US2075902A - Electrically operated sizing device - Google Patents

Description

April 6, 1937. A. L. JOHNSON ELECTRICALLY OPERATED SIZING :DEVICE Filed Aprilv 5, 19h35 KD INVEN-ron ARNoLoLdoHNso/v w A 'r'omwsv Patented Apr. 6, 1937 UNITED STATES PATENT OFFICE Arnold L. Johnson, Worcester, Mass., assgnor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application April 3, 1935, Serial No. 14,538

4 Claims.

The invention relates to grinding machines and more particularly to sizing mechanism therefor.

One object of the invention is to provide a Simple and compact sizing mechanism. Another object of the invention is to provide a sizing mechanism which requires no resetting. Another object of the invention is to provide an electric sizing mechanism which may be operated by electric current whose potential is that of commercial power lines. Other objects will be in part obvious or inpart pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements7 and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims,

The single figure of the drawing illustrates a preferred embodiment of the invention and comprises a vertical sectional view through sizing apparatus mounted, by Way of example, on the work carrying table of a grinding machine, and indicating the position of the grinding wheel and the work-piece.

As conducive to a clearer understanding of the present invention, it is noted that the socalled plain grinder is a machine to grind shafts and the like, and in such a machine the work-piece is held between centers carried by headand tail-stocks, while the grinding wheel is carried by a spindle journaled on a slide movable towards and from the work-piece. Such machines being extremely well known I have not illustrated any such in detail herein. While the present invention may be embodied in a plain grinder it may also be used in connection with any other type of grinder, and certain advantages result from its use in a grinder in which the table carrying the work-piece (in a plain grinder the headand tail-stocks are carried by a table which is reciprocable) does not reciprocate. It is noted that even in machines wherein mechanism is provided for reciprocating the work-piece, grinding can be and is performed with the work-piece stationary (as regards reciprocatory translation) and this type of grinding is sometimes referred to as plunge cutting.

In the patent to Cole and Belden No. 1,911,552, granted May 30, 1933, there are disclosed some of the elements of what might be a plain grinder together with a calipering mechanism and grinding wheel feed slide mechanism arranged to stop the in-feed of the grinding wheel when the workpiece reaches a certain denite size, and to withdraw the grinding wheel when the work-piece reaches finished size. Although the sizing mechanism of the present invention is by no means limited to the type of grinder disclosed in the aforesaid patent to Cole and Belden, as it has particular utility in connection with a crankshaft grinder, for example, and although a different cycle of operation might be used from that disclosed by Cole and Belden, and valthough the slide feeding and retracting mechanism used in connection with the present invention need not be that of Cole and Belden, for description of the illustrative embodiment of this invention the machine of Cole and Belden is to be deemed incorporated herein as is also the wheel slide moving mechanism and the circuits, except that the relays need not be used, and for the caliper casing of Cole and Belden, and the mechanism therein and directly connected thereto, there is substituted the mechanism hereinafter described.

Referring now to the single figure of the drawing, the table of a grinding machine is indicated at I. Such a table may carry the head-stock and tail-stock referred to, and may be mounted on V and flat ways, not shown, provided on the machine Vbase for location of the table and, if desired, for reciprocating it. The table I has ways 2, 3 and 4 upon which may be mounted steady rests (not shown) and also the calipering mechanism of the invention, the ways being so formed that mechanism mounted thereon is adjustable in position in a direction parallel to the direction of adjustment or movement of the table.

I provide a base 5 for the calipering mechanism having ways 6, 'I and 8 formed to cooperate with the ways 2, 3, and 4 respectively. The entire calipering unit is thus readily removable from the machine.

