US3746494A

US3746494A - Apparatus for making concrete tubes

Info

Publication number: US3746494A
Application number: US00188823A
Authority: US
Inventors: F Gauger
Original assignee: PFEIFFER KG F; PFEIFFER MASCHF ETTLINGEN
Current assignee: MASCHINENFAB ETTLINGEN DT; PFEIFFER F KG DT; PFEIFFER KG F; PFEIFFER MASCHF ETTLINGEN
Priority date: 1968-03-20
Filing date: 1971-10-13
Publication date: 1973-07-17
Anticipated expiration: 1990-07-17
Also published as: CH481732A; AT277035B; US3649727A; FR2004303A1; DK121847B

Abstract

An apparatus for producing concrete tubes using a vertical tubular mold with a rotating piston-like pressing device moving upwards axially inside the mold. The piston-like pressing device is operated in such a manner that as the torque required for rotation of the piston-like pressing device decreases owing to a decrease in the supply of concrete, the rate of upward travel of the piston is decreased. An impeller is located above the pressing device which can be rotated at a higher speed and in opposed sense with regard to the rotational speed and sense of rotation of the piston-like pressing device.

Description

Waited States Patent 1 Gauger 1 July 17,1973

[ APPARATUS FOR MAKING CONCRETE TUBES [75] Inventor: Friedhelm Gauger,Ettlingenweier,

Germany [22] Filed: Oct. 13, 1971 [2]] Appl. No.: 188,823

Related US. Application Data [62] Division of Ser. No. 806,111, March 11, 1969, Pat.

[30] Foreign Application Priority Data Mar. 20, 1968 Austria A 2781/68 [52] 11.8. C1. 425/262 [51] Int. Cl. B28b 1/34 [58] Field of Search 425/117, 254, 260,

[56] References Cited UNITED STATES PATENTS 3,276,091 10/1966 Pausch 425/262 3,096,556 7/1963 Woods 425/262 1,502,509 7/1924 MacTarnaghan.... 425/117 1,616,816 2/1927 Martin 425/460 2,178,015 10/1939 Brunetti.... 425/262 2,193,286 3/1940 LaDue 425/460 2,641,818 6/1953 Eschenbrenner 425/262 Primary Examiner.l. Spencer Overholser Assistant Examiner-John S. Brown Attorney-Werner W. Kleeman [57] ABSTRACT An apparatus for producing concrete tubes using a vertical tubular mold with a rotating piston-like pressing device moving upwards axially inside the mold. The piston-like pressing device is operated in such a manner that as the torque required for rotation of the pistonlike pressing device decreases owing to a decrease in the supply of concrete, the rate of upward travel of the piston is decreased. An impeller is located above the pressing device which can be rotated at a higher speed and in opposed sense with regard to the rotational speed and sense of rotation of the piston-like pressing device.

10 Claims, 4 Drawing Figures 1 APPARATUS FOR MAKING CONCRETE TUBES CROSS-REFERENCE TO RELATED APPLICATION The present application is a divisional application of my copending U. S. application, Ser. No. 806,1 1 1, filed on Mar. 11, 1969 and entitled Making Concrete Tubes," now U. S. Pat. No. 3,649,727, granted Mar. 14, 1972.

BACKGROUND OF THE INVENTION The present invention relates to the production of concrete tubes with the help of a rotating tube forming unit or male mold which rotates in a female mold defining the external dimensions of the tube produced. With such type apparatus concrete is deposited on an impeller on the top of a piston-like pressing device and is thrown radially outward through the action of centrifugal forces.

According to a prior art method of production of the general type and as described in US. Pat. No. 3,096,556, where the tube forming unit is steadily moved upwards as it rotates, it has been found that the degree of compaction of the tube is not constant so that there are present local variations in strength.

Further, previously proposed arrangements, such as disclosed in French Pat. No. 1,231,155 and U. S. Pat. No. 2,64l,818, have been designed to produce concrete tubes with such a rotating tube forming unit having a pressing device which is provided with lateral sliding and sealing runners or rails. This tube forming unit is provided with a piston and a stationary cylinder having a chamber connected with a pressure duct, the pressure in the chamber and the thrust acting upon the runners or rails can be adjusted by setting the spring of a valve in the pressure duct. It has, however, been found that variations in the rate of supply of concrete in the unset condition cause variations in the density of the pipe wall.

SUMMARY OF THE INVENTION Hence, from what has been stated above it will be seen that the prior art is still in need of improved equipment for the fabrication of such tubes which is not associated with the aforementioned drawbacks and limitations of the state-of-the-art equipment. Therefore, a primary objective of the present invention is to provide a new and improved apparatus for the fabrication of tubes which effectively and reliably fulfils the existing needs in the art and which is not associated with the afore-mentioned drawbacks of the prior art construction.

