US2734481A

US2734481A - Sand core dipping machine

Info

Publication number: US2734481A
Authority: US
Publication date: 1956-02-14
Anticipated expiration: 1973-02-14

Description

Feb. 14, 1956 JOHNSON ET AL 2,734,481

SAND CORE DIPPING MACHINE Filed Oct. 27, 1952 3 Sheets-Skeet 1 INVENTORS BER TIL. JoH/vso/v WILLARD C. SHAW M A TTO mvsys Feb. 14, 1956 JOHNSON ETAL 2,734,481

SAND CORE DIPPING MACHINE Filed Oct. 27, 1952 3 Sheets-Sheet 3 INVENTORS BERT/L Jon-5o- WILLARD C. SHAW Zia/v ATTORNEYS United States Patent SAND cone DIPPING MACHINE Bertil Johnson and Willard C. Shaw, Anderson, lnd., as-

signors to General Motors Corporation, Detroit, llilClL, a corporation of Delaware Application October 27, 1952, Serial No. 317,004

7 Claims. (Cl. 118-421) This invention relates to the dipping of core elements or units used in a foundry, such as sand cores used in the casting of various structures. The sand cores are of rather fragile construction to such an extent that they might be fractured or destroyed by the shock of moving or stopping their motion suddenly.

In the present instance trays of sand cores are loaded in an invertable or rotatable rack and are supported in such position that a bucket of coating material may be raised to such a position beneath the racks that the core units may be dipped in the core coating material without movement of the core units themselves. The normally immersed bucket in a supply of core coating material has a flap valve for replenishing of coating material during movement of the bucket, and in its lowest position actuates a switch that permits rotation of the rack in that position only. Power means are provided for raising the bucket, and for rotating the rack, including the use of electro fluid valves with fluid pressure actuators, and switches. Power means rotates the rack about a horizontal axis through 180, and includes a cam plate on the shaft of the rack and a pivoted link connected with an actuator, that effects a slow start and a slow stop motion of the rack at both ends of the actuator movement. The cam and link relation is such that the intermediate movement between the start and stop of the rack rotation is accelerated from the beginning to the mid point and is then decelerated.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. l is a vertical section through a clipping machine, showing the relation of supply tank bucket, rotatable rack and power means for operation thereof.

Fig. 2 is a side view of the machine showing the rack inverting mechanism and linkage, substantially as indicated by the arrow of Fig. 1.

Fig. 2A illustrates the intermediate step during rack rotation.

Fig. 3 tion.

Fig. 4 is a sectional view of the machine as indicated by the line and arrows 4-4 of Fig. 1.

Fig. 5 is a similar view with parts in a different position.

Fig. 6 is a circuit diagram of the control circuit.

The core dipping machine illustrated in the drawings comprises a plurality of post members, such as 10 and 12, connected together at the top by bridge member 14, a stringer 16 and such other structural elements as may be necessary. Surrounding the lower end of the

members

10 and 12 there is a tank 18 resting on a sill or the like 20 adapted to receive a supply of coating material 22, in this case slurry for coating sand cores.

is a similar view with the rack in another posi- Within the tank there is a rectangular bucket 24 that is normally immersed in a supply of coating material 22 with its top edge 26 below the level of the coating material 22. At opposite ends of the bucket there are eye pieces 28 through which extend rods 30 upwardly and through a plate 32. The rods 30 and plate 32 constitute a bail for the bucket 24, and the plate 32 is fitted with screw 34 anchored against turning by cap screw 36, the screw 34 having adjustable connection with a rod 38 connected with a piston in a fluid pressure cylinder 40. In the bottom wall 42 of the bucket there is an opening 44 covered by a flap valve 46 secured thereto at 48.

By this construction, the bucket 24 is adapted for vertical movement upwardly and downwardly in response to action of the fluid pressure device 48. The up and down movement of the bucket is guided by the

frame members

10, 12 and the like. In Fig. 4 the bucket is shown in its lowermost position where it is completely immersed in the coating material 22. In Fig. 5 the bucket is shown in elevated position and in which it is completely filled with the coating material 22. From this elevated position, downward movement of bucket 24 permits coating material 22 from the tank 18 to flow through the opening 44 covered by the flap valve 46 so that the bucket 24 will always be filled with the coating material. When the coating material 22 has a tendency to separate, or the solid material therein tends to settle, raising and lowering of the bucket into and out of the supply will keep the material agitated and thoroughly mixed. In the elevated position as shown in Fig. 5, the bucket is raised to such a position as to partially immerse a core supporting rack 50 and any core elements or units 52 supported on the underside of the rack.

