US2840880A

US2840880A - Process for casting concrete pipe

Info

Publication number: US2840880A
Application number: US413754A
Authority: US
Inventors: Jessen George Ronald; Chanlund Carl Wilmer
Original assignee: Cen-Vi-Ro Pipe Corp
Current assignee: Cen-Vi-Ro Pipe Corp
Priority date: 1954-03-03
Filing date: 1954-03-03
Publication date: 1958-07-01
Anticipated expiration: 1975-07-01

Description

July 1, 1958 e. R. JESSEN ETAL 2,

PROCESS-FOR CASTING CONCRETE PIPE Filed March 5, 1954 2 Sheets-Sheet 1 INVENTORS 6501955 2. MES-95V me: (a CH/ZULU/VD BY 01 W5 July 1, 1958 G. R. JESSEN EI'AL PROCESS FOR CASTING CONCRETE PIPE 2 Sheets-Sheet 2 INVENTORS 650965 ,e. JESSE/(I 00a m CH4NLU/VD BY fif'fOEA/EVS Filed March 3, 1954 PROCESS FOR CASTING CONCRETE PIPE George Ronald Jessen and Carl Wilmer Chanlund, Salt Lake City, Utah, assignors, by mesne assignments, to Cen-Vi-Ro Pipe Corporation, South Gate, Calif., a corporation of Delaware Application March 3, 1954, Serial No. 413,754 6 Claims. Cl. 25-155} This invention relates to the production of concrete pipe and the like, and has particular reference to a process for centrifugally casting concrete pipe of the type having bell and spigot joints.

In the manufacture of concrete pipe two basic types of joints are commonly used. These are the tongue and groove joint wherein the pipe sections are continuously cylindrical, and the so-called bell and spigot joint wherein cepted that, regardless of; the specific methodof manufacture, two elements are necessary, namely, a mold having a flared end, and a so-called forming ring attached to the flared end, the ring having an outer surface de signed to mold the inner mating surface of the pipe bell section. This mold and ringarrangement has not been entirely successful when used in centrifugal spinning processes utilizing a conventional Wet concrete mix. ,The primary reason for this is that the excess water which is removed during thespinning carries with it fines from the coricrete,.the flow of water and fines passing between the bell forming: ring and the concrete and, inso doing, Washing the mating surface of the bell. The finished mating surface. thus exhibits flow channels as well as a soft slurry surface. It is readily apparent thatfor pressure pipes, the accuracy and quality of the bell mating surface must be maintained at an optimum to avoid leakage, and it is further apparent that a washed and/orsoft surface is not satisfactory. One solution to this problem is to grind the bell section surface after casting of the wet mix, but this procedure is, of course-, economically prohibitive. The most widely accepted solution heretofore has emailed the use of steel joint. rings embedded in the pipe. This arrangement is also subject to inherent disadvantages in that the joints must be mortar-protected in an attempt to inhibit corrosion. of the steel rings, sometimes without complete success. One of the principalobjects of this invention is, therefore, to provide a method for casting concrete pipe of the bell and spigot joint type, which method is notsubjectto the inherent disadvantages of themethods heretofore pro posed and used. g

In our copending application; Serial No; 187,452 filed September 29, 1950, now Patent 2,671,260 granted March 9, 1954 entitled Method and Apparatus for Making Pipe From Concrete and Like Materials, is diseloseda method and apparatus for casting concrete pipe utilizing a snbstan'tially dry concrete mix, i; e;, a having a' relatively low cement-water ratio such as, for example; of the order of about 0.25. It has been found that, in addition to the advantages of such a mix, as outlined insaid copending application, a substantially dry concrete mix is highly suitable for use in making concrete pipe of the bell and spigot joint type, due in part to the fact that the run-off of excess water during the spinning of the mold is insufiicient to cause washing of the bell section mating surface. Another object of this invention is to provide a process for forming concrete pipe of the bell and spigot type utilizing a substantially dry concrete mix.

Yet another object of this invention is to provide a process for the production of concrete pipe of the bell and spigot type wherein a series of novel steps are utilized in producing the bell section of the pipe.

Other objects and advantages of this invention, it is believed, will be readily apparent from the following detailed description of a preferred embodiment thereof when read in connection with the accompanying drawings.

In the drawings:

Figure 1 is a front elevation of a centrifugal casting apparatus adapted to be used in carrying out the process of this invention.

Figure 2 is a vertical side sectional elevation of a portion of the apparatus.