Another and more specific object of the present invention relates to an improved construction of apparatus for the production of tubes possessing a substantially even degree of compaction throughout their entire length.

Still a further significant object of the present invention relates to a novel construction of apparatus for the production of tubes wherein the impeller serving to centrifugally propel unset concrete into a mold can be driven at a greater speed than the speed of rotation of the pressing device located beneath such impeller, to thereby improve upon the admixing of the concrete and its compaction as conditions require.

Yet a further significant object of the present invention relates to an improved construction of apparatus for the fabrication of concrete pipes wherein the impeller for centrifugally propelling the concrete into the mold can be driven at a greater rotational speed than a pressing device situated below the impeller for acting upon the concrete located between the pressing device and the mold, and further wherein the impeller can be driven in an opposite rotational sense from the rotational sense of the pressing device, in order to be able to improve upon the quality of the finished tube or pipe product so produced.

Now the method in accordance with this invention may be defined as residing principally in the features that the torque which is supplied by the drive motor to the male mold and which varies in accordance with the rate of supply of the concrete, is detected or measured. The rate of lifting of the tube forming unit is decreased when there is measured a decrease in the amount of torque and increased when there is measured an increase in the torque.

Apparatus for putting this invention into practice can comprise a pressing head or tube forming unit, comprising a driven impeller or distributor disc with impelling blades extending away from the axis of rotation, and a separately driven pressing device or smoothing roller unit. An important feature of the invention in this apparatus is that the tube forming unit is driven by a hydraulic motor connected with a pressure duct which supplies oil under pressure from a pump and is connected with a pressure measuring or detecting device which reduces the amount of energy supplied to a tube forming unit-lifting means when there is a decrease in the supply pressure of the hydraulic motor causing the tube forming unit to rotate, and vice versa. In this arrangement use is made of the discovery that the degree of compaction of a tube is connected physically with the torque supplied by the hydraulic motor. The latter is again proportional to the pressure of the oil supplied to the hydraulic motor so that the magnitude of the pressure is an indication for the degree of compaction of the concrete tube. According to a further important aspect of this development the impeller is driven at a greater rotational speed than the rotational speed of the pressing device and in the opposite sense from the rotational sense of such pressing device.

In accordance with a preferred embodiment of the invention the means for lifting the tube forming unit is in the form of a hydraulic ram suitably connected with the tube forming unit and connected by a pressure oil supply pump by means of a duct which is connected with a valve. This valve is responsive to the supply pressure of the hydraulic motor and connects the ram to a greater or lesser extent with an oil container as the pressure in the hydraulic motor supply duct varies.

With the prior art method discussed above use is made of a tube forming unit assembly which comprises an impeller disc which is connected with a'drum-like moving piston. A disadvantage of this construction is the comparatively large height of the assembly. Furthermore, part of the power supplied by the drive motor of the impeller shaft is lost owing to friction between the smoothing piston arrangement and the adjacent concrete of the tube wall. Since the centrifugal force is a function of the speed of rotation of the distributing disc and any increase in the speed of the latter is limited owing to friction of the smoothing piston connected with it, compaction of the concrete centrifugally thrown outwards into a circular formation immediately adjacent the impeller is relatively low. The impeller or impeller disc and the smoothing piston connected with it therefore have a diameter which is less than the subsequent or following arranged pressing means in the form of the roller and smoothing piston UI'IIL A substantial decrease in the constructional height and other advantages can be obtained in accordance with the present invention by forming the impeller from two annular discs of which the lower one has its outer edge directly above the male mold. The two discs of the impeller are made conical so that they direct the concrete downwards and outwards. The lower disc can be provided with impeller blades which enable it to drive the upper disc. The lower disc can be connected with a drive shaft. Such an arrangement of the impeller assembly with the lower outer disc edge immediately above the pressing device is important for correct functioning of the successively arranged pressing device which can immediately respond to the amount of compaction brought about in the circular formation of concrete deposited by the comparatively rapidly rotating impeller. Owing to the pressure responsive means associated with its drive motor, the pressing device can then bring about operation of each lifting means, the operation of which, as mentioned above, is dependent upon the driving torque of the tube forming unit which, in turn, is dependent upon the degree of compaction. The pressing device is therefore not only capable of performing a molding or pressing action and also a smoothing action, but can also act as a sensing or feeling meanswhich constantly examines and determines the degree of compaction of the circular formation or layer of concrete deposited by the impeller and provides a control signal in accordance with the state of this concrete.

