US2138701A - Machine for manufacturing undercut sand molds - Google Patents

Description

NOV. 29, 1938. JEUNE; 2,138,701

MACHINE FOR MANUFACTURING UNDERGUT SAND MOLDS Filed Aug. 5, 1936 2 Sheets-Sheet l INVENTOR FRANK H. LeJEUNE A TTORNEYS Nov. 29, 1938; F. H. LE JEUNE MACHINE FOR MANUFACTURING UNDERCUT SAND MOLDS Filed Aug. 5, 1936 2 Sheets-Sheet 2 FIG.5.

INVENTOR FRANK H. LEJEUNE ATTORNEYS Patented Nov. 29, 1938 UNITED STATES PATENT OFFIQE MACHINE FOR MANUFACTURING UNDER- CUT SAND MOLDS Application August 3, 1936, Serial No. 94,084

1 Claim.

The invention relates to machines for forming undercut grooves in sand molds and has for one of its objects the obtaining of a simple construction of manually operable mechanism for accomplishing this purpose. The invention has for another of its objects to provide an improved construction of combined presser and cutter head. To this end the invention consists in the construction as hereinafter set forth.

In the drawings:

Figure 1 is a vertical central section through the machine; 1

Figure 2 is a plan view thereof;

Figure 3 is an end elevation;

Figure 4 is an enlarged View of a portion of Figure 2 showing the construction of the grooving mechanism;

Figures 5 and 6 are respectively a sectional end elevation and a front elevation of Figure 4;

Figure 7 is a cross section on the line 1-1 of Figure 4.

The machine is more particularly designed for forming annular ribs on cylindrical castings as for instance brake drums or integral brake drums and hubs for vehicle wheels. The molds for such castings are usually formed by patterns having draft in an axial direction and therefore any extension of the mold cavity for forming surrounding ribs must be undercut. With my improved machine this undercutting is accomplished by the relative rotation of an annular table on which the sand mold is supported and a head extending upward through the central opening in said table into the mold cavity and radially adjustable with respect to the axis of rotation. There is also provision for manually efiecting this relative rotation and radial movement so that the operator may quickly perfor the undercutting operation.

In detail, A is an annular supporting frame mounted upon legs B and provided on its upper face with a circular race groove C for a series of balls D. E is an annular table having a corresponding race groove E for engaging the balls D and also provided with a depending portion E having rack or gear teeth E on its under face. The table E is further provided with a detachable top plate F for receiving the mold to be operated upon and which is exchangeable to correspond to different sizes or shapes of molds. This plate is axially registered with the table E by means of dowel pins F depending therefrom and engaging corresponding recesses in the table. The plate F is further provided with upwardly projecting pins F for engaging sockets in the flask G for the sand mold so as to properly register the mold with the table.

Extending transversely of the annular frame A are parallel guide rods H which are secured in position by suitable means such as the nuts H engaging threaded end portions H? and the washers H which latter bear against the outer face of the member A. I is a carriage slidably mounted on the rods H within the annular frame A and extending upward to approximately the level of the top face of the table E. I is a lug projecting upward from the carriage I through the opening in the annular plate F, and J is a detachable head supported on the carriage and centered by the lug I. This head J has projecting upward therefrom the spaced posts J to which are secured the opposite ends of a segmental presser member K. The major portion of the outer face of the member K is of a radius corresponding to the inner face of the cylindrical wall of the mold cavity so that when said member is adjusted radially with the carriage I, it will bear or press against this face. However the end portions of the outer face are rounded to avoid scraping or cutting the sand. The member K is not, however, rigidly mounted on the carriage but is yieldably attached thereto by means of headed guide pins K having a threaded engagement therewith and slidably engaging bearings in the posts J. Springs L located in recesses in said posts above and below the pins K and also engaging registering recesses in the member K serve to yieldably press the latter radially outward to the limit permitted by the headed pins. The member K is further provided with a series of slots K which correspond in position to the location of the annular ribs which are to be formed on the casting. Engaging these slots are cutter blades M the shanks M of which extend radially inward and are rigidly mounted on the head J. In normal position the cutters M are withdrawn into the slots K If, however, the member K is held against radial outward movement during the continued movement of the carriage I, the cutters will be projected from the slots so as to engage the sand of the mold. The arresting of the radial outward movement of the member K is effected by a ring N surrounding the inner edge of the annular, plate F and projecting upward therefrom. This ring has a beveled top face and the member K is provided with a correspondingly beveled lower face so that when these faces engage each other further outward movement of the member K is arrested. However, relative rotary movement of the ring N in the member K is permitted as will be hereinafter described. The length of the slots K is sufficient not only to receive the cutter blades M but to leave an opening in advance of the cutting edge thereof through which the sand may be carried inward into a vertical channel K through which it can escape.