Figure 3 is an enlarged fragmentary sectional view illustrating the bell section of the mold and finished P P Figure 4 is a side elevation, partially in section, illustrating the apparatus utilized in carrying out the process of i this invention.

h Figure S is a fragmentary perspective View illustrating the concrete delivery conveyor.

v Figure 6 is a vertical sectional elevation of the finished Referring now to the drawings, the centrifugal casting portion of the apparatus is of the type set forth in our said copending application, Serial No. 187,452. As shown best in Figures 1 and 2, the apparatus includes a frame 10 and a-mold 11 supported for rotation on two pairs of

trunnions

14 and 15. The trunnions, preferably of pneumatic construction, are mounted on suitable axles 16 driven through a transmission 18 by means of a motor 20. A roller compacting element 22 extends longitudinally through the mold 11, being rotatably supported on arms 24 at each end thereof. The arms are pivotally connected to the frame by means of a shaft 26 mounted insuitable bearings 27. Means are provided for raising and lowering the compacting roller and as shown in Figure 1, these means may include the power cylinder assemblies 29, the piston rods 30 of which are pivotally connected to the arms 24. Means are also provided for vibrating the mold at a high frequency and as shown, these means may include the high frequency vibrator element 35 adapted to be moved into contact with the outer Wall of the mold by means of its supporting arm 36 which is pivotally connected at a point intermediate the ends thereof to the shaft 26, the end of the arm remote from the vibrator element being pivotally connected to the piston rod 38 of a power cylinder assembly 40. I

As shown in Figure 4, the apparatus utilized in carrying out the process of this invention additionally comprises a concrete delivery mechanism generally indicated 50, including an endless conveyor 51 mounted on a carrier 53, the carrier being provided with flanged wheels 54 for movement on the tracks 55. A concrete mixing apparatus 56 may be suitably mounted on the carrier 53 and provided with a chute 58 for feeding concrete to the conveyor 51.

The conveyor 51 comprises an endless belt 60 extending between end rollers 62 and driven through a suitable transmission 64 by means of the motor 65. The rollers 62 are mounted in an I-beam member 65 which also carries support rollers 70 for the belt.

As shown in the drawings, the mold 11 is generally cylindrical and is provided at one end with a bell section. or flared, bell-forming portion 80 which conforms to the outer surface of the bell section of the pipe to be produced. A bell forming ring 82, preferably of steel, is provided, the ring having an annular end wall 82a, an intermediate cylindrical portion 82b, and an inner annular wall 820, thus being suitably shaped to form the inner and endsurfaces of the pipe bell section. Means are provided for securing the ring 84 to the mold, and as shown in the drawings, these means include the opposed annular grooves 83 and 84 in the ring and mold respectively, and a split snap ring 85 extending into both of these grooves. Similarly, a spigot forming ring 86 is secured to the spigot end 87 of the mold by means of the split snap ring 88 seated in annular grooves in the ring 86 and mold, respectively.

In carrying out the process of this invention, a cagelike steel reinforcing section (not shown) for the pipe in placed in the mold and the supporting trunnions 14 and are put into operation, causing the mold 11 to be rotated at a speed sufiicient only to maintain the concrete in place as it is poured in the manner described below. This speed is about 3040% of the maximum, or spinning speed, the maximum spinning speed being in the vicinity of 4500 ft./min., but varying widely depending upon pipe size. The vibrator element 35 is actuated to vibrate at a frequency of several thousand cycles per minute. With the concrete delivery mechanism 50 in the position shown in Figure 4, and with the mold rotating at the speed indicated, the conveyor 51 is then actuated to deliver the substantially dry concrete mix into the bell section of the mold. The mechanism 50 is maintained in the position shown until the concrete level is substantially above that of the forming ring. The mechanism 50 is then slowly withdrawn with continued delivery of substantially dry concrete, filling the remainder of the mold to form the barrel of the pipe.

When the mold is filled, the vibrator element is deenergized and the roller compacting element 22 is lowered to bear against the. cylindrical

rolling edges

90 and 91 of the forming

rings

82 and 84. This roller action forces the concrete, which was placed above the forming ring 82, downinto the bell section of the mold. More concrete is then added and forced into the bell section by the roller as needed until the mold will receive no more, the roller functioning both to compact the concrete by pressure and also as a screed to obtain the desired uniform inside pipe diameter.

The speed of the mold is then increased slightly, to 50-60% of the maximum spinning speed, and the vibrator element is again energized, with the roller 22 still in the compacting position, for a short interval to assure complete compaction and uniform inside diameter, and to relieve any tension existing in the reinforcing steel. After this simultaneous vibrating, spinning and compacting step, the roller is raised out of contact with the pipe, the vibrator element is de-energized, and the mold is "spun out at the maximum, or spininng speed to complete the pipe.

The completed pipe 100 is shown in Figure 6, having a generally cylindrical barrel section 101, a bell section 102 and a spigot end 103.

While a specific embodiment of this invention has been shown and described, it is not intended to limit the same to the exact details of the construction set forth, and it embraces such changes, modifications and equivalents of the parts and their formation and. arrangement as come within the purview of the appended claims.

We claim:

1. In a method of forming, from a substantially dry concrete mix, concrete pipe of the type having a bell end,the steps comprising spinning a hollow cylindrical mold having a bell-forming portion at one rate, introducing a substantially dry concrete mix into the mold, contacting a portion of the length of the mold progressively throughout the circumference during said spinning with a vibrator at a fixed location to impart high frequency vibrations to the mold to pack the concrete mix against the mold while the mold is being filled, applying positive pressure to the concrete mix to further pack the same against the mold while said mold is spinning and being vibrated, removing said positive pressure and said vibrator, and spinning said mold at a more rapid rate to impart additional centrifugal force to said concrete mix.