Concrete is lowered downwards and passes through an'annular gap between a vertical drive shaft and an interior edge of the upper disc of the impeller. In between the two discs of the impeller the concrete is thrown outwards by means of the impeller blades. Rapid and uniform compaction of the concrete is brought about by the conical construction of the two discs of the impeller which direct the concrete obliquely outwards and downwards. This avoids the disadvantage present in prior art equipment where the concrete is thrown horizontally and as a result is forced upwards through the annular gap between the tube forming unit or pressing head and the female mold, and thus, also avoids the poor compaction occurring with such prior art arrangements in which the concrete is propelled horizontally and not obliquely downwards. Furthermore, compaction is brought about in an advantageous manner immediately ahead of the rollers of the male mold part.

According to a further aspect of the invention it is contemplated that the impeller is separately rotated and then preferably at a higher rotational speed than the pressing device. Further, it is advantageous to drive the impeller in the opposite rotational sense from the direction of rotation of the pressing device. By virtue of these measures it is possible to permit the impeller to revolve as rapidly as is necessary for achieving an intensive and effective propelling of the concrete against the inner wall of the mold. Experiments have substantiated that, in contrast to conventional devices, there is obtained the advantage that there can be utilized concrete with a considerably improved build-up or composition of the granular material; that the large granules present in the additives can deposit to a greater degree than with conventional equipment, and consequently, the proportion of cement is considerably reduced.

Further, during the production of reinforced tubes or pipes, by virtue of these measures, there is additionally realized the advantage that the reinforcement basket is no longer entrained and turned owing to the rotational movement of the pressing head, as was the case with the conventional devices, rather now, owing to the possible opposite rotational movement of the pressing device, such reinforcement basket tends to remain in its set position. The tubes which have been fabricated with the prior art equipment, upon removal from the mold, exhibit torsion fissures or cracks at the concrete tube owing to the prevailing counter-rotational moment of the reinforcement which fissures or cracks, when resorting to the use of the inventive equipment as discussed above, are effectively prevented.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a fragmentary vertical sectional view through an apparatus for making concrete tubes comprising a radially acting tube forming unit or pressing head which is provided with an impeller disc constructed and arranged in accordance with the inven tion;

FIGS. 2 and 3 are respective sectional views taken along the lines II-II and [IL-III respectively of FIG. 1;

and

FIG. 4 is a diagrammatic view of the male mold lifting means and associated control as contemplated in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As can be seen from the drawings, the apparatus comprises an outer or female mold l determining the outer dimensions of the tubes or pipes to be produced and having in its interior cavity a tube forming unit 2, sometimes also referred to as a pressing head. This tube forming unit 2 includes an impeller or distributor 3 and a pressing device 4 in the form of a roller smoothing piston unit. The pressing device 4 is connected with a shaft 5 which is driven by means of a gear wheel 7 attached to its upper end and driven in turn by a pinion 6. At the bottom end of the shaft 5 there is a smoothing piston or plunger 8 with a sheet metal part 9 which is mounted in the manner of a flange and can be replaced when worn. Attached to an upper disc 10 of the smoothing piston 8 are eccentric bolts 11 carrying rollers 12 by means of sealed ball bearings. The upper ends of the rollers 12 are covered by a piece of sheet metal 13.

A hollow shaft 16 is carried on shaft 5 by means of

roller element bearings

14 and 15. This hollow shaft 16 is driven by means of a pinion 18 which meshes with a gear wheel 17 fixed at the upper end of the shaft 16. At the bottom end of the latter the distributor or impeller 3 is fixed. It comprises two frusto-

conical discs

19 and 20. The lower annular disc 19 is directly connected with the shaft 16 while the upper annular disc 20 is connected to the lower disc 19 by means of impeller blades 21 which follow spiral curves as shown in FIG. 2. The upper disc has additional impeller blades 22 mounted on it. As already indicated above, the shaft 16 carrying the distributor or impeller 3 is advantageously rotated at a greater rotational speed than the rotational speed of the pressing device 4, and furthermore, impel- [er 3 is rotated in the opposite rotational sense or opposite direction of rotation from that of the pressing device 4.

As appears from FIG. 1 the lower outer edge of the impeller 3, that is to say, the lower outer edge of the disc 19 is located immediately above the pressing device 4 and is consequentially situated closely adjacent the rollers 12. As can also be seen from this figure, the frusto-conical discs extend downwards and outwards away from the axis of the two

shafts

5, 16.

