GB2024070A - Convertible sand core machine - Google Patents

Abstract

The machine is adapted for the automatic production of sand cores by the cold box process, the machine being convertible from vertically or horizontally parting core boxes using interchangeable parts. A mixture of sand and binder is delivered through a blowhead into a core box and the core produced is cured by a gaseous catalyst e.g. CO2 or SO2 or an amine. The interchangeable parts include two blowheads, two gassing head curing means and two clamping assemblies, one for clamping vertically parting boxes and the other for clamping the horizontally parting boxes.

Description

SPECIFICATION Convertible sand core machine This invention relates to a convertible sand core machine for producing rigid sand cores for use in metal casting. In a particular aspect, this invention relates to a convertible machine for producing sand cores by the cold box process for use with either a horizontallyparting core box or a vertically-parting core box.

Machines for producing said cores for foundry purposes employ a molding mixture comprising sand mixed with a relatively small quantity of a binder therefor. The molding mixture is placed in a core or molding box of iron or other metal having internal contours corresponding to the internal contours of the article to be ultimately produced from the sand core.

One widely known method for producing rigid sand cores is known as the cold box process. In this process, the core box is placed in the core machine and a molding mixture of sand and a hardenable blinder is blown into the core box by a blow valve system which is controlled by an electrical control circuit comprising a plurality of switches and timers.

The hardenable binder is a cold setting resin which reacts with a particular gas catalyst fed through to the core box to cure or set the molding mixture. Although many different gas mixtures may be employed as the catalyst, amine gas is often one of the primary constituents. After the molding mixture is hardened by the reaction with the cold setting catalyst, the gas catalyst is purged from the core box and the core is removed from the machine for use in metal casting. Examples of this cold box process are shown and described in United States Patent 3,038,221 issued to F. Hansberg on June 12, 1962, and United States Patent 3,702,316 issued to J. Robins on November 7, 1972.

Different machines are presently available in the art for producing rigid sand cores, according to the cold box process, some of which are capable of automatic operation. Examples of such machines are the automatic cold box core machine CB-1 6-SA, Redford Bulletin No. 7201; and HCB-22 automatic horizontal cold box core machine, Redford Bulletin No.

76-13; CB-22 SA automatic cold box core machine, Redford Bulletin No. 7501. Recently W. A Zachary showed and described in U.S. Patent 4,082,134, which is incorporated herein by reference thereto, a combined sand core machine useful for either cold box or hot box operation, including making shell cores.

All of these machines are produced by the Foundry Products Division of International Minerals 8 Chemical Corporation, Detroit, Michigan.

One problem encountered in all of these sand core processes derives from the shape of the core. The core box is designed to be separated into halves so that the sand core can be removed after the resin has hardened.

Depending on the shape of the core, the core box is opened either vertically or horizontally.

Heretofore there has not been a machine which could accommodate both types and, therefore, the previous practice has been for a foundry to invest in two machines, one to accommodate vertically-parting core boxes and the other to accommodate horizontallyparting boxes.

Therefore, it is an object of this invention to provide a single convertible machine for accommodating both vertically and horizontallyparting core boxes. This machine overcomes the necessity of having two machines as previously was the case.

Brief Description of the Drawings: Figure 1 is a front view of the apparatus comprising the present invention, including cross sectional views of related parts, as assembly for operation with a vertically-parting core box.

Figures 2 and 2A show the blowing heads for introducing the sand-binder mixture into the core box. Fig. 2 shows the blowing head used for the vertically-parting box and Fig. 2A shows the blowing head used for the horizontally-parting box.

Figure 3 shows the gassing head used for introducing the gas catalyst into the verticallyparting core box. Fig. 3A shows the gassing head used for introducing the gas catalyst into the horizontally-parting gassing head.

Figure 4 shows the cradle assembly for supporting the vertically-parting core box, including the removable front cradle guide.

Figure 5 shows the cradle assembly for supporting the horizontally-parting core box installed for use.

The present invention is a convertible sand core machine adapted to be used with either vertically-parting core boxes or horizontallyparting core boxes. The machine comprises a sand injectionmeans, a gassing head and a cradle assembly for holding the core box.

