US2565696A - Concrete projection apparatus - Google Patents

Description

Aug. 28, 1951 y B. MOLLER ETAAL" 2,565,696

CONCRETE PROJECTION APPARATUS Filed Oct. 22, 1947 INVENTOM' Buvili 40 a -oL $42 Lorpensive.

Patented Aug. 28, 1951 CONCRETE PROJECTION APPARATUS Bent Mller and Erik Bjorn Nimskov, Copenhagen, Denmark Application October 22, 1947, Serial No. 781,446 In Denmark October 25, 1946 8 Claims. 1

This invention relates to improvements in concrete projection apparatus and more particularly to such apparatus, known as cement or concrete guns, wherein an air flow is used for spraying a mixture of concrete and water to a surface which is to be coated with a layer of concrete.

The main object of the invention is to provide means whereby the power consumption and hence the weight, dimensions and price of such apparatus may be substantially reduced-as compared to the previously known apparatus of this kind.

Another object is to provide a simplified construction of such apparatus by eliminating the need for certain devices previously used for introducing the concrete mixture into a pressure conduit.

A further object is to provide means whereby waste of material is substantially avoided.

Still a further object is to provide means whereby the quality of the coating applied to the surface to be treated is substantially improved.

In the concrete guns heretofore used for applying a coating of concrete to surfaces of building structures such as walls, pillars or the like the air flow employed for conveying the concrete from a receptacle to the surface to be treated is produced by means of a source of compressed air, the working pressure required for the operation of such apparatus being generally of the order of 1-3 atmospheres. special means must be provided for introducing the granular substance comprising a mixture of sand and cement into a pressure conduit, one end of which is connected to the said source of compressed air thereby producing an air flow through the said conduit, the other end of said conduit terminating in a gun adapted to project the mixture of air and concrete with the addition of a water jet towards the surface to be treated.

The use of compressed air for producing a concrete carrying air flow involves various drawbacks. In the first place, the weight, dimensions and initial cost of the apparatus are determined by the working pressure required for its operation and. since this pressure, as stated, should be of the order of 1-3 atmospheres, such apparatus inevitably becomes relatively heavy, large and ex- Secondly, the fact that the receptacle containing the mixture of cement and sand is subjected to atmospheric pressure, whereas a suitable working pressure must be maintained in the conduit leading from the receptacle to the gun at the other end thereof, special devices such as sluicing members are required for introducing the concrete mixture from said receptacle into Moreover, in such apparatus said pressure conduit. Thirdly, such apparatus require for their operation a relatively large excess of air relative to the amount of granular substance conveyed through the pressure conduit which necessitates that the gun must be held at a relatively large distance from the surface to be coated, thereby involving a comparative waste of material and causing inferior quality of the coating produced owing to the formation of bubbles therein.

According to the present invention these drawbacks are overcome by eliminating the source of compressed air in concrete projection apparatus and using instead thereof a suction conduit for producing an air flow which is utilised to convey the mixture of sand and cement from the receptacle containing said mixture to the surface to be coated by the concrete jet projected there- While the accompanying drawings and the description which is to follow, constitute a disclosure of the preferred embodiments of the invention, it will be understood that various changes may be made within the scope of what is claimed:

In the accompanying drawings:

Fig. 1 is a diagrammatic view of our concrete projection apparatus illustrating the various instrumentalities which control the operation of the same, the upper parts of the figure being shown in a somewhat enlarged scale.

Fig. 2 is an enlarged sectional side view showing details of one embodiment of the invention.

Fig. 3 is a similar sectional side view showing details of another embodiment of the invention.

Fig. 4 is a vertical sectional view taken on the line IV-IV in Fig. 3.

Fig. 5 is a sectional side view similar to that of Figs. 2 and 3 showing details of a third embodiment of the invention.

Fig. 6 is a vertical sectional view taken along the line VIVI in Fig. 5.

Fig. '7 is a sectional side view in a still larger scale showing an improved construction of a nozzle for a concrete gun according to the invention.

Referring to the drawings and more particularly to Fig. 1 thereof, l is a receptacle containing a mixture of cement and sand or the like, 2 is .a conduit leading from receptacle l to a gun 3 having a conical cap 4 forming a nozzle at one end of said gun. 5 is a conduit communicating with the interior of gun 3 and connecting same to the suction end of a rotary pump or blower 8. 6 is a water conduit communicating with the interior of. gun 3 and leading to a faucet or water tap 1. 9 is a conduit leading from the pressure side of pump or blower 8 to receptacle I. I is a prime mover, for instance a Diesel engine, coupled to blower or pump 8.

In order to illustrate the details more clearly parts 3, 4, 6 and T in the upper part of Fig. 1 are drawn in a somewhat larger scale than parts I, 8 and In in the lower part of this figure.