FIG. 4 shows the drive arrangement of the pressing device 4 including means for controlling lifting. In the embodiment shown, the lifting means for the pressing device consists of a piston and cylinder ram unit 23. The rod of the piston 24 of this unit is connected by means of a chain 25 or the like, which passes over pulleys 26 and 27, with the pressing device. If oil under pressure is supplied by a pump 28 into the upper chamber of the ram unit 23, the piston 24 moves downwards so that there occurs lifting of the pressing device and the impeller 3.

For driving the pressing device 4 there is provided a transmission 29 and a driving hydraulic motor 30 which is preferably arranged to run at a constant speed. This motor is supplied by a pump 32 with oil from an oil reservoir or container 33. A pressure oil duct 31 is connected by means of a branch or control 31 with a regulating valve 34. This valve 34 is arranged to control flow of pressurized oil along a branch duct 35 which is connected with the pump 28 and the upper piston space of the ram unit 23. The duct 35 leads to an oil reservoir or container 37. The control or regulating valve 34 has a plunger which can move so as to alter to a greater or lesser extent the degree of overlap of cooperating valve ports in the path of oil along the duct 35 to the oil container 37. This plunger is acted upon; on the one hand, by the pressure of the oil supplied through the duct 31 and the branch duct 31' while, on the other hand, it is acted upon by a spring 38 whose force can be adjusted by setting a suitable nonillustrated screw. In accordance with the setting of the spring 38 the amount of response of the plunger to the pressure prevailing in the duct 31, transmitted via duct 31, can be varied.

The apparatus for producing concrete tubes operates as follows.

Unset concrete supplied to the apparatus passed through the annular gap 100 between the upper edge 20a of the frusto-conical disc 20 and the shaft 16 so as to be acted upon by the blades 21, or alternatively is impelled by the blades 22 on top of the frusto-conical disc 20. Owing to the rotation of the impeller 3 the concrete is impelled centrifugally outwards by the

blades

21 and 22 against the female mold 1.

Since the concrete is conveyed or impelled in a radially outward and downward direction and the rollers 12 of the pressing device 4 are located immediately adjacent to the impeller 3 deposition of the concrete against the wall of the female mold l to a level above the impeller is prevented. Such a deposition ahead of the impeller would lead to the production of a tube with poor compaction. The arrangement ensures that the concrete is placed in a position adjacent to the rollers 12. Despite the small height dimension of the tube forming unit 2, comprising the pressing device 4 and the impeller 3 an extremely rapid compaction of concrete in the mold 1 can be brought about. It has been found that the degree of compaction of a tube is physically connected with the torque of the hydraulic motor 30. Since this torque M is proportional to the hydraulic supply pressure p, the supply pressure p is also proportional to the degree of compaction of the tube concrete. If, while the tube forming unit is being moved upwards by the descending piston 24 of the ram, the rate of supply of concrete is, for example, reduced, the torque M of the hydraulic motor 30 is also reduced. Consequently, the pressure p in the duct 31 is reduced together with the pressure in duct 31'. The piston or plunger of the regulating valve 34 is moved upwards by spring 38 and decreases the throttling action in the duct 35. As a result, a larger amount of pressurized fluid medium, e.g., oil under pressure from pump 28 can pass to the oil container 37 instead of passing to the upper part of the ram unit 23 through the duct 36. Consequently, the speed of lifting of the tube forming unit 2 is reduced and more concrete is deposited against the inner wall of the mold in a circular formation so that proper compaction still takes place despite the reduction in the rate of supply of concrete to the impeller. There will then be an increase in the pressure in the duct 31 leading to the hydraulic motor 30 and in the control duct 31 so that the regulating valve 34 will be actuated and its plunger moved downwards against the action of spring 38. This will cause the valve 34 to exert a stronger throttling action so that, consequently, more oil flows from the pump 28 to the ram unit 23. The upward speed of the tube forming unit will be consequently increased and after a short time will reach a steady value in harmony with the decreased rate of supply of concrete.

With the help of the regulating valve a constant supply pressure is maintained for the hydraulic motor so that there is a constant degree of compaction of concrete during the formation of the tube. Since this pressure depends upon the setting of the spring 38, adjustment of the spring setting or bias by means of the screw can be used to set the supply pressure of the motor 30 at a higher or lower level, so that, in effect, the screw for setting the spring can be used to set the degree of compaction of the concrete.

