US2882565A - Core making machine - Google Patents

Description

, April 21, 1959 Filed Sept. 15. 1954 ,c. L. SELBY CORE MAKING MACHINE 3 Sheets-Sheet 1 I Ap 1959' c. SELBY 'coRE MAKING MACHINE 3 Sheets-Sheet 2 Fi1ed Sept. 13. 1954 April 21, 1959 sELBY Z 2,882,565

Filed se t. 1:5. 1954 CORE MAKING MACHINE s sheets-shat s f liliil ihl United htates CGRE MAKING MACHINE Claude Leslie Selby, Birmingham, England, assignor to constructional Engineering Company Limited, Birmingham, England, a British company Application eptember 13, 1954, Serial No. 455,571

Claims priority, application Great Britain September 18, 1953 2 Claims. (Cl. 22-10) This invention relates to core making or core blowing machines of the kind in which the divided material of which the cores are to be made, usually sand mixed with a binder, is fed into a container or magazine into which compressed air is admitted to blow or force the sand through apertures in the base plate of the container and into corresponding apertures in the core box leading to the cavity or cavities in which the core or cores is or are to be formed. It is such machines which are referred to in this specification as of the kind set forth.

Core blowing machines are known in which a cartridge is used to be charged with sand and fitted into the machine. Compressed air applied to one end of the cartridge blows the sand out of the other end into the core box. This method is only suitable for lightly bonded core material and the cartridge has to be removed from the machine forre-charging. Medium or heavily bonded core sands tend to become impacted at the core blowing apertures owing to the ramming effect of the air pressure behind it.

In our'Patent No. 2,409,330 a core blowing machine is described in which air is admitted to the container or magazine through small perforations from an air belt surrounding the lower part of the container or magazine. The many fine streams orjets into which the air is split result in a thorough mixing of air and sand as the sand is agitated by a mechanical agitator.

According to one aspectof the present invention air isadmitted throughperforations from an air belt surrounding the lower part of the container or magazine and through an additional entry in the upper part of the container so arranged that the sand or other core material is agitated by the entering air and becomes intimatelymixed with it.

The term sand is-usedin this specification forconvenience and is intended to refer not only to sand but to other core materials.

The air entry near the upper part of the container is preferably tangential in a cylindrical or conical container so that a swirling motion of the air, and sand entrained with it, takes place inside the container or magazine. In a preferred embodiment according to the present invention the agitation of the sand by this means is so effective that mechanical agitation or stirring is unnecessary.

The air preferably also enters the lower wind belt tangentially for more even distribution of pressure around the periphery of the container or magazine.

In many known core-blowing machines it is necessary to raise the air pressure in the container to a considerable value for satisfactory core-blowing. This results in a considerable consumption of compressed air since the air charged into the container has to be released at each core-blowing operation. With improvement in this respect particularly in view the present invention from another aspect provides a core making or blowing machine of the kind set forth wherein the container is not normally under pressure but is adapted for the momen- 2,882,565 Patented. Apr zl 1959 tary admission of compressed air through entry means so directed that the entering air disturbs the sand within the container from its normally quiescent state, agitates it and mixes it intimately with air, the rise in pressure within the container resulting from said pulse of air forcing sand throughthe base plate into the core box.

An embodiment of the invention will nowbe described byway of example, withreference to the accompanying drawings in which Figure l is a front. elevation of a core-making or blowing machine according to-the-invention.

Figure 2 is a side elevation.

Figure 3 is a sectional side elevation on line 3-3 of Figure 1.

' Figures 4 and 5 are sectional plan views on lines i-.-4 and 5-5 respectively of Figure 3.

Figure 6 is a fragmentary sectional view on line 6- -6 of Figure 5.

In the illustrated embodiment of the invention the sand container or magazine is a cylinder 7 with its axis vertical and slidably supported for limited vertical movement by bearings 8 on upright guide pillars9. The pillars 9 are mounted at their lowerend on a base :10 and support above the cylinder a hopper 11 on to which sand for charging'the cylinder can be loaded. A horizontally slidable trap or door 12 normally closes an opening 13 in the bottom of the hopper 11 through which sand can be passed into the open upper end 14 r of the cylinder 7.

A platform 15 for a core box is slidably mounted on the pillars 9 below the-cylinder. Its height is adjustable by a screw jack 16 of substantial proportions. The nut 17 of the screw jack-is-provided with a hand wheel 18 For vertically divisible core boxes lateral clamping means 21 may be requiredinaddition.

On raising-the platform 15 by angular movement of the jack handle 19 the uppersurface of the core box is brought into contact with the apertured base plate 2t) of the cylinder 7 whichisslightly lifted and urges a rubber ring or grommet 22 811116, top of the cylinder into contactwith the;s lida ble trap ordoor 12 thereby sealing the d pp rn of the l nd ;Q .1. Q P ;i cad e b y m smsnt i t eiads-hand 1191 nth o p i di e tion the cylinder falls with the core box to release the slidable trap door 12 until it is arrested by stops 23 on the pillars 9. As the platform 15 is lowered further the core box is released from the bottom of the cylinder 7 and can be removed and opened for removal of the completed core.

