SHEET 2 BF 2 FIG. 4.

FIG. 3.

MACHINE FOR FORMING CONTINUOUS SEAMLESS CONCRETE IPEFE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to the art of pipe fabrication and more particularly to a novel method and machine for extruding a cementitious material to form a continuous seamless pipe in a trench.

2. Discussion of the Prior Art Subsurface pipe lines are used for a variety of purposes, such as irrigation, sewage disposal, flood control and others. At the present time, such pipes are commonly constructed by excavating a trench and placing within the trench precast concrete pipe sections which are joined end to end to form a pipe. This method of pipe construction is quite time-consuming and costly and becomes more so as the pipe diameter increases.

U.S. Pats. Nos. 2,731,698, 3,091,013 and 3,338,546 disclose an improved method of subsurface concrete pipe construction. This construction method involves the use of a pipe forming or extruding machine which moves forwardly through a trench and extrudes an annular ribbon of concrete or other cementitious mix to fonn a continuous seamless pipe behind the machine as the latter advances.

SUMMARY OF THE INVENTION The present invention provides an improved pipe forming machine of the general class described. The forming machine has a carriage movable forwardly through the trench which is to contain the pipe. At the rear of the machine is a cylindrical drum having its axis parallel to the direction line of carriage movement and a diameter equal to the internal diameter of the pipe. Concentrically surrounding the drum is a thin walled cylindrical skirt having a diameter approximating the outer diameter of the pipe. The drum and skirt define an intervening annular rearwardly opening cylinder about the drum.

Mounted on the carriage forwardly of the drum for reciprocating movement through the cylinder is an annular plunger. Actuator meanssuch as hydraulic ram means drive the plunger back and forth through the cylinder. Preferably, the plunger is divided into independently movable segme'nts'power'ed by separate hydraulic cams. Between the plunger and the drum is a reservoir for containing a cementitious mix which is fed to the reservoir through a hopper. On the rear end of the drum is a rotary troweling device. The preferred cementitious mix is a semi-dry relatively low slump concrete mix, such as medium aggregate, sand, cement and selected admixtures. The invention will be described in connection with the use of such a concrete mix in the pipe forming machine. As will appear from the later description, however, other cementitious mixes may be used in the machine consisting of any suitable aggregate and binder.

In operation, the pipe forming machine is propelled slowly through the trench while it receives concrete mix through its hopper from a supply vehicle which moves along the trench machine. The annular plunger of the machine is driven in a reciprocating stroke through the annular cylinder about the machine drum. During each rearward stroke, the plunger displaces concrete mix from the reservoir into the cylinder as well as through openings in the skirt and finally extrudes the concrete through the rear open end of the cylinder to form a generally cylindrical pipe wall. The plunger then retracts forwardly to effect entry of more concrete mix into the cylinder, after which the plunger is again driven rearwardly through the cylinder to extrude an additional length of pipe.

The plunger is driven rearwardly with substantial force to extrude and compact the concrete mix to form a virtually self-sustaining pipe wall. This force produces a forward reaction force on the machine carriage which aids in propelling the carriage forwardly through the trench. An additional propulsion means, such as a winch, is provided for supplementing the reaction force produced by the plunger.

The drum of the machine supports the pipe wall internally as it is formed and smooths the inner wall surface as the drum moves forwardly. Additional smoothing of the inner wall surface, if necessary, may be accomplished by the rotating trowel at the rear of the drum. A primary feature of the invention resides in the use of a low slump concrete mix in the present machine. This low slump concrete enables extrusion of a seamless concrete pipe without the necessity 'of supporting the pipe internally until the concrete sets. According to another important feature of the invention, the drum, skirt and extrusion plunger mount vibrators for compacting the concrete mix as it is extruded so as to enhance the self-sustaining ability of the pipe wall.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a top view of a pipe forming machine according to the invention;

FIG. 2 is a longitudinal section through the machine;

FIG. 3 is a section taken on line 3-3 in FIG. 2;

FIG..4'is a section taken on line 44 in FIG. 2;

FIG. 5 is a section taken on line 5-5 in FIG. 2;

FIG. 6 is a side elevation of the shield of the machine; and

PEG. 7 is a section through a pipe extruded by the machine.

DESCRIITION OF THE PREFERRED EMBODIMENT The pipe forming machine 10 selected for illustration in the drawings has a carriage 12 which is movable forwardly in the direction of the arrow in FIG. 2 through a trench M. The trench has generally vertical side walls 116 and a rounded bottom wall 18. Machine carriage 112 has front and

rear sections

20 and 22 which can pivot laterally relative to one another,as explained below, to facilitate movement of the carriage around a curve.