Instead of the hydraulic motor used as a drive motor in the embodiment described, it is also possible to use an electric motor. In this. case the instantaneous power level of the electric motor is measured and caused to operate a moving coil regulator taking the place of the hydraulically controlled regulating valve. Since, however, this arrangement is generally more elaborate than the hydraulic arrangement the latter is preferred.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. ACCORD- INGLY,

What is claimed is:

1. An apparatus for molding concrete tubes comprising:

a. an upright female mold having an interior surface defining a mold cavity possessing a substantially vertical axis;

b. a piston-like pressing device disposed within said female mold;

c. means for rotating said pressing device within said mold cavity about said vertical axis of said female mold cavity;

d. lifting means for moving said pressing device along said axis of rotation;

rotary smoothing rollers forming part of said pressing device aligned for rolling upon concrete located between said pressing device and said female mold;

f. an impeller arranged above said pressing device for centrifugally propelling unset concrete into a circular formation against the interior surface of said female mold into a position to be worked by said pressing device, and

g. means responsive to operation of said rotating means for regulating the speed of operation of said lifting means as a function of the torque exerted by said rotating means upon said pressing device, so that during decrease of said torque the lifting speed of said pressing device decreases, and during increase of said torque the lifting speed of said pressing device increases.

2. An apparatus as defined in claim 1, further comprising: a hydraulic ram forming part of said lifting means, a supply pump, first duct means connecting said supply pump with said hydraulic ram, second duct means connecting said first duct means with said responsive means, said responsive means including valve means, reservoir means communicating with said valve means for receiving hydraulic fluid medium, third duct means for supplying fluid medium to said rotating means for said pressing device, and fourth duct means connecting said third duct means with said valve means for causing said valve means to open when the pressure in said third duct means decreases and to close said valve means when the pressure in said third duct means increases.

3. An apparatus as defined in claim 2, wherein said valve means conprises a plunger arranged in a cylinder, one end of said cylinder being connected with said fourth duct means, said valve means further comprising a spring at an opposite end of said plunger, said valve means providing an infinitely variable throttling action.

4. An apparatus as defined in claim 3, wherein said spring can be adjusted to regulate the degree of compaction of the concrete.

5. An apparatus as defined in claim 1, wherein said impeller comprises two substantially superimposed spacedly arranged frusto-conical discs and impeller blades arranged therebetween, said discs being disposed to throw the concrete in a downward and outward direction.

6. An apparatus as defined in claim 5 further comprising impeller blades mounted on and above the uppermost one of said two discs.

7. An apparatus as defined in claim 5, wherein said impeller blades are substantially spiral in shape.

8. An apparatus as defined in claim 1, further including means for rotating said impeller at a greater rotational speed than the rotational speed of said pressing device.

9. An apparatus as defined in claim 8, wherein said rotating means for said impeller serves to rotate said impeller in a direction opposite to the direction of rotation of said pressing device.

10. An apparatus for molding concrete tubes comprising:

b. a piston-like pressing device disposed within said female mold;

d. lifting means for moving said pressing device along said axis of rotation;

e. an impeller arranged above said pressing device for centrifugally propelling unset concrete into a circular formation against the interior surface of said female mold into a position to be worked by said pressing device; and

f. means for separately driving said impeller at a greater rotational speed than the rotational speed of said pressing device in order to obtain an increased degree of compaction of the concrete, said driving means for said impeller serving to rotate said impeller in a direction opposite to the direction of rotation of said pressing device.

i 10! l l

Claims

1. An apparatus for molding concrete tubes comprising: a. an upright female mold having an interior surface defining a mold cavity possessing a substantially vertical axis; b. a piston-like pressing device disposed within said female mold; c. means for rotating said pressing device within said mold cavity about said vertical axis of said female mold cavity; d. lifting means for moving said pressing device along said axis of rotation; e. rotary smoothing rollers forming part of said pressing device aligned for rolling upon concrete located between said pressing device and said female mold; f. an impeller arranged above said pressing device for centrifugally propelling unset concrete into a circular formation against the interior surface of said female mold into a position to be worked by said pressing device, and g. means responsive to operation of said rotating means for regulating the speed of operation of said lifting means as a function of the torque exerted by said rotating means upon said pressing device, so that during decrease of said torque the lifting speed of said pressing device decreases, and during increase of said torque the lifting speed of said pressing device increases.

10. An apparatus for molding concrete tubes comprising: a. an upright female mold having an interior surface defining a mold cavity possessing a substantially vertical axis; b. a piston-like pressing device disposed within said female mold; c. means for rotating said pressing device within said mold cavity about said vertical axis of said female mold cavity; d. lifting means for moving said pressing device along said axis of rotation; e. an impeller arranged above said pressing device for centrifugally propelling unset concrete into a circular formation against the interior surface of said female mold into a position to be worked by said pressing device; and f. means for separately driving said impeller at a greater rotational speed than the rotational speed of said pressing device in order to obtain an increased degree of compaction of the concrete, said driving means for said impeller serving to rotate said impeller in a direction opposite to the direction of rotation of said pressing device.