The convertible features include (a) interchangeable blowing heads, one adapted for use with a vertically-parting core box and one adapted for use with a horizontally-parting core box; (b) interchangeable gassing heads for cold box operation, one adapted for use with the horizontally-parting core box and one adapted for use with a vertically-parting core box; (c) a cradle assembly means adapted for use with a vertically-parting core box having one or more removable cradle platens and a front guide rod, which preferably, but not necessarily, is removable, and (d) a removable cradle assembly means adapted for use with a horizontally-parting core box.

The apparatus is controlled by electrical and pneumatic circuits which are the same irrespective of whether the core box is vertically or horizontally parted. These circuits are known in the art and form no part of the present invention. The electrical and pneumatic circuits are shown, for example, by W. A.

Zachary in U.S. Patent No. 4,082,134. It is also to be understood that hydraulic circuits can be substituted for pneumatic circuits and are regarded as the practical equivalents of pneumatic circuits.

A summary of the basic steps of the cold box process is useful to an understanding of this convertible machine. The machine operator adapts the machine for use with a vertically-parting or horizontally-parting core box.

For the former, the blow head assembly (Fig.

2) and gas head assembly (Fig. 3) for vertically-parting core box are attached to the sand magazine assembly 2 and the gas magazine assembly 4, respectively. The cradle platens 35 and 36 are installed on the cradle assembly 7. If the front cradle guide rod 44 (Fig. 4) is not in place, it is installed at this time. The quick-connect pneumatic tubes are attached to horizontal clamp cylinders 42. Switches S4 to S12 are set for automatic operation and timers 1-TR, 2-TR, 3-TR and 4-TR are set for their respective time periods.

The core box is placed in the cradle assembly 7 and the machine operator then starts the automatic cycle by depressing first the power switch S1 (activating pilot light PL1) and then simultaneously, the two start switches, S2 and S3 (activating pilot light PL2). This activates the horizontal clamp controlled by switch S4 to clamp the vertically parting core box in the cradle assembly 7. The sand magazine assembly 2 then moves to its forward position due to the actuation of the sand magazine arm valve controlled by switch S5.

Vertical clamp cylinder 5 is then actuated by the vertical clamp valve controlled by switch S9 which forces the blow head against the sand magazine assembly 2 which in turn forces the sand magazine assembly against the core box. The blow valve, controlled by switch S6 and timer 1-TR then actuates and blows said from the magazine assembly 2 into the core box. The blow pressure is exhausted upon the actuation of an exhaust pilot valve and then both the vertical clamp 5 and the sand magazine arm assembly 2 retract to their normal position as shown in Fig. 1. The reload valve controlled by switch S7 and timer 2-TR now is actuated and the hopper is energized to refill the said magazine assembly 2 for the next cycle.At the same time, the gas arm valve, also controlled by switch S5, is actuated which moves gas magazine assembly 4 to its forward position over the core box.

Although the vertical clamp cylinder 5 is again actuated by the vertical clamp valve to force the blow head against the gas magazine assembly 4 which in turn forces the gas magazine assembly 4 against the core box, the blow valve is not actuated. The control circuit then successively actuates a low pressure gas timer and a low pressure gas valve (which are located inside the control box), controlled by switch S10, a high pressure gas timer 3-TR and a high pressure gas valve controlled by switch S11, and a purge timer 4-TR and a purge valve controlled by switch S12. After the air purge timer times out and the air purge valve is de-energized, the vertical clamp cylinder 5 and the gas arm assembly 4 retract to their normal position. The machine operator activates the vibrator 60 by depressing foot switch 46.The automatic cycle is now terminated and the horizontal clamp opens automatically to permit manual removal of the core. An emergency switch S13 is provided for interrupting the automatic cycle at any time.

