US2772453A

US2772453A - Foundry moulding apparatus

Info

Publication number: US2772453A
Application number: US416306A
Authority: US
Inventors: Beech Austin Sidney
Original assignee: Foundry Equipment Ltd
Current assignee: Foundry Equipment Ltd
Priority date: 1953-03-16
Filing date: 1954-03-15
Publication date: 1956-12-04
Anticipated expiration: 1973-12-04

Description

Filed March 15, 1954 A. S. BEECH FOUNDRY MOULDING APPARATUS 3 Sheets-Sheet l A. S. BEEcII M33 4,, 1956 A. s. BEECH J 9 FOUNDRY MOULDING APPARATUS Filed March 15, 1954 3 Sheets-Sheet 2 IN VENTJR Arr xr,

LW 4, 1956 A. s. BEECH FOUNDRY MOULDING APPARATUS 3 Sheets-Sheet 3 Filed March 15, 1954 [Mum/ m" A. 5 BER United States Patent FOUNDRY MOULDING APPARATUS Austin Sidney Beech, Leighton Buzzard, England, assignor to Foundry Equipment Limited, Leighton Buzzard, England, a British company Application March 15, 1954, Serial No. 416,306

Claims priority, application Great Britain March 16, 1953 2 Claims. (Cl. 22-36) This invention comprises improvements in foundry moulding apparatus.

The use of shell moulds for making castings in foundries is now well known. The technique involves the use of a moulding sand which is mixed with a syntheticresin and is brought in contact with a hot metal pattern so that a layer of sand and resin coagulates where it is in contact with the pattern and forms a shell which may he, say, about an eighth up to three eighths of an inch thick. After pouring away the loose sand and curing, the shell can be detached from the pattern and used as a mould for making a metal casting. Ordinarily, the metal pattern is of one half of the desired casting only; a second pattern of the other half of the casting is made which provides a second shell, and when the two shells are fitted together and suitably held the casting can be poured between them. For heavy castings the shells need support, and at the present time the operations of closing, clamping and supporting the shells during pouring are in the main still in a very primitive state and take an undue time to perform, compared with the operation of producing the shells. It is an object of the present invention to improve the process in respect of these operations.

The present invention is used in a process of foundry moulding, which comprises the steps of first producing a shell mould, mounting the shell in a moulding box, and ramming the box with sand behind the shell to support it.

By employing two moulding boxes and supporting the shells therein so that their parting faces are level with the edges of the boxes, the boxes can be put together after ramming and the shells can be easily fitted together and poured, with either a vertical or horizontal joint as desired. The moulding boxes do not require any locating pins or the like, as these are already in the shell moulds and a very simple form of box is sufiicient. Any simple means of clamping the boxes together may be provided.

Preferably, the sand used for ramming is applied by a foundry sand-rammer machine. The sand itself is preferably highly permeable, and this quality can readily be achieved because, unlike an ordinary moulding operation, the sand which is rammed does not come in contact with the pattern and does not have to provide a suitable skin for the surface of the casting. Preferably the first part of the sand is allowed to fall into the box by gravity; this part of the sand is not rammed, but it is then backed up by hard-rammed sand.

In order to enable this process to be carried out as above described, that is to say with the first part of the sand falling into the box by gravity and then backing it up with hard-rammed sand, a modification of the ordinary sand ramming machine has been developed for use in carrying out this process. In an ordinary sand-ramming machine there is a ramming-head which comprises an impeller working in a casing with a downwardly directed spout or outlet through which the impeller projects wads of sand at high speed which, on impact with the sand in the mould, become hard-rammed in the mould due to their velocity. The impeller is kept supplied with sand by a belt conveyor mounted on an arm which carries the ramming-head, and which is movable to any desired position above the mould.

According to the present invention in a sand-ramming machine of this type means are provided, to bypass sand from the conveyor before it enters the ramming head and to deliver it into a chute from which it falls by gravity into the moulding box.

The means to bypass the sand may be provided with a convenient control accessible to the operator and operation of this control will enable him rapidly to switch from operation by gravity-delivery through the chute to operation through the ramming head, and vice versa, without necessarily stopping the ramming head. In this way time is saved, the operator does not have to move his position in changing from one operation to another, and the convenient mechanism which the sand rammer possesses for enabling the operator to bring it over any desired part of a mould is utilised both for the gravitvfeed and for ramming purposes.

The following is a description by way of example of one apparatus for carrying the invention into efiect.

In the accompanying drawings:

Figure 1 is a side elevation of part of a sand ramming machine specially fitted for carrying out the process of the present invention;

Figure 2 is a plan of the same;

Figure 3 is a perspective view of a shell-mould resting on a fiat board with a moulding box behind it;

Figure 4 shows the box in position around the board ready for ramming; and

Figure 5 shows two rammed boxes assembled together ready for pouring.

