US2439563A - Manufacture of sand cores - Google Patents

Description

April 13, 1948. R. DAINTY MANUFACTURE OF SAND CORES Filed March 25, 1944 3 Sheets-Sheet l April 13,1948. R. D AINTY 2,439,563

MANUFACTURE OF sAub conss Filed Max ch 23, 1944 3 Sheets-Sheet 2 mil/(May FIG.3'

April 13, 1948. DNNTY f 2,439,563

MANUFACTURE OF SAND corms Filed March 23, 1944 r 3 Sheets-Sheet 5 -7 1- /NVENTOR' 204.4%; izflajifiia Patented Apr. 13, 1948 UNITED STATE MANUFACTURE OF SAND CORES Ralph Dainty, Willenhall, England- Application March 23, 1944, Serial No. 527,714

In Great Britain January 15, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires February 14, 1964 This invention relates to improvements in making cores for castings and refers particularly to the making of cores of substantial length and of uniform cross-section, as for example cylindrical cores for use in casting bearing bushes or the like or cores of square or other polygonal cross-sections.

Such cores are commonly made by hand ramming the prepared sand into a hollow. cylindrical former and this is a slow and laborious operation and depends to a certain extent on the skill of the operator for the uniformity and surface finish of the core.

The object of our invention is to provide means whereby cores of a high degree of accuracy canbe produced rapidly and with a minimum of labour.

According to our invention an number of bores of the required shape for the cores are formed in a stationary block or the like and sand fed into the bores is rammed by a corresponding number of rammers or plungers yieldingly mounted on a frame or carrier which is adapted to be reciprocated by manual or other means.

During the core-making operation the lower ends of the bores in the block may be closed by a plate in contact with the lower face of the block or they may be closed by means such as pegs which are vertically adjustable to vary theeifective length of the bores and hence of the finished cores. The pegs may be moved upwardly at the end of the ramming operation to eject the finished cores from the upper ends of the bores in the block or the plate or the pegs may be withdrawn to allow the finished cores to be ejected from the lower ends of the bores by the ramming plungers.

In making the cores the operator has a supply of prepared sand adjacent the block in which the cores are formed and brings the sand over the block to fill the bores. The frame carrying the rammers is then brought down to ram this sand in each bore simultaneously, the frame is'released more sand is brought over the block to fill up the bore again the frame is brought down and so on until the bores are filled and tightly rammed. A scraper is then traversed over the surface of the block to clear off surplus sand and smooth off the top ends of the cores and the finished cores are ejected out of the bores ready for drying. Only a small number of operations is required to make the cores and the operator simultaneously makes a number of cores corresponding to the number of bores in the block.

The yielding mounting of the rammers in the frame ensures that an equal pressure is applied to the sand in each bore irrespective of whether 1 Claim. (01. 22-10) the bores are equally filled and also ensures that the ramming is effected by a combined impact and squeezing action instead. of by an impact action only. This produces uniform and closely compacted cores.

Thera-mming plungers may be yieldlngly loaded by springs, or the spring-loaded plungers may be replaced by pistons working in air-tight cylinders or by any other means which will allow the plungers to move axially against resilient resistance as the sand in the bores is compressed so that the ramming is effected by a combined impact and squeezing action.

Two practical forms of core-making machine in accordance with our invention are illustrated by way of example in the accompanying drawings in which- Figure 1 is a side elevation of one form of the machine.

Figure 2 is a side elevation of an alternative form of machine.

Figure 3 is a plan of the machine shown in Figure 2.

Figure 4 is a plan of the upper part of the plunger assembly showing'one means for'locking the plunger.

In the machine shown in Figure 1, i0 is a steel block in which are formed a number of parallel vertical bores I l of a cross-section corresponding to that of the cores to be made, the bores extending through the block. The bores are preferably slightly tapered to facilitate the ejection of the finished cores.

The block is rigidly mounted in an opening in a bench l2 by means of frame-bars l3.