When a horizontally-parting core box is to be used, the machine operator converts the machine accordingly. The sand magazine blow head assembly 50 (Fig. 4) and the gas head assembly 51 which were installed for the vertically-parting core box are removed by loosening bolts 47. Sand magazine blow head assembly 24, Fig. 2A, and gas head assembly 26, Fig. 3A, adapted for use with a horizontally-parting core box are installed in their place as shown in Fig. 5. Cradle platens 35 and 36 (Fig. 4) are removed by loosening bolts 62 and the pneumatic hoses are disconnected. Front cradle guide rod 44 is removed if necessary (in one embodiment of the invention, it is not necessary to remove the front cradle guide rod). Cradle assembly 45, Fig. 5, is installed and secured by tightening bolts 52 in brackets 53.The pneumatic hoses are connected to the vertical core box clamp 54 which moves the horizontal cradle platen 55, on which the core box is placed, upwardly to engage upper cradle platen 56. The horizontal cradle platen 55 and core box are further supported by guide rods 57, of which there are four. Exhaust pipe 61 is provided for the gassing and purge step.

The machine operator programs the machine as before by placing the controls and timers in their proper positions. He then starts the automatic cycle by depressing the power and start switches and the machine performs automatically in the same manner as just described. When the automatic cycle is terminated, the clamp opens automatically and the machine operator manually removes the core.

The preferred embodiment of the convertible core machine of the present invention is shown in Fig. 1. The control box 1 comprises numerous switches, pushbuttons, pilot lights, and programmable timers, which are posi toned on the control box for ready access by the machine operator. They are used for programming the core machine. The construction of the control box and programming the machine are known in the art and form no part of this invention.

A molding mixture of a refractory granular material such as sand and a hardenable sand binder, such as a cold setting resin which is cured by a reaction with a particular gas, or gas mixture, such as triethylamine or dimethylethylamine, is placed in said hopper mechanism 3 prior to the operation of the core machine. The same hopper mechanism includes a primary sand hopper 30, a secondary sand hopper 31, a pivotally mounted frame 32 with handle 33 supporting the hopper and springs 34. A vibrator, not shown, is attached to the hopper to ensure smooth flow of the sand binder mixture.

Positioned directly beneath sand hoppermechanism 3 in Fig. 1 is the sand magazine assembly 2, which includes a shutter plate 23 which permits the sand molding mixture contained in sand hopper mechanism 3 to pass to the sand magazine assembly 2. The molding mixture is held by the sand magazine tube 11 which is connected to sand magazine head 24. The sand magazine tube 11 is supported by an upper magazine arm 1 2 and a lower magazine arm 1 3. The upper arm 1 2 is separated from the lower arm 1 3 by four magazine arm collar shafts 14 which further support the magazine guide ring 1 7. A guide ring bushing 1 6 separates the magazine guide ring 1 7 from the magazine arm collar shaft 14.A guide ring spring 1 5 is positioned around each of the magazine arm collar shafts 14 between the magazine guide ring 1 7 and the lower magazine arm 1 3. Since the sand magazine tube 11 is connected directly to magazine guide ring 1 7 which is supported by guide ring springs 15, the sand magazine tube 11 and the sand magazine head 24 can be moved slightly in a vertical direction upon application of a sufficient force to compress guide ring springs 1 5.

The parallel magazine arms 1 2 and 1 3 are supported at one end by magazine arm main shaft 1 8 which is connected to the bearing 1 9 of the core machine by bracket 63. The attachment of the upper and lower magazine arms 1 2 and 1 3 to the magazine arm main shaft 1 8 permits the sand magazine assembly 2 to move in a horizontal direction from beneath the sand hopper assembly 3 to a position directly above the core box which is placed between cradle assemblies 35 and 36 (Fig. 1), which are adapted to support a vertically-parting core box, or in cradle assembly 45 (Fig. 5) which is adapted to support a horizontally-parting core box.Cradle assemblies 35 and 36 are supported by stanchions 43 attached to the frame. The sand magazine assembly 2 is positioned over the core box by the actuation of magazine arm cylinder 22 which is pneumatically controlled by the control circuit contained in control box 1. The position is the same for both vertically-parting and horizontally-parting core boxes. The magazine arm cylinder 22 is connected by magazine arm eye 21 and magazine arm clevis 20 to the upper magazine arm 1 2. The sand magazine assembly 2 further contains interchangeable sand magazine blow plate 25 for retaining the molding mixture in magazine tube 11.

