US3059155A

US3059155A - Magnetic chuck

Info

Publication number: US3059155A
Application number: US660154A
Authority: US
Inventors: Harold F Newcomer
Original assignee: Landis Tool Co
Current assignee: Landis Tool Co
Priority date: 1957-05-20
Filing date: 1957-05-20
Publication date: 1962-10-16
Anticipated expiration: 1979-10-16

Description

Oct. 16, NEWCOMER MAGNET-[C CHUCK Filed May 20, 1957 5 Sheets-Sheet 1 FIG.

FIG. 2.

HAROLD E NEWCOMER INVENTOR BY m, flm m W ATTORNEYS Oct. 16, 1962 H. F. NEWCOMER 3,059,155

MAGNETIC CHUCK Filed May 20, 1957 5 Sheets-Sheet 2 HAROLD F. NEWCOMER INVENTOR M m M ATTORNEYS Oct. 16, 1962 NEwcdMER 3,059,155

MAGNETIC CHUCK Filed May 20, 1957 5 Sheets-Sfleet 5 9' I l I HAROLD F. NEWCOMER IN VENTOR ATTORNEYS United States Patent 3,059,155 MAGNETIC CHUCK Harold F. Newcomer, Waynesboro, Pa., assignor to Landis Tool Company, Waynesboro, Pa. Filed May 20, 1957, Ser. No. 660,154 4 Claims. (Cl. 317162) The following specification relates to an improved magnetic chuck for holding round workpieces of magnetic metal in place upon a rotary headstock during operations of turning, grinding, polishing and the like.

Devices of this character must be strongly magnetic in order to hold the workpieces firmly. They must also be proof against undue wear or deterioration during operation.

The improved chuck of which the following is a detailed description satisfies these requirements with numerous improvements and advantages.

It is the purpose of this invention to provide a chuck having a uniform magnetic path on diametrically opposite sides of a faceplate.

It is a further object of the invention to concentrate this magnetic path along a selected diameter for producing a magnetic repulsion in the area normal to the selected diameter.

A further object of the invention is to distribute the magnetic pull uniformly regardless of the diameter of the workpieces being held.

Among the objects of the invention is to provide independent means for completing the path of the magnetic flux between the rear ends of the magnets having opposite polarity.

One of the objects of the invention is also to provide means for ensuring the proper position of the removable polepieces relative to the front ends of the magnets.

Among the objects of the invention is the provision of means for ensuring the proper position of the removable armatures relative to the rear ends of the magnets.

A still further object of the invention is to minimize the volumes of the several constituent parts of the chuck, i.e. the body and faceplate.

Other objects and advantages will be apparent from the following detailed description of the preferred form of the invention as illustrated on the accompanying drawings in which:

FIG. 1 is a front view of the magnetic chuck on its base member;

FIG. 2 is a side view of the same partly in section on the line 22 in FIG. 1;

FIG. 3 is a longitudinal cross-section on the line 33 in FIG. 4;

FIG. 4 is a rear view of the chuck and its mount;

FIG. 5 is a front view of the faceplate alone;

FIG. 6 is a longitudinal cross-section on the line 66 in FIG. 5;

FIG. 7 is a rear view of the faceplate alone and FIG. 8 is a longitudinal cross-section on the line 88 in FIG. 7.

The new magnetic chuck preferably consists of a chuck body 11. This is of non-magnetic material such as brass, ceramics or similar rigid composition. The body has a circular base 12 with holes 13 provided for bolts with which to attach the base to a headstock spindle or the like, not illustrated.

The chuck body has a columnar section 14 in which there are four longitudinal round cavities 15 equally spaced around the axis of the section 14.

The section 14 is fluted to provide concavities 16 between the cavities to make room for screws 40.

Each of the cavities 15 holds a

round bar magnet

17, 18, 1'9 and 20. These magnets have front ends flush with "ice rim 21 on the front face of the section 14, as shown in FIGURES 2. They thus occupy the narrow recess formed within said narrow peripheral rim 21.

The rear ends of the magnets extend into a central recess 22 in the rear of the base 12.

The magnets are arranged so that they are in pairs having the front poles alike. Thus we assume the front poles of

magnets

17 and 20 to be alike, while the front poles of 18 and 19 are of similar polarity opposite from that of the magnets 1'7 and 20. To illustrate this by way of example, on FIGURE 2, magnet 18 is indicated as having its forward end of S polarity, and the forward end of magnet 28 has the opposite polarity N.

Referring to FIGURE 4, the rear ends of

magnets

17 and 19 have polarity of S and N, respectively.

It is, however, a significant feature of the invention that the polarity of magnet 18 is the opposite of that of the adjacent magnet 17. The same is true of the rear end of the magnet 20.

The rear armature 23 of magnetic material is held against the rear faces of the pairs of

magnets

17 and 20, and 18 and 19, respectively. This attachment is maintained by the magnetism of the magnets and the armatures thus provide a closed magnetic path between dissimilar rear poles of the pairs of magnets.

In order to ensure proper position for the armature 23, it is provided with a hole 25 which registers with a corresponding pin 26 in the base of the chuck body.

A cruciform magnetic faceplate 27 is provided to fit against the rim 21 and in contact with the front ends of the magnets. There is one

individual polepiece

28 and 29, and another 30 and 31 opposite and in contact with each forward end of the magnets. Each polepiece is a V-shaped divergent sector. The angular extent of the polepiece is the same as the diameter of the magnets which they overlie so that the edges of the pole pieces are tangential to the magnets.

The faceplate is divided diametrically so that the

polepieces

29 and 30 overlie the

magnets

17 and 20 of like polarity, while the

polepieces

28 and 31 overlie the

magnets

18 and 19, also of like polarity.