The base 5 is hollow as shown, and the movement amplifying part of the calipering mechanism is enclosed therein, there being a removable cover plate 9 to keep dirt away from the mechanism. The right-hand part Ill of the base 5 is massive and has a threaded bore I I into which is fitted a screw threaded plug I2 which may be 'adjusted in elevation and aflixed in any desired position of adjustment by means of a nut I3. The plug I2 has a pair of coaxial bores I4 and I5, the bore I4 having a diameter considerably larger than the bore I5. In the bore I4 is a spring I one end of which abuts against the massive part IIl of the base 5, and the other end of which engages a washer rII afxed in any suitable manner to a calipering plunger rod I8 which slidably and closely ts the bore I5. The rod I8 is thus'urged upwardly in the plug I2, and an adjustable stop may be provided as in the form of a screw i9 extending through a threaded bore 20 in the plug I2, the lower end of the screw I9 being positioned to engage the washer I1 in the bore I4, and the outer slotted end of the screw 7I9 being always available for adjustment.

The lower end of the plunger rod I8 engages a lever 2i which is pivoted on a shaft or stud 22 extending horizontally from the inside of the base 5. The left-hand end of the lever 2I has a downwardly extending projection 23 which extends through a hole 24 in a cover 25 which has an internally threaded rim 2S. byv means of which it is mounted on top of a cylindrical box 21 l fitting in a recess 28 in the base 5. Across the top of the box 21 extends a dielectric diaphragm 29 which may be made of any material which is both resilient and an electric'insulator,` for ex.-

ample a thin disc of hard rubber. A tightunion is secured between the lip of the box 21 and the diaphragm 2.9, an annular portion 30 inside the cover 25 being shaped to. iit the lip 3| of the box 21, and by screwing on the cover 25 very tightly the diaphragm 29 is compressed so as to make a liquid-tight union.

Preferably the box 21 is made of a dielectric or insulating material, or it could be insulated from the base in any suitable manner. The box'21 is filled with mercury 32, and formed on one side of the box 21 is an extension 33, which is. hollow, and which merges into an upwardly extending tube 34. As shown, the box 21, the extension 33, and the tube 34 may be and preferably are an integral piece.

Extending into the mercury 32 in the extension 33 is an electrode 35. Mounted in the bore in the upper end4 of the tubeA 34 is a tube 36A of insulating material and havingY an internal` tapered bore 31. The tube 36 has a head 38 which isdrilled at two places to. form bores intersecting the tapered bore 31, and the head 38.2 has an extension 38a. Metal insets 39 and49 are inserted in the bores, as shown, the inset 39 extending over the extension 38a and down thefside thereof, and

the inset 48 extending in the other direction over the head 38 and down the side of the tube36. Those portions of the insets' 39. and 40 which are in the bores in the head 38 are drilled and tapped and receive electrode screws 4I and 4'3 respectively. Fastened to the top of the screw trode screw 4i, while rotation of the head 44v raises or lowers the electrode screw 43. Terminals 49 and 58 are mounted on the sidesof.y the insets- 39 and 4!) respectively, the insets being insulated from each other, and thus the electrode 4I is electrically connected to the terminal 49 and the electrode 43l is electrically connected to` the terminal 50.

I provide a spring 5I engaging. the lever 2| and being held in place thereon by a projection 52v and reacting against a stud 53 projecting downwardly from the cover 25. This spring. forces the projection 23 downwardly whenever and as the plunger I8 rises; by reason of the location of the pivot stud 22: a slight upward movement of the plunger I 8 results in a large downward movement of the projection 23 with corresponding depression of the diaphragm 29.