The interchangeable sand blow plate 25 and sand magazine head 24 shown in Figs. 1, 2, 4 and 5 are adapted to a vertically-parted core box. They are interchangeable with a blow head and sand magazine head adapted for a horizontally-parting core box shown in Fig. 2A. Each blow plate has apertures through which the sand mixture is blown into the core box. The pattern formed by these apertures is determined by the shape of the core and is customized for each job.

The gas magazine assembly 4 is shown in Fig. 1 adjacent to the said magazine assembly 2. It is substantially identical to sand magazine assembly 2. However, in addition to magazine tube 11, upper magazine arm 12, lower magazine arm 13, collar shafts 14, guide ring 17, guide ring bushing 16, guide ring spring 15, magazine shaft 18, arm bracket 19, magazine arm clevis 20 and magazine arm eye 21, the gas magazine assembly contains a gas head 26 which blocks the magazine tube 11 from the gas head 26 and a gas plate 27. Gas is supplied from gas accumulator tank 59 through gas plate 27 by gas line 28 connected directly to gas head 26. Each gas plate has apertures through which the gas is delivered into the core box.

The pattern formed by these apertures is determined by the shape of the core and is customized for each job. Similar to the operation of the sand magazine assembly 2, the gas magazine asembly 4 may be positioned directly above the core or molding box which is placed between cradle assemblies 35 and 36. The horizontal movement of the gas magazine assembly 4 is controlled by gassing arm cylinder 29. The operation of gassing arm cylinder 29 is controlled by the control circuit.

The vertical clamp assembly 5 is located above the sand magazine assembly 2 and the gas magazine assembly 4. The vertical clamp cylinder 5 is pneumatically operated and is controlled by the control circuit contained in the control box. This assembly is operative to force the blow head 37 against the sand magazine assembly 2 and to force the sand magazine tube 11 and head 24 downward by compressing magazine springs 1 5 when the sand magazine assembly 2 is positioned below the vertical clamp cylinder assembly 5 and above the core or molding box. Likewise, the vertical clamp cylinder assembly 5 is operative to force the magazine tube 11 of the gas magazine assembly 4 in a downward vertical direction when the gas magazine as sembly 4 is positioned directly beneath the vertical clamp cylinder 5 and above the core or molding box.The force exerted by the vertical clamp cylinder assembly 5 on the magazine tubing 11 of either the gas magazine 4 or the magazine assembly 2 compresses the guide ring springs 1 5 and forces these assemblies against the top of the core or molding box.

The molding mixture contained in the magazine tube 11 of the sand magazine assembly 2 is deposited in the core or molding box when the sand magazine assembly 2 is positioned directly beneath the vertical clamp assembly 5. The molding mixture is deposited in the core box by the action of compressed air blown against and through the molding mixture which forces the moulding mixture through appropriate blow holes in the sand magazine 25. In addition, the compressed air evenly distributes and firmly packs the molding mixture in the core box. Compressed air from an air source is forced through said magazine assembly 2 by blow valve assembly 6. The blow valve assembly 6 includes a blow valve 38, a blow head 37 and a blow head exhaust element 39.The blow valve 38 is pneumatically operated by the pneumatic circuit which is automatically controlled by the control circuit contained in the control box.

The vertically-parting core box of the present invention is positioned between the left cradle assembly 36 and the right cradle assembly 35 of the cradle assembly 7, which is connected to the frame 10. Each of these cradle assemblies includes a cradle platen 40 which is in direct contact with the core box.

Cradle guide rear rods 41 and front rod 44 support the cradle assemblies 35 and 36.

There are three such cradle guide rods, an upper rod 41 and a lower rod 41 at the back and a front lower rod 44 (Fig. 4). In one embodiment of this invention, the front rod 44 is preferably, but not necessarily, removable when converting the machine for use with a horizontally-parting core box by removing bolts 8 of which there are six, five of which are shown in the drawing. Cradle assembly 35 is movable in an inward horizontal direction along cradle guide rods 41 for the purpose of clamping the core or molding box between the cradle assemblies 35 and 36.