For the purpose of slicking the sand of the undercut or grooved portions of the mold the cutter blades M are formed both to effect the cutting and the shaking. As shown particularly in Figure 4, the portions M of the end or outer faces of the cutter blades are of a radii respectively corresponding to the faces of the completed undercuts or grooves. However, the forward portions M are of smaller radii and furthermore, as shown in Figures 5 and 6 in addition to Figure 4, the forward portions taper forwardly both in radial and axial section. The front ends of the forward portions effect the cutting and the flaring parts of the forward portions M in rear of the front end and also the portions M effect the slicking.

To provide for the fillets which are to be formed at the junctions of the annular ribs and the brake flange, the presser member K is provided in rear of and in peripheral alignment with the slots K with the beads K shown particularly in Figures 4, 5, 6 and '7. These beads have their forward ends tapered both radially and axially to freely enter the undercuts or grooves formed by the cutter blades. The portions of. the beads in rear of the tapered portions however have a section especially in an axial direction to compact and slick the sand to round the corners and thereby provide for the desired fillets.

To perform the work of cutting the grooves in the mold there must first be a rotation of the table. E with respect to the frame and carriage I, and

second a radially outward movement of the member K and cutter blades M-due'to a sliding movement of the carriage I-on the guides H. To manually perform both of these movements the following mechanism is provided. 0 is a shaft which is jou-rnaled in a bearing 0' in the frame A and projects radially outward therefrom. On his shaft is mounted a gear wheel P which is in mesh with the annular or. gear teeth E on the table. Adjacent to the gear wheel P'is a second gear wheel' Q which is .revoluble on the shaft 0 and which is in mesh with the complementary gear wheel R on a shaft S parallel to the shaft 0 and mounted in a bearing S in the frame A. The outer ends of the shafts O and S are provided with squared or polygonal portions '0 and S which correspond in size and are adapted to receive a corresponding socket T on a hand crank T. The inner end of this socket T is provided with clutch teeth T adapted to engage with corresponding clutch teeth Q on the gear wheel Q, the arrangement being such that when the crank T is engaged with the shaft 0 it may either rotate this shaft alone or by moving the clutch teeth T and Q into engagement will simultaneously rotate the gear wheel Q. The shaft S has an inward extension S which is threaded to engage a nut U in the carriage I. 'Ihis'will cause a movement of the carriage on the guidesH whenever the shaft S is revolved either by direct engagement therewith of the hand crank T or through the medium of the gear wheels Q and R. and the clutch engagement between the hand crank T when mounted on the shaft 0. On the other hand, when the crank T is engaged with the shaft 0- but has its clutch teeth 'I out of engagement with the clutch teeth Q, then the shaft 0 alone will be revolved, which through the gear wheel P will communicate rotary motion to the table E.

With the construction as described, the operation is as follows: The sand mold is first formed in the flask G in the usual manner and. this flask is then placed upon the plate F and is registered in axial alignment with the table E by means of the pins F This will also register the ring N with the inner face of the mold cavity. During the placing of the mold upon the plate F and table E the carriage I is in the position where the member K and cutters M are withdrawn radially inward so as to be wholly within the mold cavity and not to interfere with the sand walls After the flask is properly mounted the operator places the hand crank T in engagement with the squared portion 0 of the shaft 0 and pushes it inward far enough to engage the clutch teeth T with the corresponding clutch teeth Q. The shaft is then rotated by the crank which will simultaneously revolve the table E together with the mold supported thereon and will move the carriage I radially outward on the guides 1-1. This will carry the presser member K outward until its lower beveled edgecomes in contact with the upperbeveled face of the ring N at which time the outer face of the member K will be in contact with and press against the inner cylindrical face of the mold and thereby prevent damage-to this face as well-as slick the same. Further outward movement of the member K is then prevented but the continued movement of the carriage will project the blades M from the recesses K thereby shaving away the sand which is carried inward through the slot and dropped through the channel K The blades also compact and slick the sand of the undercuts or grooves. In addition, the beads of the presser member compact and slick the sand at the corners of the undercuts or grooves to provide for the fillets in the casting. During this continued movement, the springs L are compressed. Outward movement .of the blades M is also limited, preferably by a stop formed by a rod V projecting' rearward from the carriage I parallel to its direction 'of movement. This rod'extends through a bearing W on the frame A and has a threaded end portion for engaging lo'cknuts X. Thus by adjusting these nuts the outward movement of the carriage I may be limited asdesired. When this limit is reached the table E may still be revolved by the crank T provided that the clutch teeth T are disengaged from the clutch teeth Q. To withdraw the cutters and presser member K from engagement with the mold, the crank T is transferred into engagement with the shaft S, and by then rotating the crank in the same direction this will impart a reverse "rotation to the screw S from that transmitted from the shaft 0 :and this turn will move the carriage radially inward. During the withdrawal, the presser member K remains in engagement with the sand during the withdrawal of the cutters and then. is withdrawn.

What I claim as my invention is:

In a machine for'undercutt'ing sand molds, the. combination with "a presser member engageable with the wall of :a mold cavity, of a combined cutter-and slick adapted to extend. beyond said presser member :and having at its front end a solid cutting portion :and in rear of said cutting portion :a slicking portion for the entire surface

Images