Front carriage section 22 has a frame 24 with upstanding side walls 26 and a rounded bottom wall 28, constructed of boiler plate of the like. The frame is shaped and dimensioned in transverse cross-section to conform approximately to the cross-section of the trench M. Mounted on the bottom wall 23 is a platform 30 supporting a motor generator set or prime mover 32, in this instance an internal combustion engine. Engine 32 drives a winch 36 through a transmission 33. As will be explained presently, the winch 36 is utilized to move the pipe forming machine forwardly through the trench M by attaching the winch cable 39 to an anchor located some distance ahead of the machine.

The rear carriage section 20 has a frame 50 constructed of boiler plate or the like in a manner similar to the front carriage section. The front end of the rear section has a cross-section similar to that of the front section including a rounded bottom wall 42 and upstanding side walls 43. The remaining rear portion of the frame forms a cylindrical skirt 44 whose bottom portion is a continuation of the bottom frame wall 42 and whose axis coincides with the axis of curvature of the latter wall and the bottom wall 28 of the front carriage section 22.

The front end of the rear carriage section fits within the rear end of the front carriage section 22 so as to overlap the latter section a small amount. The front end of the rear section is sized to provide a small clearance between the overlapping

side walls

26, 43 of the sections. The overlapping

bottom walls

28, 42 of the sections are joined by a pivot 45. This pivot permits the two carriage sections to pivot laterally relative to one another through a small angle such that the pipe forming machine may travel around curves in the trench 14. The pivot is arranged to permit uncoupling of the two carriage sections for ease of transportation from one job site to another.

Extending across the front end of the rear carriage section 20 and welded or otherwise rigidly joined to the bottom and

side frame walls

42, 43 of the section are spaced

parallel frame walls

46, 48. A hollow cylinder is welded or otherwise rigidly joined to the rear side of the rear wall 48. Cylinder 50 has a cylindrical wall 52 and end

walls

54, 56. Mounted in the

walls

46, 48, 54, 56 are shaft bearings 58. Cylinder 50 and bearings 58 are aligned on the axis of the rear cylindrical skirt 44 of the rear carriage section 20.

Rotatably supported in the bearings 58 is a hollow shaft 60. Shaft 60 extends forwardly of the front frame wall 46 into the front carriage section 22 and rear wardly of the rear cylinder end wall 56 through the cylindrical skirt 44 along the axis of the skirt. The front end of shaft 60 is driven from the engine 32 through a speed reducer and clutch mechanism 62 and a belt or chain drive 64. Extending centrally through and rotatably supported in the shaft 60 is an inner shaft 66. The front end of shaft 66 is driven from the engine 32 through a speed reducer and clutch mechanism 68 and a belt or chain drive 70. It is significant to note here that the belts or chains of the

drives

64, 70 may be removed to permit uncoupling of the

carriage sections

20, 22.

Fixed on the rear end of the outer shaft 60 is a hollow cylindrical drum 72, the rear end of which projects a short distance beyond the rear end of the skirt 44. Drum 72 has a cylindrical wall 74, a somewhat domeshaped front end wall 76 and a flatter rear end wall 78. As shown most clearly in FIG. 2, the annular juncture 80 of the

drum walls

74, 76 is rounded. The annular juncture of the

drum walls

74, 78 is also rounded, though to a smaller radius. Cylinder 50 and drum 72 have the same diameter which is the internal diameter of the pipe to be formed. Fixed on the rear end of the inner shaft 66 is a rotary trowel 81 of the same diameter as the drum 72.

The skirt 44 of the rear carriage section 20 surrounds the cylinder 50 and drum 72 concentrically and has a diameter approximating the outer pipe diameter. The skirt and cylinder define an intervening annular cylinder 82. The skirt and drum define an intervening annular cylinder 84. Between the cylinder 50 and drum 72 is a space 86 providing a reservoir. A hopper 88 rises from the top of the skirt 44 over the reservoir and opens downwardly to the reservoir. The front end of the drum 72 mounts paddles 90 which project forwardly into the reservoir. In the sides of the skirt 44 are ports 92 which open to the reservoir. The rear end of the skirt is cut away at 94.

Movable through the

annular cylinders

82, 84 is an annular plunger 96. This piston has an axial length approximating the length of the cylinder 82. Actuator means 98, in this instance hydraulic or pneumatic ram means, are connected to the plunger for moving the latter back and forth through the cylinders. The plunger is movable between a forward retracted position in the cylinder 82 and a rearward extended position within the rear end of cylinder 84. During its movement between these positions, the plunger travels through the reservoir 86.