The movement of the cradle assembly 35 is controlled by the horizontal clamp cylinders 42 which are pneumatically operated by the operator using pushbuttons on the control panel and pneumatic hoses on horizontal clamp cylinder 42 which controls cradle assembly 35. Cradle assembly 36 is similarly controlleld by a horizontal clamp cylinder operated by pneumatic control and pneumatic hoses. These hoses are connected with quick disconnect hose fittings and are disconnected when converting for use with horizontallyparting core boxes.

The details of the operation of the horizontal clamps 42, the vertical clamp cylinder assembly 5, the sand magazine arm cylinder 22 and the gas arm cylinder 29 are fully described by W. A. Zachary and will not be described further here.

The horizontal clamp cylinder 42 is connected to the main air supply over an air line through a horizontal clamp operating valve.

The pneumatic operation of the horizontal clamp cylinder 42 enables the cradle assembly 7 to clamp the core box between the cradle assemblies 35 and 36 as shown in Fig.

1. The horizontal clamp operating valve connects the main air supply to the horizontal clamp cylinder 42 to force the horizontal clamp cylinder 42 inwardly. Upon actuation of the horizontal clamp operating valve, the horizontal clamp operating valve shifts to its second position in which the main air supply is connected to the horizontal clamp cylinder 42 which enables the horizontal clamp cylinder 42 to move in the opposite direction.

Thus, the horizontal clamp operating valve controls the direction of movement of the horizontal clamp cylinder 42. The vertical core box clamp 54 operates in the same manner.

The gas supply system for the gas magazine assembly 4 which is used as a catalyst for curing the molding mixture in the cold box process, is automatically controlled by the control circuit. The gas is supplied by accumulator tank 59 which supplies a mixture of carbon dioxide carrier gas or other carrier gas and other gases such as amine to gas lines.

The gas then passes through gas plate 27 to the core or molding box and is utilized as a catalyst for curing the molding mixture contained in the core box. Upon completion of the curing process, the gas operating valves are returned to their normal blocked position and the control circuit actuates air purge operating valve connected between gas line 28 and air line which is connected to the main air supply. The air from accumulator tank 58 is used to purge the catalyst gas from the gas head 26 and the core box. After the purging of the core box, the air purge operating valve returns to its normal position and blocks the compressed air line.

Although the invention has been largely described in terms of cold box operation using an amine catalyst to cure the binder, it will be readily apparent that it is equally useful for processes using CO2 or SO2 for curing the sand-binder molding mixture.

Claims (6)

1. A sand core machine convertible from horizontal core-making using horizontally-parting core boxes to bertically core-making using vertically-parting core boxes comprising a hopper and a magazine for delivering a mixture of foundry aggregate and binder therefor through a blow head into a core box and having a means for curing a core in the core box, curing said mixture of aggregate and binder, and interchangeable parts adapted for use with horizontally-parting core boxes or for use with vertically-parting core boxes, the interchangeable parts comprising.

(a) a blow head adapted to be connected with the aggregate-binder magazine and adapted to engage a vertically-parting core box, the blow head being interchangeable with (b) a blow head adapted to be attached to the aggregate-binder magazine and adapted to engage a horizontally-parting core box, (c) a gassing head curing means adapted to be connected with a catalyst-delivering means and adapted to engage a vertically-parting core box and interchangeable with (d) a gassing head curing means adapted to be connected with a catalyst-deliverying means and adapted to engage a horizontallyparting core box, (e) a removable vertically-mounted cradle assembly having a core box clamp adapted to engage and support a horizontally-parting core box and having a gas collector plate adapted to engage the bottom of the core box and adapted to be removable for vertically-parting core box operation, (f) a cradle assembly comprising one or more horizontally-parting clamps adapted to engage and securely support a vertically-parting core box.

2. The machine of Claim 1 wherein the cradle assembly adapted to support a vertically-parting core box has a cradle guide rod mounted at the front and removable for conversion to using horizontally-parting core box.

3. The machine of Claim 1 wherein the cradle assembly comprises one horizontallymounted clamp.

4. The machine of Claim 1 wherein the cradle assembly comprises two horizontally mounted clamps.

5. The machine of Claim 1 wherein the cradle assembly comprises removable cradle platens.

6. A sand core machine substantially as hereinbefore described with reference to the accompanying drawings.