Referring to Figures 1 and 2, the machine comprises a ramming head 11 supported by a bracket 12 from a carrier arm 13. The carrier arm is supported for universal horizontal movement in the usual way. On the head is a guiding handle 14 and within it, driven from a motor by a shaft passing through bracket 12, is a rotating sand impeller. The head 11 has a delivery-spout 15 with a downward opening in the usual way. Sand is conveyed into the head 11 by conveyor 16 and above the belt 16 are two side walls 17, 18 to guide the sand along the conveyor from a sand-receiving position 19 at its upper end. To this it may be delivered by any means desired. The

side walls

20, 21 around the sand-receiving position are higher and there is a back-end wall 22.

The construction so far described is the usual one for sand rammers. However, in the present case a chute 23 is secured to the side of the carrier arm 13 and opens downwardly at its lower end 24, close behind the spout 15 of the ramming head. At its upper end the chute 23 encloses part of one side-wall 18 of the conveyor. Here the side wall 18 is cut away and is replaced by a movable section 25 of sidewall, which carries a triangular bracket 26. The side walls, including the section 25 are made of rubber and the section 25 is stiffened by a backing plate 27 riveted to it. The triangular bracket 26 is pivoted at 28 on another bracket 29, which extends from the other side of the carrier arm 13 across above the conveyor belt 16. An operating rod 30 is pivoted to the apex of the triangular bracket 26 and connects it with a lever 31 on the ramming head 11. If the operator pulls the lever 31 towards him, the section 25 of the side wall is swung across the conveyor, as shown in chain-line at 25a, Figure 2. It then diverts the sand from the ramming head 11 into the chute 23, whence it can fall by gravity, gently, instead of being slung downwardly at high speed.

Referring now to Figures 3 to 5, in making a mould according to the present invention, a shell mould 41 is first made in the usual manner with a flat border 42 at the parting surface in the under face of which are moulded spigots and. recesses in such positions that the spigots on one shell will fit into the recesses in the other. As already stated the shells '41 are made somewhat thinner than usual, which can be brought about by reducing the time of contact of the synthetic shell-moulding sand with the pattern.

The process of making the shells is therefore somewhat accelerated according to the present invention.

A fiat board or plate 33 is taken having in its surface recesses adapted to fit the registration spigots of one of the shells 41. This shell is placed on the board face downwards with the spigots fitting in the recesses of the board as shown in Figure 3. A moulding halfbox 34 is the placed on the board 33 as shown in Figure 4, so that it fits around the edge of the shell. The box is then rammed by the use of a centrifugal sand -rammer as shown in Figures 1 and 2, and the sand employed is a mixture of silica sand and bentonite (or other similar material) having a high permeability and a bond of approximately eight to ten pounds per square inch.

In ramming, in the initial stage, the lever 31 is operated to direct the sand into the chute 23 and it drops by gravity into the box 34 and forms a protective layer of sand over the shell 41. When the operator judges this is suflicient to prevent any risk of the shell 41 being broken by the high-speed wads of sand flung down by the ramming head 11, he operates the lever 31 to put the ramming head in operation, and the mould box 34 is rammed up tightly.

When the box 34 is rammed the back is strickled off and it is inverted. The fellow shell mould is now placed on the first mould so that it fits the spigots and recesses thereof, a second half-mould box 35 is put in position around it, and the second half-mould box is rammed but need not be strickled. The two half-mould boxes are secured together with clamps 36 (Figure 5) and the complete shell mould assembly is ready for pouring.

The time of conducting these operations may be very short. For example with a mould for a casting weighing about, say 33 pounds, including runners, the total time of ramming, strickling and clamping the two half-mould boxes may be very little more than half a minute. A single sand-rammer can keep pace with the output of two shell moulding machines, and even large castings, up to the largest which can be made with shell moulds, can be dealt with satisfactorily. Each shell is supported over its whole surface. The sand rammed in the boxes helps to seal the parting line of the shell moulds and prevents seepage of metal when the casting is poured.

I claim:

1. A foundry sand-ramming machine comprising in combination a carrier-arm supported for universal horizontal movement, a ramming-head mounted thereon and comprising an impeller and means for rotating the same, a belt conveyor on the carrier-arm delivering into the ramming head, a chute fixed on the carrier arm beside the conveyor and having a downwardly directed opening close to the ramming head, guide walls along each side of the conveyor belt to keep sand in place thereon and a movable section in one of said side walls pivoted so that it can be swung obliquely across the conveyor belt to direct sand therefrom into the chute.

2. A sand-ramming machine as claimed in claim 1, wherein a control rod extends from the movable section of the side wall of the conveyor to an operating member above the ramming head.

References Cited in the file of this patent UNITED STATES PATENTS 1,426,615 Sutton Aug. 22, 1922 1,457,113 Langworthy May 29, 1923 1,662,340 Schmiedeknecht Mar. 13, 1928 1,671,589 Kahler May 29, 1928 2,212,510 Clay et al Aug. 27, 1940 2,555,914 Beech June 5, 1951 2,614,303 Duncan Oct. 21, 1952 OTHER REFERENCES Foundry, pages 115, 116, 291 and 292, June 1952.