2. In a method of forming, from a substantially dry concrete mix, concrete pipe of the type having a bell end, the steps comprising spinning a hollow cylindrical mold having a bell-forming portion at one rate, introducing a substantially dry concrete mix into the mold by first introducing said mix into the bell-forming portion during said spinning to fill the same and then introducing said mix into the remainder of the mold progressively from the bell-forming portion to the end opposite thereto contacting at a location adjacent the bell-forming portion a portion of the length of the mold progressively throughout the circumference with a vibrator at a. fixed location to impart high frequency vibrations to the mold to pack the concrete mix against the mold while the mold is being filled and rotated, applying positive pressure to the concrete mix to further pack the same against the mold while said mold is spinning and being vibrated, removing said positive pressure and said vibrator, and spinning said mold at a more rapid rate to impart additional centrifugal force to said concrete mix.

3. In a method of forming, from a substantially dry concrete mix, concrete pipe of the type having a bell end, the steps comprising spinning a hollow cylindrical mold having a bell-forming portion at one rate, introducing a substantially dry concrete mix into the mold by first introducing said mix into the bell-forming portion to fill the same and then introducing said mix into the remainder of the mold, contacting progressively throughout the circumference a portion of the length of the mold with a vibrator at a fixed location to impart high frequency vibrations to the mold to pack the concrete mix against the mold while the mold is being filled, removing said vibrator, applying positive pressure to the concrete mix to further pack the same against the mold While said mold is spinning, again imparting high frequency vibrations to said mold progressively throughout the circumference while said mold is spinning and receiving the application of pressure, removing said positive pressure and said vibrator, and rapidly spinping said mold to impart additional centrifugal force to said concrete mix.

4. In a method of forming, from a substantially dry concrete mix, concrete pipe of the type having a bell end, the steps comprising spinning a hollow cylindrical mold having a flared, bell-forming end portion, introducing a substantially dry concrete mix into the mold by first introducing said mix into the bell-forming portion to fill the same to overflowing and then introducing said mix into the remainder of the mold progressively throughout the length and in quantity adapted to overfill the mold, applying positive pressure to the concrete mix to pack the same against the mold while said mold is spinning, removing said pressure, and increasing the speed of spinning of the mold to impart additional centrifugal force to said concrete mix.

5. In a method of forming, from a substantially dry concrete mix, concrete pipe of the type having a bell end, the steps comprising spinning at a selected rate a hollow cylindrical mold having a flared, bell-forming end portion, introducing a substantially dry concrete mix into the mold by first introducing said mix into the bellforming portion to fill the same and then introducing said mix into the remainder of the mold, applying to the mold progressively throughout the circumference high frequency vibrations throughout a given portion along the length of the mold to pack the concrete mix against the mold while the mold is being filled, removing said vibrations, applying positive pressure to the concrete mix to further pack the same against the mold While said mold is spinning, increasing the speed of spinning of the mold, again imparting high frequency vibrations to said mold progressively around the entire circumference While said mold is spinning and receiving theapplication of pres sure, removing said pressure and vibrations, and further increasing the speed of spinning of the mold to impart additional centrifugal force to said concrete mix.

6. In a method of forming, from a concrete mix, concrete pipe of the type having a bell end, the steps comprising spinning a hollow cylindrical mold having a flared, bell-forming end portion at a selected rate of about 30 40% of the maximum spinning rate, introducing a concrete mix into the mold by first introducing said mix into the bell-forming portion to fill the same and then introducing said mix into the remainder of the mold, applying high frequency vibrations to the mold at several thousand cycles per minute at a progressive location about the circumference and along a portion of the length of the mold so that the vibrations are progressively applied around the entire circumference of the mold to pack the concrete mix against the mold while the mold is being filled, removing said vibrations, applying positive pressure to the concrete mix to further pack the same against the mold While said mold is spinning, increasing the speed of spinning of the mold to a rate equal to about 60% of the maximum spinning rate, again imparting high frequency vibrations of several thousand cycles per second to said mold While said mold is spinning and receiving the application of pressure, re moving said pressure and vibrations, and further increasing the speed of spinning of the mold to full spinning speed of approximately 4500 feet per minute to impart additional centrifugal force to said concrete mix.

References Cited in the file of this patent UNITED STATES PATENTS 1,576,127 Austin Mar. 9, 1926 1,807,053 Vicenzi May 26, 1931 1,895,740 Ukropina Jan. 31, 1933 1,954,904 Walter Apr. 17, 1934 2,008,074 Isman July 16, 1935 2,109,421 Halkyard Feb. 22, 1938 2,166,175 Porter July 18, 1939 2,296,018 Boyle Sept. 15, 1942 2,614,312 Rankin et al Oct. 21, 1952 2,671,260 lessen et al Mar. 9, 1954