US2276757A - Laboratory milling machine - Google Patents

Description

\March 17, 1942. w. J. BAINES 2,276,757

LABORATORY MILLING MACHINE Filed June 2, 1938 4 Sheets-Sheet 2 m MMMMMMM March 17, 1942.

w. J. BAINES LABORATORY MILLING MACHINE Filed June 2, 1938 4 Sheets-Sheet 5 March 17, 1942. w. J. BAINES 2,276,757

LABORATORY MILLING MACHINE Filed June 2, 1958 4 Sheets-Sheet 4 mg m INVENTOR Patented Mar. 17, 1942 UNITED STATES PATENT- QFF I CE LABORATORY MILLING MACHINE Wilbert J. Baines, Pittsburgh, Pa.

Application June2, 1938; Serial vN0. 211,419

16 Claims.

My present invention relates to laboratory milling machines which are adapted to cut or produce samples from various metallic products in order that the samples may be analyzed and the composition of the products checked.

Insofar as I am aware, there has been very little done in connection with the production of special machines for securing metal samples from metallic products for analysis, and this despite the fact that there is a real need for a machine of this character. In most cases, samples have been chipped off by hand or procured by drilling or in some other haphazard manner, and hence the need for an effective machine for sampling metal products has not been satisfied. The difficulty with the more or less haphazard methods heretofore used lies in the fact that there is no assurance that typical, representative or identical samples can be secured, and hence even after analysis of such samples as have heretofore been taken from metal products, some doubt always remains as to the composition of such products and particularly. as to the homogeneity or uniformity of the same.

It is, accordingly, one of the objects of my present invention to produce a. laboratory mil-ling machine which is comparativly simple in construction, relatively inexpensive to manufacture, and which has a universality of use which adapts it to many kinds and shapes of metallic products.

Another object of my invention resides in a milling machine which is characterized by its adaptability to all sorts of metal products either initially or by the use of accessory appurtenances which are readily installed and removed at will.

A further object of my invention resides in a milling machine which is adapted to be either power driven or hand driven and which is characterized by a simple but sturdy construction which has a long life without loss of eificiency.

Other and further objects and advantages reside in the various combinations, sub-combinations, and details of construction hereinafter described and claimed, and in such other objects and advantages as will be understood by those skilled in this art.

In the accompanying drawings wherein I have illustrated practical embodiments of my invention:

Figure 1 is a side elevational view of a power driven milling machine in accordance with my present invention;

Fig. 2 is a side elevational view of a manually operated milling machine;

Fig. 3 is a .plan view of thewmillingmachine of Fig; .2;

Fig. 4lis atopaplan view of the power driven machine of. Fig. .1;

Fig. 5. isv a skeleton perspective View of the workinglparts of the powerdriven machine of Figs.:.1 and 4;

Fig. 6 is aview partly insection and partly in elevation taken on line VI-VI of Fig. 4;

Fig. '7 is..a side elevational view-on an enlarged scale of 1 certain of the structural details of the feeding mechanism of the power driven machine;

Fig. 8 is anendelevational view'partly in section looking from right to left in Fig. 7;

. Fig. 9 is a face View of a shearing disk forming. one of the accessories of my present machine;

Fig. .9ais amodifiedform of shearingdiskprovidedwith slots instead of the apertures of Fig.

Fig; .lOis a-view. similar to Fig. 9 but with =bushings disposed 1 therein Fig. 11 is a vertical, medial. section taken on line XIXI of Fig. .9;

Fig. 12 is a vertical, medial sectional View taken online X[IXII of Fig. 10;

Fig. 13 is an end view of one of the bushings of Fig. 10;

Fig. 14 is alongitudinal sectional view through the bushing of Fig. 13;

Fig. 15 is a rear elevational view of-a clamping chuck: forming. another accessory of my machine;

Fig. 16 is a longitudinal sectional View through the chuck of Fig. 15;

Fig. 17 is a vertical'sectional'view of a wire feeding. accessory partially shown in Fig. 2;