A pair of parallel arms 14 of angle or other .rigid section and of substantial length are pivotally mounted at It; on the rear ends of the frame bars l3, and at their forward ends they carry a frame consisting of a pair of parallel plates l6 rigidly connected by spacing studs l1. Slldably mounted in the frame are a series of parallel plungers [8 corresponding in number and spacing to the bores in the block above which the frame normally lies. The cross-sectional dimensions of each plunger are less than that of the bore with which it co-operates and on the lower end of the plunger is fixed a head I9 whichserves for the actual ramming of the sand, the plunger projecting below the frame for a distance equal to or slightly more than the length of thebores. vA coiled compression spring 20 is mounted on each plunger between the plates of the frame and abuts between the upper plate and a shoulder or. collar on the plunger which is urged by the spring against the lower plate and forms a stop limiting the downward movement of the plunger relative to the frame.

The lower face of the head IS on the plunger may be serrated or formed with radial grooves and ribs so that in ramming the sand in the bores the upper surface of the sand is correspondingly broken up and there is effective mating and cohesion between successive layers of sand. A

"transverse bar 22 between the arms l4 in front of their pivot is connected by a substantially vertical link 23 passing through the bench to a lever 24 pivoted at its rear end to a fixed point below the bench and provided with a pedal 25 at its for.. ward end. Thus by depressing the pedal with the foot the operator swings the arms and the frame down to force the plungers into the bores in the block. The return movement is effected by springs 26 which normally hold the arms and frame in the raised position.

During the ramming of the cores the lower ends of the bores in the block are closed by pegs 21 extending upwardly from a plate 28 slidably guided on studs 29 extending downwardly from the block. The plate is vertically movable by a lever 30 which has a pivotal and sliding engagement with a stud 3| 'in a fitting 32 secured to the bottom of the table. When the ramming of the cores is completed the lever 30 is lifted to raise the plate 28 so that the pegs 21 are forced upwardly into the bores in the block I and eject the cores which are then taken away for drying.

In the alternative form of the machine shown in Figures 2 to 4 the plunger assembly is guided to move vertically in a. straight line. Y

A block 40 in which are formed a number of parallel vertical bores is mounted in the front part of a cast base 4i adapted to be secured on a bench 42. Rigidly mounted in sockets 43 in the base are spaced vertical pillars 44 of cylindrical cross-section on which a carriage 45 is guided for vertical movement. Each guide is formed by three pairs of rollers 46 engaging the surface of the rod in planes angularly spaced at 120 apart, the rollers of each pair being spaced apart at a substantial distance in an axial direction. Each roller is preferably mounted on an eccentric spindle in a bracket 41 secured to the carriage so that the rollers can be adjusted very accurately to roll freely on the rods without appreciable play. Rigidly mounted in the carriage is a frame formed by vertically spaced plates 48 in which are slidably mounted vertical plungers 49 corresponding in number and spacing to the bores in the block 40. Each plunger 4 pedal lever 55 but this is not always desirable as if the frame carries a large number of plungers then although the resistance to the movement of each individual plunger may be relatively small a considerable force is required to compress the springs of all the plungers simultaneously in ramming the-cores. This pressure can be obtained by using a high leverage between the pedal lever and the carriage but this entails a long movement of the pedal. To avoid this the pedal lever is preferably arranged to actuatethe carriage through mechanism giving a rapid movement of the carriage from the rest position until the plungers are just entering the bores in the block and then a slowmovement with a considerably higher leverage. One such mechanism is shown in Figure 2 when the lower end of the strap 54 is connected by an inclined link 58 to the pedal lever and carries a grooved roller 59 co-operating with a fixed cam surface 60 of such a form that during the first part of the downward movement of the pedal there is a relatively rapid downward movement of the carriage to bring the plungers down to the block and then on the later part of the pedal movement there is a slower and more powerful movement of the carriage to urge the plungers into the bores in the block as there is a step up in projects below the frame for a distance equal to or slightly greater than the length of the bores in the block and is urged downwardly by a compression spring 50 mounted on the plunger and abutting between the upper plate of the frame and a collar on the plunger adapted to engage the lower plate.

A lug, 5| on the carriage 45 is coupled by a rod 52 passing through the bench to a bracket 53 on the upper end of a strap 54 which is pivotally connected to apedal lever 55. The

carriage with the plunger frame is normally held in the raised position shown in Figure 2 by tension springs 56 connected between the bracket 53 and anchorages 51 on the bottom of thebench, andris-brought down to force the plungers into the bores in the block by depressing the pedal lever 55.