Fig. 2 illustrates the details of the gun 3 in one embodiment of the invention. In this embodiment the gun 3 is made of a substantially tubular body having a flange 23 at one end thereof. In this body an annular channel I is pro vided so as to leave a tubular member 24 forming a second channel I? therein. Channels I5 and I2 communicate with a cylindrical chamber II adjacent one end of gun 3, and channel I5 is provided with an extension |5a having an internal thread 25 at one end thereof. Similarly, the end of channel i2 is provided with a thread 22, said threads 25 and being adapted to connect the gun 3 to the suction conduit 5 and conduit 2 of Fig. 1 respectively. The body of the gun 3 is further provided with a channel It adapted to be connected to the water conduit 6 of Fig. 1 by means of a thread 25 and communicating with an annular chamber 23a within the flange 23 between said flange and a tubular extension 3a of the body 3. An external cap 4 having a cylindrical part 2| is mounted on the tubular extension 301. abutting the flange 23, said cap 4, 2| being mounted by means of a thread l9 in a cylindrical part I411 of an internal conical cap M which is in its turn mounted on extension 311 by means of a thread The two conical caps 4 and i4 provide a nozzle for the gun 3 having an outlet 29. The annular space formed between caps 4 and i4 communicates through passages 29 in part 2| with the annular chamber 23a and hence with channel i6 and the water conduit 6.

In the embodiment of the gun illustrated in Figs. 3 and 4 the main body of the gun comprises two members: an external tubular barrel 3' having a conical extension 4, and an internal tubular member 39 having a tubular extension 32, said members being screwed together by means of threads 3|. The channel I2 having a threaded inlet 22' is substantially axially dis posed within the tubular member 36, while the channel I6 is disposed obliquely with respect to channel l2 and terminates in the projection 32 having a threaded inlet 25'. A projection 21 is arranged within channel l2 adjacent the outlet of channel |6'. The annular chamber l5 communicating with an extension 25b in a projection 33 is formed between the external surface of member 3| and the internal wall of barrel 3. 28 is the outlet of channel i2 communicating with chamber II.

In the embodiment illustrated in Figs. 5 and 6 the gun comprises a body 3 having two substantially parallel external channels I2 and I5" with threaded inlets 22" and 25" respectively. Intermediate said channels l2" and I5" is a third channel It" having threaded inlet 26 and an outlet 38 in an extension 3 3 of the body 3" at one end thereof. A flange 34 is provided at one end of body 3 and adapted to fasten an external cap 49 having an outlet or orifice 39 by means of screws 35. The interior of said cap 49 provides a substantially U-shaped passage between channels I2" and l5".

Fig. 7 illustrates an improved type of nozzle adapted to be mounted on a gun of the kind referred to. This nozzle comprises three consecutive conical caps 4|, 42 and 43 each disposed with its outlet in air flow alignment with the inlet of the consecutive cap and extending into said inlet so as to form annular spaces 41 and 48 between caps 4|, 42 and 42, 43 respectively. The caps 4|, 42, 43 are screwed together by means of threads 43 and 44. The annular spaces 4'! and 48 communicate with the exterior of the nozzle through grooves 45 and apertures 43, said grooves and apertures being shown by way of example only, it being understood that any other means of providing such communications may be used.

The operation of the concrete projection apparatus and more particularly of the gun pertaining thereto is substantially as follows:

By means of the pump or blower 8, Fig. 1, a subatmospheric pressure is produced in the suction conduit 5 connected with suction channels |5a, i512 and |5, |5', and I5 in Figs. 2-6 as the case may be. Thereby an air flow is produced in the concrete conveying conduit 2 leading from receptacle to channel l2, I2, or I2" in either of the embodiments illustrated in Figs. 2-6. This air flow will cause the dry granular substance comprising for example a mixture of cement and sand to be extracted from receptacle I and conveyed into channel I2, |2, or l2" within the gun 3, 3', or 3" where it is mixed with a water jet passing through conduit 6 and channel Hi, It, or l6" thereby producing a wet concrete mixture which, partly owing to the inertia of the granular substance and partly as a result of the action of the water jet, is projected through apertures 29, 29' or 39 onto the surface to be treated. In the embodiment shown in Fig. 2 the amount of water flowing through channel It may be adjusted by means of the adjustment screw 24a and similar arrangements may, of course, be provided in the embodiments shown in Figs. 3 and 5.

In the embodiment of the gun illustrated in Fig. 2 the actual mixture of the dry substance derived from receptacle with a Water jet derived from the source 1 takes place immediately outside the outlet 29, where a conical film of water 5| is formed owing to the passage of the water flow from channel |6 through chamber 23a, grooves 2|! and the annular space H between cones 4 and M. This water film 5| has the double function of providing a thorough mixture of water and cement and sand grains projected through channel l2, chambers H and |3 and the outlet 29, and of providing a kind of screen which serves to prevent air from the outside of outlet 29 to be sucked therethrough and into the suction channel 15.

In the embodiment illustrated in Figs. 3 and 4 the water jet is injected into the channel l2 adjacent the projection 21 formed therein, whereby a protective water film 49 is formed within chambers H and [3, the function of said film 49 being similar to that of 5| shown in Fig. 2.