Fig. 18 is a fragmentary view similar to Fig. 17 Y but in which the shearing disk of Fig. 9 is shown in operative position;

Fig. 19 is an end elevational view ofa special clamping attachment usable either with the power driven machine of Fig. 1 or the manually driven machine of Fig. 2;

Fig. 20 is a side elevational view of the special clamping attachmentof Fig. 19;

Fig. 21 is a plan View of a modified wire feeding attachment applicable to my new milling machine;

Fig. 22 is a side elevational view of the parts of Fig. 21; and

r Fig. 23 is a longitudinal sectional view through the attachment of Fig. 21 to illustrate the construction thereof. I

Similar numerals designate corresponding parts throughout the various views.

Referring first to the power driven machine, a base (not shown) is provided which may be composed of any suitable material (preferably metal) and which may be bolted or otherwise secured to any suitable supporting surface. Angle irons H] are .secured as by bolts II to such base and to adjacent castings I2 by bolts or the like I3. Castings |2 are provided with ways M on which is adapted to slide the carriage designated as a whole by the numeral l5. Carriage I5 is provided with wearing bar inserts |6 bolted to the carriage by bolts l7; l4 and I6 slide on one another.

On the castings I2 is mounted a gear box l8 which has a removable top plate l9 and a removable end plate bolted at 2| to gear box I8. End plate 20 has a hollow circular projection 22 and a semi-circular projection 23 provided with a plug 24. This gear box I8 is provided with aligned openings I80. through which passes feed screw shaft 25, on one end of which is mounted a hand wheel 26 having a handle 21 and which is suitably secured to the shaft in any known or desired manner. This shaft 25 is threaded as indicated at 28 from the end with the hand wheel 26 to a point somewhat beyond gear box I8 from which point to its other end it is smooth and unthreaded except for a short distance at such other end Where it is again threaded as indicated by the numeral 29 (see Fig. '7 Screw shaft 25 also passes through a supporting bearing 30 which is provided with a smooth aperture therethrough so that the shaft may move longitudinally forward and back through such bearing. The bearing 30 also forms a part of the carriage l5, and the parts are so constructed and arranged that movement of shaft 25 effects sliding movement of carriage I5, as will be hereinafter more fully understood. This movement is imparted to the carriage by the shaft through the provision of a thrust bearing 3| abutting against the bearing 3|] just described and provided with a collar 32 into which fits one end of the spring 33 This spring 33 encircles shaft 25 at an unthreaded portion thereof, and the other end of the spring presses against and is partially received within the somewhat flaring bell-shaped end 34 of sleeve 35 which is suitably mounted on or secured to the said shaft 25. On the other side of the bearing 30 the threaded end of the shaft is provided with a locking disk assembly 36 which is threaded on portion 29 of shaft 25 and which is prevented from moving off the shaft by the lock nut 31. The locking disk assembly is shown as being provided with a recess or depression 38 at one portion in its periphery, and this recess is adapted to cooperate with the locking lever 39 pivotally mounted on the bearing 36, before described, by means of a fastening instrumentality such as a bolt 46, and this locking lever has a convex end portion 4| which, under appropriate conditions as will be hereinafter set forth, fits into the said recess 38 and locks the parts in position until the screw 25 is fed forward by worm wheel 43 a sufficient amount (distance A as indicated in Figs. 4 and 7) to advance locking disk 36 out of engagement with end portion 4| of lever 39. From the structure described it will be understood that by screwing and unscrewing disk 36 on the shaft end 29 the tension of spring 33 may be Varied to vary the amount of cut taken. This is because the advancement of screw 25 will, through pressure of spring 33, advance carriage l5 along with screw 25 until resistance of the work on the cutter overcomes the pressure of spring 33, whereupon screw 25 will advance the head of carriage |5 to move disk 36 through the distance A to cause lever 39 to unlock from 36 on the occurrence of which shaft 25 will rotate without further forward motion.