In this case, the rack 59 is mounted on a horizontal shaft 54 which is supported at one end by a pillow block 56 carried by the stringer 16, and journaled at the other end 53 in post member 10. The rack 50 includes a pair of plates 60 secured on opposite sides of the shaft 54 and to the opposite edges of plates 69 are secured end plates 62, the edges of which are secured to rails 64 spaced from cleats 66. The specified arrangement of the end plates 62, the rails 64 and the cleats 66 provide opposing ways 68 for the reception of trays 70 supporting a plurality of the core elements or units 52. 7 As shown in Figs. 4 and 5 this rack 5%) provides for the reception of two trays 70 both in a horizontal position and either above or below the shaft 54, for rotation, and thereby inverting the position of the core elements. According to the showing in Fig. l, the rack 50 is in position to expose the ways 68a as accessible between the post members 12 for loading from a table, shelf or platform 72 associated with the front of the machine. Rotation of shaft 54 through a half circle or 180, will invert the rack so that the tray of cores in the ways 63a is on the underside of the rack, while the ways 68b are uppermost for loading with a tray of cores. In Fig. 4 the rack 50 is shown with a load of core members in both the upper ways and the lower Ways, and Fig. 5 shows the core members in the lower ways being dipped into the coating material carried by the bucket 24.

The rack 50 is rotated about the horizontal shaft 54 for inversion of the core members or units by means of a fluid pressure actuator 74 anchored by the brackets 76 secured to the post and frame member 10. The actuator '74 provides a piston rod 78 pivotally connected at 80 to a link 82 pivotally mounted at 84 to a block 86 attached to the frame member 10. The link 82 is provided 'with two

cam rollers

88 and 90, each of which engages with a cam slot 92 or 94 in a cam plate 96 secured on the rack shaft 54 by a key 98. Linear motion of the actuator rod 78 oscillates the link 82 about the pivot point 84 dur ing which time the

cam rollers

88 and 90 traverse the cam slots 92 and 94 from the position of Fig. 2 through the relation shown in Fig. 2A to the position shown in Fig. 3.

During that traverse the link 82 is rotated through a comparatively small angle, but the rack 50 is rotated 180. During this rotation, link 82 can move at a uniform rate of speed but the cam relation with respect to plate 96 is such that the beginning and ending of rack movement is relatively slow, followed by an accelerated movement toward the position in Fig. 2A, and thence a decelerated movement toward the position shown in Fig. 3.

That is brought about by the relation of the cam rollers and cam slots. Here, the cam slots 92 and 94 are generally similarly shaped but being in an allochiral relation. As seen in Fig. 2, the end portion of the cam slot 94 is substantially parallel or tangent to the arc of motion or movement of the cam roller 90 when the link 82 rotates about the pivot 84. Similarly, the engaging portion of the cam slot 92 bears a similar relation with respect to the cam roller 38. In that instance, movement of the link 82 through a comparatively large angle will effect but slight angular movement of the cam plate 96. By the time the rack 50 has been rotated half-way through its possible movement, the relation of the cam plate and link reaches the position shown in Fig. 2A, where continued rotation of link 82 has the greatest effect on 96 as to relative angular movement. Now, the

rollers

88 and 90 have reached a point in the cam slots where their angular movement is substantially at right angles to the engaging faces of the respective cam slots. Continued rotation of the link 82 brings about the relation shown in Fig. 3. The last end of the movement of the rack is decelerated because of the rollers traversing an are substantially parallel with the engaged surfaces of the respective cams. Thus, in the rotative movement of the rack 50, there is a slow pickup of angular movement which is accelerated through the intermediate path of rotation and then ends in a cushioned stopping movement. Thus relatively fragile core members loaded in the rack may be inverted to the dipping position and returned to the load position without shock or jar which might cause them to fracture or disintegrate.

The raising and lowering of the bucket and the rotation of the rack are accomplished in a definite sequence through the agency of an electrofluid control system somewhat as shown in Pig. 6 for effecting operation of the fluid pres sure actuators 4t and 74. The rack cannot be rotated while the bucket is in any position other than at the bottom of the tank substantially shown in Figs. 1 and 4. When the bucket is in the lowest position a pin 1% operates a microswitch M81 to keep it in a closed contact position. When the bucket is in a raised position a pin Hi2 actuates a microswitch MSZ to open circuit a relay R1. When the rack is in one position, as shown in Fig. 2,

a microswitch M84 is in one circuit closed position to condition a solenoid valve S1 for operation, and when the rack is in the reverse position shown in Fig, 3, switch M84 permits electroconnections with a solenoid valve S2.

The switch M34 is in the nature of a selector switch, and

its operation is effected by engagement or disengagement of the cam plate 96. The pivoted link 82 has a symmetrical cam portion 194 for operating a microswitch M53 for controlling the solenoid valve S3, in turn controlling the flow of fluid pressure to and from the actuator 74.