In the embodiment illustrated in Figs. 5 and 6 channels l2" and I5" together with chamber 3? form a substantially U-shaped passage between conduits 2 and 5. The interior surface of cap 48 adjacent channel I2" is preferably of parabolic shape. The function being air flow passing through the chamber 31 thereby becomes similar to that of the well known cyclonic filters, the concrete mixture being projected through the outlet 39 partly as a result of the cyclonic eifect in chamber 31 and partly under the influence of the water jet ejected therethrough from the outlet 36 of channel 16 which is positioned substantially in fiow alignment with outlet 39 in cap 4E. The water jet forms a protective film 49, within chamber 31 similar to that described with reference to Figs. 1 and 2.

The function of the nozzle construction illustrated in Fig. 7 is to provide turbulent air currents within the spaces intermediate the conical caps 4|, 42 and 43. When a flow of concrete mixture is passing through the nozzle air will be sucked through grooves 45 and apertures 46 thereby producing turbulent currents within the nozzle which will substantially prevent air from the outside of said nozzle to be sucked through the outlet of the external cap 43 and to pass in a backwards direction through the nozzle, i. e. in a direction opposite to the fiow of concrete mixture passing therethrough.

What we claim is:

1. A projection apparatus comprising in combination, hollow gun means for producing a spray of material and having a passage formed in the interior thereof; a receptacle; a conduit communicating at one end thereof with said receptacle and at the other end thereof with said passage in said gun means; suction means communieating with the interior of said gun so as to draw air through said first mentioned conduit and passage, whereby material in said receptacle is sucked through said first-mentioned conduit and passage; and a water conduit communicating with the interior of said gun means.

2. A projection apparatus comprising in combination a receptacle; hollow gun means for producing a spray of material and having a passage formed in the interior thereof; a material conveying conduit connected at one end to said receptacle and at the other end to said passage; suction means communicating with the interior of said gun means for producing a sub-atmospheric pressure therein; and a water conduit communicating with the interior of said gun means.

3. A projection apparatus comprising in combination, a receptacle; a suction conduit; a suction pump communicating at one end thereof with said receptacle and at the other end thereof with one end of said suction conduit; hollow gun means having its interior in communication with the other end of said suction conduit; a material conveying conduit communicating at one end with the interior of said receptacle and at the other end with the interior of said gun means; and water conduit means communicating with the interior of said gun means for conveying a water jet thereto.

4. An apparatus for the projection of a concrete mixture; comprising in combination, a receptacle; hollow gun means; a concrete conduit communicating at one end with said receptacle; suction conduit means; a chamber in one end of said gun means; a first channel in said gun communicating at one end with the other end of said concrete conveying conduit and terminating in said chamber; a second channel disposed in the interior of said gun means substantially coaxially with respect to said first channel and communicating with said chamber; means communicating with said second channel and suction conduit means for connecting said second channel to said suction conduit means; a first conical cap at said one end of said gun formed with an orifice communicating with said chamber within 'municating therewith; means for said gun; a second conical cap mounted in spaced relation to and substantially coaxially with said first cap about the exterior thereof so as to form an annular space between said caps; a third channel within said gun communicating with said annular space; and means for connecting said third channel with a water conduit.

5. A gun for a concrete-projection apparatus comprising in combination, a tubular member having a conical cap at one end thereof; a first inner channel within said tubular member; a chamber forming the terminal of said inner channel at one end thereof; a concrete-conveying conduit communicating with the other end of said channel; a second channel obliquely disposed with respect to said first channel and comconnecting said second channel with a water conduit so as to inject a Water jet into said first channel; a third channel disposed substantially coaxially with respect to said first channel; means for connecting said third channel to a suction conduit; projection means within said first channel, confronting the entrance of said second channel into said first channel and extending to said chamber, whereby said projection causes the water jet to be sprayed within said chamber and said conical cap so as to substantially prevent air outside of said cap from being sucked therethrough into the suction conduit.

6. A gun for a concrete-projection apparatus comprising in combination, a body having two substantially parallel external channels and a third internal channel disposed therebetween; means for connecting one of said external channels to a concrete-conveying conduit; means for connecting said second external channel to a suction conduit; means for connecting the third internal channel to a water conduit an extension of said body containing said third channel therein; a cap mounted at one end of said body and adapted to receive said extension; and an outlet in said cap substantially in water fiow alignment with the outlet of said third channel, the interior of said cap being shaped as a substantially U-shaped communication between said external channels.

7. A gun as claimed in claim 6, the internal surface of said cap adjacent to the first external channel having a substantially parabolic shape.

8. A gun for the projection of a concrete mixture, comprising in combination, a nozzle at one end of said gun; conduit means connected to said gun for conveying the mixture toward said nozzle; said nozzle comprising a plurality of conical caps having inlets and outlets, each cap being positioned with its outlet in air fiow alignment with the inlet of the consecutive one of said caps and extending into said inlet so as to form an annular space between said outlet and said inlet, and each of said annular spaces communicating with the interior of said caps.

BENT MQ'DLLER. ERIK BJQRN NIMSKOV.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,223,586 Johnson Apr. 24, 1917 1,935,977 Geer Nov. 21, 1933 2,231,489 Anderson et a1. Feb. 11, 1941

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