Within gear box |8 said screw shaft 25 is provided with a worm wheel 42 which has a collar 43 and thrust bearing 43a for the purpose of maintaining the gear in centrally disposed position in said gear box, as will be clearly apparent from Fig. 4 in particular. This worm wheel 42 meshes with a worm 44 disposed On a transverse shaft 45 at one end of which is provided a helical gear 46 meshing with a worm 4'! disposed on stub shaft 48 (operating in bearings 48a) to the other end of which is secured a pulley or the like 49, the fastening being accomplished by means of a set screw 5|) passing through a hub 5| provided on such pulley. The numeral 52 indicates a fragment of a belt or other driving member which passes around the pulley 49 and which is connected to a source of power such as the pulley of a suitable electric motor (not shown) or other motivating means.

The other end of transverse shaft 45 is provided with a spiral gear 53 which meshes with another spiral gear 54 which is keyed at 55 to the longitudinal shaft 56 which extends parallel to the feed screw shaft 25. One end of longitudinal shaft 56 is provided with a worm 51 and I this meshes with a worm wheel 58 mounted on the end of a transverse shaft 59 to which a spiral cutter 60 is intermediately keyed at 6|. The last named shaft is mounted in suitable bearings indicated by the numerals 6| and 62, and a bushing, collar or the like 63 is provided on the end of the shaft opposite worm wheel 53 to keep the shaft in proper relationship and thus to maintain the milling cutter centered with respect to the clamping assembly designated as a whole by the numeral 64. It will be noted from 'Figs. 4 and 5 in particular that the bearings 6|,

62 and shaft 59 form a part of and move with the slidable carriage I5. It will be noted that the machine is provided with oil cups 65 at various points in order to insure smooth operation and to avoid unnecessary wear of the metal to metal contacts.

The clamping assembly 64 is made up of two U-shaped metal members 66 spaced apart and bolted to the angle irons l0 of the machine at 61, it being noted that the base is provided with a plurality of linearly spaced apertures 68 in order that the clamping assembly may be bolted in place in a variety of positions longitudinally of the machine as a whole. The U-shaped members 66 are also provided with aligned apertures 69 for the reception of bolts H1 in order that the U-shaped members may be tightened upon the work to be sampled. The work piece, by way of example, only, is shown as a rod While the lower portions of the U-shaped members are fixed as to their position, the top portions are susceptible of movement toward or away from each other to a sufiicient extent to enable work pieces of various sizes, shapes, and configurations to be clamped firmly in position during the time that it is desired to take samples therefrom for analysis or other purposes.

It will be noted that when end plate 26 is in place the end of shaft 45 where gear 46 is 1ocated turns in circular projection 22 which-acts as an end bearing and that thesemi-circular projection 23'allows proper operating space and conditionsfor gear 41 so that gears 46 and 4-! may be run in a suitable lubricant. Web I81) of gear box- 18 dividesthe gear boxinto chambers or compartments not only to reinforce: and strengthen such gear. box but to make the application and utilization of lubricant economical and efficient. It will further be observed that members 6|, 62-are joined into a yoke-shapedv casting which merges with and forms apart of the carriage I5.