Considering now the action of the mechanism,

assuming the top of the plunger I8 to be in engagement with the work-piece W which is being ground by a grinding wheel G, as the work-piece becomes smaller the plunger I8 rises under the influence of the spring i6. This results in downward movement of the diaphragm 29 which forces mercury out of the box 21 up the tube 34. The diameter of tube 34 is small while that of the box 21 is large, and this mechanism is the reverse of a hydraulic jack. Thus a very ne movement of the plunger I8 responsive to a slight reduction of the work-piece causes a considerable rise of the level of. the mercury 32 in the tube 34, until finally the mercury contacts the electrode 4I. As soon as the mercury contacts the electrode 4I, acircuit is completed from the terminal 49 to what may be termed the ground electrode 35 thus,l as disclosed in the aforesaid patent to Cole and Belden No. 1,911,552, to cause the in-feed mechanism of the slide carrying the grinding. wheel G to stop. Thereafter grinding continues by reason of the strain set up in the machine parts, but at a slower rate, and giving the work-pieceW its final and finishing cuts. Responsive to, this, the work-piece W is further reduced` in diameter, which causes a further rising of. the calipering plunger'rod I8, thus forcing more mercury out of the box 21- andv up in the tubes 34 and 3G, until nally the mercury-contacts-.the electrode 43, closing a circuit including terminalSIland the electrode 35, and, according tothe disclosure in the aforesaid Cole and Belden patent, energizing a solenoid which causes the slide carrying the grinding wheel G to retreat the grinding operation.

It will be noted that each electrode 4I and.43v

may be adjusted within precision limits. By merely unscrewing the plug I2 the plunger rod I8 may be'removed and thus for coarse adjustments different plunger rods. I8 may be used, it being convenient to have a plunger rod for each finished size of. work-piece being ground, particularly as calipering apparatus is used to bring. to a given size a. great number of workpieces. It should be noted that this calipering or sizing mechanism quickly resets itself when,- ever an oversized work-piece is placed in the grinding machine, as depression o-f the plunger rod I8 raises the projection 23, thus taking the pressure off the diaphragm 29 and immediately lowering the level of the mercury 32 in the tubes 34 and 36. By providing a tapered bore 31Y the amount of reduction of a work-piece measured. by a given angular movement of either head 44 or 41 varies with the position of the contact end of. the electrodes 4I and 43 in the bore 31. Thus for the iinest work it will be found convenient, by selectio-n of a particular plunger I8 or introducing more mercury into the box 28, or both, tolocate the electrodes 4I and 43 in the upper part of the bore 31. Where longer intervals are desired between cessation of in-feed and withdrawal of the wheel slide, however, the electrodes will be located in the lower part of the bore 31. Thus the sizing mechanism of the invention is highly universal.

By the use of mercury contacts, arcing is practically eliminated and accuracy insuredand Iv am` plifies it. In the claims I have used the expressions hydraulic and the like to designate apparatus actuated by the mo-vement of a conned liquid, since liquids other than mercury may be substituted, as all liquids are virtually uncompressible under ordinary pressures. While mercury presents specific advantages due to the fact that it is itself a good conductor of electricity, various expedients might be adopted to l0 permit the use of a non-conducting liquid in this connection.

It will thus be seen that there has been provided by this invention an apparatus in which the various objects hereinabove set forth, to-

gether with many thoroughly practical advantages, are successfully achieved. As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth, or shown in the accompanying drawing, is to be interpreted as illustrative and not in a limiting sense.

I claim:-

1. In a grinding machine, a plunger positioned to engage a work-piece being ground, a lever actuated by said plunger, a diaphragm actuated by the lever, a vessel filled with mercury in communication with and controlled by said diaphragm, a tube connected to said vessel, and an electrode in said tube, whereby reduction in size of the work-piece to a particular diameter forces mercury into contact with the electrode closing an electric circuit through the electrode.

2. In a grinding machine, a work calipering plunger, mechanical means to amplify the movement of said plunger, a chamber filled with mercury, a diaphragm on said chamber, connections between said mechanical means and said chamber, a tube connected to said chamber, a pair of electrodes in said tube, and adjustable means to adjust the effective po-sition of said electrodes.

3. In a grinding machine, a contacting member, a large chamber, a tube connected to said large chamber, mercury in said chamber and said tube, connections between said chamber and said work calipering member including a diaphragm whereby to: change the level of the mercury in the tube when the work calipering member is moved, and a pair of adjustable electrodes in said tube.

4. In a grinding machine, a work contacting member, a chamber filled with mercury, a diaphragm on said chamber, connections between said work contacting member and said diaphragm, a tube connected to said chamber, a tapered bore in said tube, and an adjustable electrode in` said tapered bore.

ARNOLD L. JOHNSON.

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