With specific reference to Fig. 6, electric current is supplied through a main switch SW1 to conductors 1G6 and 1&8, which feed three

parallel circuits

110, 112 and 114. Circuit 110 includes a push button switch PB1 normally open, the microswitch MS1 normally open, but closed when the bucket is in the lower position, and the microswitch M84 which connects either solenoid valve S1 or S2. Circuit 112 includes a pair of contacts C1 normally open, microswitch MS2 which is normally closed but open when the bucket is in the raised position, and the winding of relay R1 which controls the contacts C1, C2 normally open. The circuit 114 includes microswitch MS3 normally connected with circuit 112, but actuated by the pivoted link 82 to complete circuit 114 through normally open contact C2 and a solenoid actuated valve S3. The

solenoid valve S3 controls the flow of fluid pressure to actuator 49 for raising and lowering the bucket. The solenoid valves S1 and S2 control the flow of fluid pressure to and from the actuator 74 for controlling the rotation or inversion of the rack. The relay when energized effects the closing of contacts C1 and C2.

When the machine is in condition for operation, the circuit will be closed through solenoid valves S1 or S2 except for push button switch PBl. Circuit 112 will be closed through part of circuit 114 including microswitch M53 in its upper position connecting with microswitch M82, the relay R1 operating to close contact C1. The solenoid valve S3 in circuit 114 will be deenergized even though contacts C2 are closed, because switch M83 is in the upper position. For rotating the rack the operator closes push button switch PBl by which either solenoid valve S1 or S2 is energized to effect operation of the actuator 74 which rotates the rack. When the rack rotates or turns over the microswitches M54 and MS3 are reversed, which cuts in the other solenoid valve S2 or Si, and completes the circuit 114 for energization of the solenoid valve S3. Solenoid valve S3 controls the flow of fluid pressure to and from actuator 40 for raising the bucket to the upper position. As the bucket raises, microswitch M51 is opened to deenergize the solenoid valves S1 or S2 and microswitch M52 is then opened which deenergizes relay R1 followed by opening contact C1 and C2. Solenoid valve S3 being opened circuited the bucket is lowered, which recloses microswitch M82 and finally closes microswitch MSl.

That completes the sequence of operations and conditions the machine for a second operation. The rack with a load of core units has been rotated to place them on the underside of the rack, and the bucket has been raised with its supply of coating material to the position shown in Fig. 5 where the core elements are coated followed by lowering the bucket to normal position. A second closing of the push button switch P131 first effects closing of the circuit 110 which energizes the other of the solenoid valves S1 or S2 effecting rotation or inversion of the rack. Now, the coated core units will be on top of the rack, and may be replaced by a new set to be coated. The microswitch M51 is provided so that the rack cannot be rotated except when the bucket is in the bottom position.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A core dipping machine comprising, in combination, a tank of dipping material, an invertible core supporting rack rotatably supported over said tank, a buck et immersed in the tank beneath the said rack adapted to be lifted for raising a quantity of dipping material, power means for inverting the rack when the bucket is in the bottom of the tank, said means for inverting the rack including a cam plate and a crank arm having interengaging means for accelerating the rotating motion of the rack from a slow start of the said inversion and for decelerating the stop of said inversion, and means preventing anyinversion of the rack while the bucket is being lifted.

2. A core dipping machine comprising in combination, tank means providing a supply of core dipping material, a core supporting rack rotatably mounted over said supply, means for rotating said rack from a loading position to a dipping position, a vertically movable bucket for lifting a quantity of dipping material from said supply tank for coating cores supported by said rack, means for rotating said rack and means preventing rotation of the rack when the bucket is in other than its lowermost position.

3. A core dipping machine comprising in combination, means providing a supply of core dipping material, a bucket normally immersed in the core dipping material, means for raising the bucket and a quantity of dipping material above the level of the core dipping material, a rotatable rack for supporting a tray of core members over the bucket means for rotating the rack for moving the trays from a loading position to a dipping position, means controlled by the bucket preventing the rotation of the rack while the bucket is being raised, and means permitting rotation of the rack when the bucket returns to its immersed position.

4. The combination set forth in claim 3 wherein the bucket has a flap valve for admission of dipping material to the bucket while it is being immersed.

5. In a core dipping machine the combination comprising, a rotatable rack for supporting trays of core units to be dipped, means for rotating the rack from a core loading position to a core dipping position, said rack rotating means including; a cam plate rotatable with said rack, a pivoted link adapted to rotate said cam plate, and means connecting said cam plate and pivoted link, said means being adapted for starting and stopping the rack rotation slowly and without shock.

6. The combination set forth in claim 5 wherein the connecting means include a cam plate having S-shaped slots therein and the link includes rollers engageable in said slots.

7. The combination set forth in claim 6 wherein, the connecting means includes a cam plate having a pair of curved cam slots, and the pivoted link provides a pair of rollers engageable in the cam slots, said cam slots being of allochiral relation and having portions cooperable with the cam rollers to efiiect relatively small angular movement of the rack at the start of rotation of the pivoted link and at the stop of movement thereof, as the rollers traverse said slots.

References Cited in the file of this patent UNITED STATES PATENTS 1,064,235 McCan June 10, 1913 1,258,071 Winter Mar. 5, 1918 1,585,880 Schnell May 25, 1926 2,159,850 Haynes May 23, 1939 2,529,488 Coppock Nov. 14, 1950 2,617,163 Jeter et al. Nov. 11, 1952