In operating the power driven machine provided with the parts thus far described, hand wheel 26 is rotated in such direction (er a, counterclockwise) as to retract carriage I and cutter 60. Then the work piece H to be sampled is clamped in the clamping assembly 64 in a manner which w-ill-be-understood from the structural nature of the parts involved. Next the hand wheel is rotated in the opposite direction (e. g., clockwise) to advance the carriage l5 and, at the same time, the milling cutter cihuntil that cutter abuts the work or piece to be sampled (Figs. 1 and 4) whereupon forward movement of the carriage ceases. Next lever 39 is lowered to horizontal position from its normally angular position (see Fig. 8) in such manner as to cause the end 4| of the lever to engage the recess 38 in looking disk assembly 36; Then the pulley 49 is caused to rotateand this, operating through the shafts and gears above described, causes rotation of the milling cutter against the work piece to be sampled, thus removing material therefrom which can be collected in a suitable container or the like placed in a position to catch the chips. chips from the work piece, the carriage advances a small but definite additional amount represented by the distance A between the short vertical lines in Figs. 4 and 7. Now then, as cutting of the sample,- proceeds and as the said screw shaft 25 advances the small additional amount so that the cutter can remove a definite amount of material from the work piece, this causes a gradual compression of spring 33 which compression causes the cutter to be fed into the work piece until the parts reach the positions of Fig. 7, whereupon the locking disk assembly snaps back to the position shown in Fig. 4, it having advanced from that position to the position of Fig. '7 during the aforesaid additional forward movement of the said feed screw during the cutting operation. As locking disk assembly 36 snaps back from the position of Fig. 7 to the position of Fig. 4 (the parts becoming unlocked in the position shown in 'Fig. 7) the machine is then in condition to take another cut or sample from the work piece, but before the additional cut is made the position of the work piece in the clamping assembly is changed so that a sample is taken from the opposite side or from other portions of the work piece, and this is continued until sufficient samples have been accumulated to insure that an analysis thereof will properly represent the composition of the work piece as a whole. If desired, the chips taken in any one cutting operation may be separately collected and analyzed where it is desired to compare the analyses of different portions of the work piece. Of course, when locking disk assembly 36 moves from the position of Fig. 4 to the position of Fig. 7, the locking lever is as stated at such time automatically released; and

As the milling cutter removes when the locking disk assembly snaps back under the influence-ofspring- 33, then the locking lever re-locks the'assembly, the convex portion of the ticular the sampling of a metal rod placed in a vertical position, it is to be understood that the work piece may be of any size, shape, or other characteristic within thelimitations of the clamping assembly which, however, is so arranged that it can take care of a considerable variety of work pieces."

In the manually operated form of the machine illustrated in Figs. 2- and 3, the construction there shown is generally the same as the power driven machine just described, as will be .appreciated from the use of the same numerals thereon followed by a prime mark. In the hand operated machine, however, the transverse shaft45 is somewhat elongated so that it projects through the cover plate 20'. On this projecting end a manually rotatable fly wheel 12 having handle it is secured, and if so desired a similar fly wheel may be mounted on the other end of the shaft which may likewise be lengthenedandis so shown at 45"to project through the gear box 18'. It will be noted also in connection with Figs. 2 and 3 that there is no locking lever provided as in the case of the power driven machine, as I find that this is not required in all cases and may be omitted depending upon the particular type of work piece tobe sampled and upon the necessity for insuring a cut into the work piece of a certain definite depth.

Likewise, the clamping assembly 64- of Figs. 2 and 3 is constructed somewhat differently than in the power driven machine, but it is to be understood that the clamping assembly now to be described'may equally well be used with the power driven machine if so desired or preferred. Between the U-shaped elements 66' of the clamping assembly 64" of Figs. 2 and 3, a rectangular metal insert 74 is positioned which is provided with a boss 15 on its rearward edge. This boss, as well as the insert member 14 itself, is provided with a threaded opening H5 therethrough and directly opposite in the front portion. of the insert an aligned registering aperture 11 is formed, all these apertures being in line with the milling cutter 63 which is mounted on'the carriage iii of the machine as previously de scribed. Above the aperture H a threaded opening 18 is formed, the purpose of which will be hereinafter explained. In the aperture 11 a headed bushing 19 is inserted in the position shown in Fig. 1'7, and this bushing has a longi tudinal bore which is of sufficient size to allow a wire 8| or other member to be sampled to be passed into contact with the milling cutter 60. The arrangement is such that the wire 8| is gradually fed to and against the milling cutter for the purpose of removing metal from the end thereof.