The strap 54 may be connected directly to the the leveragebetween the pedal and the strap 54,

If cores of the full length of the bores in the block are required the bottom ends of the cores may be. closed during the ramming operation by a plate sliding into guides in the base casting so that the plate is held against the bottom of the block.

After the cores have been rammed the plate is slid out of these guides and into others at a lower level so that the plate is then spaced from the bottom of the block by a distance greater than the length of the bores and by bringing the plungers down again the rammed cores are ejected downwardly from the bores and left standing vertically on the plate ready for taking away to be dried.

In the arrangement illustrated the lower ends of the bores are closed during the ramming of the cores by pegs 6| extending upwardly from a plate 62 mounted on the upper ends of rods 63 passing through the bench and through a plate 64 secured to the bottom of the bench. The lower ends of these rods are secured to a bar 65 through which passes a screwed sleeve 66 fitting over a spindle 61 which is secured at its lower end to a lever 68 and-is guided at its upper end in the plate 64. The bar 65 is supported by a nut 69 adjustably screwed on to the sleeve 66.

The lever 68 is pivoted at its inner end by a link 10 to a lug H on the bottom of the bench and adjacent its outer end carries a catch 12 adapted to engage with a lug 13 on the front of the bench.

'Before the cores are rammed the lever is raised until the catch 12 engages with the lug 13. This raises the bar 65 and with it the plate 52 so that the pegs 6| enter and close the. lower ends of the bores in the block 40, the pegs being rigidly supported by the lever 68.

The extent to which the pegs 6| enter the bores and hence the length of the cores is ad-' ends of the bores, a plate or equivalent means preferably being slid on to the bench under the block to receive them.

In ejecting the rammed cores by means of the resiliently-loaded plungers there is a possibility that a core may stick in the'bore until the plunger spring has been compressed for some distance so that the core is ejected with considerable force and speed and may be damaged. To avoid this means may be provided for lockingtheplungers rigidly against movement in the frame during the ejecting of the cores.

One such means is shown in Figure 4. It comprises a plate 14 having'a number of openings corresponding in number and spacing to the plungers which overlies the upper plate of the plunger frame and has a limited sliding movement thereon by means of slots 15in the plate co-operating with the studs 16 and nuts 11 which secure the plates of the frame together. In one position of the plate 14 the openings in this plate register with the upper ends of the plungers which can move freely through the plate while in another position the openings are out of register with the plungers which are then looked against movement relative to the frame and move as a rigid unit with the frame.

While the apparatus has been described above as having the bores in the block vertical and the frame carrying the plungers moving in a vertical direction it will be obvious that for some purposes it may i be desirable to arrange the bores in the block horizontally. in which case the frame will move in a horizontal direction.

The solid block having bores in which the cores are formed and from which they are ejected in an axial direction may be replaced by a split core stock divided in a plane containing the axes of a number of aligned moulds, the two parts of the stock being clamped together while the cores are being rammed and being separated subsequently to allow the cores to beulift'ed out or A turned out on to a grooved plate or core-rest.

Several of such split stocks may be clamped together by quick-acting clamps or the like to form a block which is located in the machine by dowels or other suitable locating means.

Further, while the apparatus has been designed primarily formaking sand cores it can be used for any other purpose where pulverulent material such as core sand or earth has to be compacted into a cylindrical or similar form.

I claim: a

Apparatus for the simultaneous manufacture of a plurality of rod-like sand cores or the like comprising a plurality of parallel stationary moulds, movable means for closing the moulds at one end during the formation of the cores, a frame guided to move in a path substantially parallel to the axes of the moulds, means for moving the frame towards and away from the moulds, a plurality of plungers corresponding in number and spacing to the moulds yieldingly mounted in and projecting from the frame and adapted to enter and yieldingly ram sand in the moulds, said frame including two spaced plates, one of 'said plates being provided with openings in which said plungers are guided, the other plate being provided with similarly arranged openings and being shiftable in its plane, so that the plungers can move freely through said other plate when the openings of both plates register, but

are locked when the openings are out of registry.

RALPH DAINTY.

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

UNITED STATES PATENTS Augustine Jan. 8, 1907 Schwarzkopf Apr. 16, 1907 Ford Sept. 16, 1913 Graves May 27, 1919 Smith June 16, 1925 Elton et al. Dec. 3, 1929 Sebring Oct. 23, 1934 Hammer Oct. 10, 1893

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