As shown in Figures 3, 5 and 6 at the lower end the cylinder is provided with a double wall providing a hollow annular compartment 25 to which air can be admitted through an inlet port 29 arranged substantially tangentiaily to the inner surface of the wall of the cylinder 7. The inner skin 26 of the double wall is provided with a row of internally countersunk holes 27 covered externally by gauze or finely perforated material 28 through which air can pass in fine jets or streams to be intimately mixed with the sand.

In a cylinder having a capacity of twelve pounds of sand a single row of five-sixteenths of an inch in diameter holes are used covered by sheet material .024 of an inch thick perforated with one-thirty-second of an inch diameter holes spaced to provide about three hundred holes per square inch.

As shown in Figures 3 and 4 through the side wall at the upper end of the cylinder 7 an additional port 30 arranged substantially tangentially to the inner surface of the wall (see Figure 4) is provided for air admission. Pipes 31 leading to the upper and lower air inlets are joined to a common compressed air feed line 32 controlled by a single valve 33 preferably as illustrated of the spring-loaded plunger type or the like biased to the off position.

One or more core blowing apertures 34 is provided in the lower end face of the cylinder to correspond in number and size with the openings in the core boxes to be blown. I

In operation sand is loaded on to the hopper 11 while the machine is in the unclamped position. The slidable trap or door 12 is opened to allow sand to be moved into the interior of the cylinder. A core box is placed on the platform 15 which is appropriately adjusted for height and then clamped sealing the top and bottom openings of the container. Compressed air is admitted to the cylinder momentarily by the valve 33 to fill'the core box. The machine is unclamped, the core box removed, opened and the core taken out, the core box replaced and the operation repeated as often as necessary. When the machine is unclamped any air remaining under pressure in the cylinder 7 is discharged by the release of the rubber ring seal 22 at the top opening 14 of the cylinder.

The combination of air entry in fine jets or streams from the lower air belt and the swirl efiect produced by the tangential top air entry provides the necessary agitation of the sand to ensure intimate mixing with the air and makes mechanical agitation unnecessary.

This embodiment according to the present invention is simple to construct and not costly. It enables cores to be blown of a size within the total capacity of the container in a very short time, which in the case of a machine having a container capacity of twelve pounds and operating on a compressed air line pressure of ninety pounds per square inch is of the order of one second. It is especially suitable for small cores of which a large number may be very rapidly blown at each filling of the cylinder. Cores can be made of any material normally used for core blowing, including medium bonded core sand, synthetic mixtures and shell mould mixtures.

A conical hopper may be employed in place of the construction shown in Figures 1 to 3.

Other forms of horizontal clamps for the core box may be employed than that shown generally at 21. For example, a cam-ended lever pivoted eccentrically at the back of the fixed part of the clamp 21 with the cam passing through a slot so that its periphery bears upon the clamping face 21a, the single lever swinging in a plane perpendicular to the plane containing the clamping face 21a. The clamps may be operated by compressed air.

4 Compressed air may also be employed for raising the core box platform 15.

If desired a bat-lie disc, raised above the blowing aperture 34 by projections on its under side as shown at 35 may be employed, to prevent dry material running out of the machine but permits material under pressure to pass around its peripheral edge to the aperture 34.

I claim:

1. In a core-making machine the combination of a cylindrical sand container, means for supporting a core box below the container, an aperture sand delivery plate at the base of the container, means for supplying air under pressure to the container for forcing sand through said aperture plate into the core box, entry means for admitting such air under pressure at the lowest part of the cylindrical wall of the container for permeating with air a body of sand within the container and additional entry means for simultaneously admitting air to the upper part of the container the interior of which it enters in a direction substantially along the adjacent interior surface of the container, a base, spaced upright columns mounted'on said base, a sand hopper supported by said columns above the container having an opening for the passage of sand in register with an aperture in the top of the container, a movable trap slidably mounted on said hopper and closing said opening, sealing means on said container for the joint around said aperture and between said trap and the top of the container, guide means slidably supporting said container on said columns for limited axial movement relative to the hopper, means for clamping said container between said hopper and said core box supporting means to cause said sealing means to engage said trap and seal the joint thus enabling the internal pressure of the container to be raised and for unclamping said container to open the joint, to release any residual pressure within the container and to enable the trap to be opened.

2. A core-making machine according to claim 1 wherein the means for clamping the container axially is constituted by the means for supporting the core box below the container, and said supporting means has a movable portion slidably mounted on said columns.

References Cited in the tile of this patent UNITED STATES PATENTS Fea Ian. 23, 1951

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