According to a feature of the invention the plunger 96 is divided into four independently movable segments 96a. The actuator means 98 comprise separate hydraulic rams 98a for driving the plunger segments back and forth. According to another feature of the invention, the drum 72, skirt 44 and plunger 96 mount vibration generators 100 for vibrating these parts.

Mounted atop the rear end of the skirt 44 is an operators station 101. This station is equipped with controls for engine 32, winch 36, clutch mechanisms 62, 68 and rams 98a.

In operation of the pipe forming machine, the winch cable 39 is anchored some distance ahead of the machine. The rams 98a are actuated to retract the plunger 96. The reservoir 86 is filled with a semi-dry relatively low slump concrete mix through the hopper 88. This concrete mix may be supplied to the machine by a concrete transport vehicle which moves along the side of the trench with the pipe forming machine. A system of baffles which are apparent in FIG. 1 and FIG. 5 are placed in the hopper to direct more concrete mix to the sides of the reservoir rather than down the center of the hopper. A major portion of the concrete thus feeds to the ports 92 through which the concrete passes to the outride of the skirt, and to the paddles 90. This action aids materially in getting the concrete quickly and efficiently into the intervening space between the outer skirt and the trench walls.

After the machine has been thus readied for operation, the winch 38 is operated to wind the cable 39 on the winch drum and thereby advance the machine slowly through the trench 14. The drum 72 and trowel 81 are driven in rotation. Rotation of the drum drives the drum paddles 90 about the reservoir 86 to constantly mix and agitate the concrete mix in the reservoir to prevent the mix from setting. This paddle rotation also displaces concrete mix from the reservoir through the skirt ports 92 into the region between the skirt 44 and the trench wall.

Actual extrusion of the concrete mix to form a pipe P is accomplished by operating the rams 98a to reciprocate annular plunger 96 between its retracted and extended positions. During each rearward stroke of the plunger, the latter displaces concrete mix from the reservoir 86 outwardly through the skirt ports 92 into the region between the skirt 44 and the trench wall and rearwardly through the cylinder 84 until the plunger enters over the rounded forward end of drum 72. As the plunger enters over the drum, the annular clearance space between the plunger and drum gradually closes by virtue of the rounded annular end wall portion 80 of the drum. As this clearance space closes, the plunger closes to displace concrete mix through the skirt ports 92 and continues to displace concrete mix, under increased force or pressure, rearwardly through the cylinder 8d. The concrete mix is extruded through the rear open end of the cylinder 84 to form the pipe P.

During this final portion of its extension or extrusion stroke, the plunger 96 imposes a relatively high force or pressure on the extruding concrete mix which compacts the mix. Additional compaction of the extruding concrete mix is accomplished by rotation of the drum 72 and by the vibrating action of the vibration generators 100. This compaction of the mix coupled with its semi-dry low slump characteristics results in an extruded concrete pipe P which is self-supporting and eliminates the need for internal supports within the pipe. In addition to extruding and compacting the concrete mix, the high force exerted by the plunger against the extruded pipe wall produces an opposite reaction force on the pipe forming machine. This reaction force aids the winch 36 in moving the machine forwardly through the trench 114.

When the plunger 96 reaches the end of its rearward extrusion stroke, it is retracted to the forward end of its travel, after which the cycle is repeated. Thus, the Pipe P is effectively extruded in successive but continuous sections during successive rearward extension strokes of the plunger. If necessary, the rate of forward travel of the machine through the trench 14 may be slowed or terminated during the forward'retract-ion or return strokes of the plunger to avoid the formation of discontinuities or weak spots in the pipe wall.

A feature of the invention resides in the fact that the rotating drum paddles 9:0 and annular plunger 96 cooperate to effect uniform distribution of the concrete mix about the full circumference of the annular cylinder 34. The plunger segments 96a may be extended in unison or independently, as required to obtain uniform extrusion of and pressure on the pipe wall about the full pipe circumference.

As the pipe forming machine advances, extruding the pipe P behind it, the inner pipe surface is smoothed by the rotating drum 72 and trowel 81. In this regard, it should be noted that the drum may be driven in other than a rotary motion, such as an oscillating or reciprocating motion or, for that matter, the drum may remain stationary. If desirable or necessary, the machine may be equipped with means for spraying water on the inner pipe surface to enhance this smoothing action.

A major advantage of the present pipe extruding machine resides in the fact that it produces a seamless pipe with a predetermined minimum wall thickness and a smooth walled bore having a high degree of roundness. As noted earlier, the preferred concrete mix for use in the machine is a low slump concrete which permits extrusion of a pipe without the necessity of internally supporting the pipe wall until the concrete sets. Other cementitious materials than concrete may be used, however.