The

sectors

29 and 30 are separated from the

sectors

28 and 31 by a gap 3-2. This gap is filled with nonmagnetic metal or cementitious material.

The upper surface of this gap is closed with a wearresistant material 3-3.

Similar wear-resistant ribs 34 extend radially through the centers of each

sector

28 ,29, 30 and 31.

In the rear, the faceplate has a central cone 35 filled with brass, non-magnetic metal or the like. The rear gap 3-2 widens to form a V-shaped channel diametrically across the faceplate. With this arrangement, adjacent surfaces of the combined

sectors

29 and 30 and combined

sectors

28 and 31 are held to a minimum area to reduce leakage between the two pairs of sectors.

Angular filler sections 36 occupy the spaces between

adjacent sectors

28, 29, 30 and '31.

The faceplate is cast or molded into a single block adapted to be mounted upon the end of the section 14 and in contact with the magnet ends. In order to orient the faceplate on the section 14, the latter has a hole 37 which registers with a corresponding hole 38 in the rear of the faceplate. A locating pin 39 in the hole 37 thus ensures proper position for the faceplate.

The faceplate is then bolted in position by means of non-magnetic bolts 40 carried within the section 14 and exposed on the rear to the flutes 16.

This arrangement of magnets and the corresponding faceplate results in concentrating the magnetic path across the gap 32. There is no magnetic path between the

like magnets

17 and 20 on the one hand, and 18 and 19 on the other. The magnetic flux is therefore concentrated between the

sectors

29 and 30 on the one hand, and 28 and 31 on the other hand.

The construction of the polepieces is designed to produce certain desirable results corresponding to the size of the work-pieces. For small workpieces within a certain range of diameter, it is desirable to have a maximum area of contact between the workpiece and the polepiece. Since workpieces within this range are usually of relatively thin material, it is desirable that the maximum angular surface of the workpiece be in contact with the polepiece. For workpieces of larger diameters, the wedge-shaped portion of the polepiece beyond the small range of diameter serves two purposes. It provides complete coverage for each magnet. The space between each wedge-shaped portion of a polepiece eliminates the stray flux which would occur if the polepieces are continuous. Finally, workpieces of larger diameters are also of heavier cross-section and have greater angular surfaces in contact with the faceplate. If the polepieces are presented in an uninterrupted surface, the magnetic attraction between the polepieces and the larger area of the workpieces would be too great.

The construction thus described has peculiar advantages, as earlier pointed out. It is readily built up and can be used with etficiency under all conditions.

While a preferred form of the invention has been de scribed by way of example, suitable variation of minor details can be carried out without departure from the scope of the invention as defined in the following claims.

What I claim is:

l. A magnetic chuck having a non-magnetic body member with a plurality of longitudinal cavities, a bar magnet extending through each cavity, said magnets being arranged in pairs with the polarity of the magnet ends in each pair being alike and opposite to the polarity of the adjacent magnets of adjoining magnet pairs, a magnetic armature on the rear of the body member and in contact with the rear ends of the magnets, a faceplate of magnetic material on the front of the body member, said faceplate having separate pairs of sectors each sector having angul-arly diverging straight sides individually contacting single magnets of the same polarity, said pairs of sectors being separated by non-magnetic material.

2. A magnetic chuck having a non-magnetic body member with a plurality of longitudinal cavities, a bar magnet extending through each cavity, said magnets being arranged in pairs with the polarity of the magnet ends in each pair being alike and opposite to the polarity of the adjacent magnets of adjoining magnet pairs, a magnetic armature on the rear of the body member and in contact with the rear ends of the magnets, a faceplate of magnetic material on the front of the body member, said faceplate having diametrically separated pairs of sectors each sector having straight sides diverging in substantially radial directions and each pair of sectors contacting adjacent magnets of the same polarity, said pairs of sectors being separated by non-magnetic material.

3. A magnetic chuck having a non-magnetic body member with a plurality of longitudinal cavities, a bar magnet extending through each cavity, said magnets being arranged in pairs with the polarity of the magnet ends in each pair being alike and opposite to the polarity of the adjacent magnets of adjoining magnet pairs, a magnetic armature on the rear of the body member and in contact with the rear ends of the magnets, a faceplate of magnetic material on the front of the body member, said faceplate having pairs of sectors with spaced sides diverging in substantially radial directions, and each pair of sectors contacting adjacent single magnets, of the same polarity, nonmagnetic filling sections between adjajcent sectors, the sectors being diametrically separated into pairs of nonmagnetic material with each pair of sectors contacting a pair of magnets of the same polarity.

4. A magnetic chuck having a non-magnetic body member with a plurality of longitudinal cavities, a bar magnet extending through each cavity, said magnets being arranged in pairs with the polarity of the magnet ends in each pair being alike and opposite to the polarity of the adjacent magnets of adjoining magnet pairs, a magnetic armature on the rear of the body member and in contact with the rear ends of the magnets, a faceplate of magnetic material on the front of the body member, said faceplate having diametrically separated pairs of sectors with spaced sides diverging in substantially radial directions and each pair of sectors contacting adjacent single magnets of the same polarity, said pairs of sectors being separated by non-magnetic material of nearly the same size and shape as said sectors, and the opposite inner edges of the sector pairs diverging rearwardly toward the body member so that flux leakage is limited by the small area of adjacent sector surf-aces.

References Cited in the file of this patent UNITED STATES PATENTS 1,105,552 Downes July 28, 1914 1,484,090 Simmons Feb. 19, 1924 1,603,497 Simmons Oct. 19, 1926 2,287,286 Bing et al June 23, 1942