What is claimed is:

l. A machine for forming a continuous seamless cementitious pipe within a trench, comprising:

a carriage movable forwardly through said trench,

a cylindrical drum at the rear of said carriage having its axis parallel to the direction line of carriage movement,

said drum having a diameter approximating the internal diameter of said pipe and a cylindrical length which is a major portion of the overall length of the drum means for driving said drum in a motion which does not alter the position of the drum axis relative to said carriage,

a cylindrical skirt about and concentric with said drum and having a diameter approximating the outer diameter of said pipe,

said drum and skirt defining an intervening rearwardly opening annular cylinder about the drum having a radial dimension approximating the wall thickness of said pipe,

means for feeding a cementitious mix into the forward end of said cylinder, and

means for feeding said mix rearwardly through and extruding the mix through the rear end of said cylinder during said motion of said drum to form the pipe wall between the drum and the trench walls as the machine moves forwardly through said trench, said feeding means comprising annular plunger means movable axially through and having a radial dimension approximating that of said cylinder, and fluid power actuator means connected between said carriage and plunger means for driving said plunger means back and forth through said cylinder.

2. A pipe forming machine according to claim 1 including:

vibrator means for vibrating said skirt.

3. A pipe forming machine according to claim 1 wherein:

said skirt has openings at the forward end of said drum through which said cementitious mix may flow to the exterior of the skirt.

4. A pipe forming machine according to claim l wherein:

said plunger means comprises a number of independently movable segments, and

said actuator means comprises independent actuators for driving said plunger segments independently through said cylinder.

5. A pipe forming machine according to claim 1 including:

paddles on the front end of said drum which rotates with said drum to agitate said mix entering the forward end of said cylinder and distribute the mix uniformly about said cylinder.

6. A pipe forming machine according to claim 1 wherein:

said carriage includes a rear section mounting said drum, skirt, plunger means and actuator means, and a front section,

means on said front section for driving said carriage through said trench, and

pivotal coupling means joining said carriage sections for relative lateral pivoting of said sections.

7. A pipe forming machine according to claim 6 wherein:

said coupling means are disengageable to permit separation of said carriage sections.

8. A pipe forming machine according to claim 11 including:

means for driving said drum in rotation,

a rotary trowel concentrically mounted at the rear end of and having the same outer diameter as said drum, and

means for driving said trowel in rotation independently of said drum motion.

Claims

1. A machine for forming a continuous seamless cementitious pipe within a trench, comprising: a carriage movable forwardly through said trench, a cylindrical drum at the rear of said carriage having its axis parallel to the direction line of carriage movement, said drum having a diameter approximating the internal diameter of said pipe and a cylindrical length which is a major portion of the overall length of the drum means for driving said drum in a motion which does not alter the position of the drum axis relative to said carriage, a cylindrical skirt about and concentric with said drum and having a diameter approximating the outer diameter of said pipe, said drum and skirt defining an intervening rearwardly opening annular cylinder about the drum having a radial dimension approximating the wall thickness of said pipe, means for feeding a cementitious mix into the forward end of said cylinder, and means for feeding said mix rearwardly through and extruding the mix through the rear end of said cylinder during said motion of said drum to form the pipe wall between the drum and the trench walls as the machine moves forwardly through said trench, said feeding means comprising annular plunger means movable axially through and having a radial dimension approximating that of said cylinder, and fluid power actuator means connected between said carriage and plunger meaNs for driving said plunger means back and forth through said cylinder.

2. A pipe forming machine according to claim 1 including: vibrator means for vibrating said skirt.

3. A pipe forming machine according to claim 1 wherein: said skirt has openings at the forward end of said drum through which said cementitious mix may flow to the exterior of the skirt.

4. A pipe forming machine according to claim 1 wherein: said plunger means comprises a number of independently movable segments, and said actuator means comprises independent actuators for driving said plunger segments independently through said cylinder.

5. A pipe forming machine according to claim 1 including: paddles on the front end of said drum which rotates with said drum to agitate said mix entering the forward end of said cylinder and distribute the mix uniformly about said cylinder.

6. A pipe forming machine according to claim 1 wherein: said carriage includes a rear section mounting said drum, skirt, plunger means and actuator means, and a front section, means on said front section for driving said carriage through said trench, and pivotal coupling means joining said carriage sections for relative lateral pivoting of said sections.

7. A pipe forming machine according to claim 6 wherein: said coupling means are disengageable to permit separation of said carriage sections.

8. A pipe forming machine according to claim 1 including: means for driving said drum in rotation, a rotary trowel concentrically mounted at the rear end of and having the same outer diameter as said drum, and means for driving said trowel in rotation independently of said drum motion.