The feeding means is made up of an exteriorly threaded, internally bored shaft 82, on the outer end of which is mounted an operating wheel 83 having a handle 84, wheel 83 having an aperture 85 therethrough aligned with the bore of the shaft 82. A chuck 36 is provided on the end of the threaded shaft and is of the familiar construction known as a drill chuck, This is composed of a generally cylindrical body portion 8! having a threaded bore 83 there-through and a somewhat tapering forward portion 88 within which are disposed the holding or gripping elements 90 which are connected together under spring action so that they are capable of radial inward or outward movement in response to the size of the member or piece to be held thereby. Thus, to feed the wire 8I of Fig. 17 into cutting contact with the milling cutter 66' the operating wheel 83 is turned in such direction as to advance the threaded shaft 82, and then when a sufficient sample has been removed by the cutter and collected for analysis the operating handle is turned in the opposite direction and the wire is withdrawn. The arrangement is such that wires of various sizes can be sampled in a simple and effective manner.

It will be noted further that four recesses 9| are provided on the inner surface of the insert I4, and .by comparing this figure with Fig. 3, for example, it will be understood that these recesses make it possible to pass bolts III through the entire clamping assembly and to clamp the insert firmly in position between the U-shaped clamping elements 66. It will be understood that prior to feeding wire 8| to cutter 60, carriage I is advanced as above explained anent carriage I5 until cutter 69 is in proper position. This is secured by providing an adjustable stop 65a on one of members 56. A boss 66b is traversed by a screw 650 which is pre-positioned to abut against member BI (see Fig. 3).

It will be observed from Fig. 18 that the shearing disk 92 of Fig. 9 may be assembled onto the insert I4 by passing a bolt 93 through the central opening 94 of the shearing disk and through the opening 18 in the insert. In such position the shearing disk will have one of its twelve (12) openings 95 in alignment with the aperture IT in the insert; and, depending upon the size of the wire or other element to be sampled, a bushing 95 of required bore is inserted through the lowermost opening 95 of the shearing disk 92 and into the opening 11 of the insert. This not only provides a free unobstructed path of travel for the wire 9! of Fig. 18 but also serves to lock the shearing disk temporarily in position. It forms a part of my invention to provide each of the openings 95 of shearing disk 92 with a bushing 98 having a different sized bore 96a so that when it is desired to sample a wire or rod of certain diameter the shearing disk 92 can be readily rotated to such position that the bushing with the right sized bore will be in the lowermost position, as it is desired to have the wire or rod pass through a bushing which has a bore substantially equal to but not materially greater than the diameter of the wire or rods as this not only serves to insure accurate positioning and feeding of the wire or rod but prevents slippage, the cutting of the samples at a diflicult angle, and the avoidance of undesirable results which may be caused by wobbling of the wire or rod during the cutting operation. These bushings may either be of the headed type 96 as shown in Fig, 18 or they may .be plain, i. e., unheaded as shown at 95 in Figs. 12 to 14 inclusive. In each case the bushing is secured in place by a set screw 98.

It is, however, within the purview of my invention to provide apertures in the shearing disk which themselves vary in their size, although I have found that it is more practical and economical from a production point of view to provide shearing disk openings all of one size and to obtain the bore variations by the use of the bushings as above explained. As shown in Fig.

9a, shearing disk 92a is provided with slots 95a of various sizes radially disposed around central opening 94. Metal articles or products within the shape and size limitations of any of these slots can be fed and sampled as will be understood from the preceding description.

In Figs. 19 and 20 I have illustrated a clamping accessory which makes it possible to sample or cut wires or rods of various sizes and shapes in another manner. In these figures I provide two jaw elements 99 which are adapted to be received between the U-shaped clamping elements 66 or 66 of the clamping assemblies 64 and 64 in such manner that the ends of the U-shaped elements rest within the cut away portions I00 in the jaw elements which are also provided with the aligned apertures IOI which are so positioned as to make the same register with the openings I02 in the clamping assembly 64', for example, and through which bolts I03 pass.

These jaw elements are so configured that they have no top or bottom, 1. e., they are the same at both ends and therefore they can be assembled either in the position shown in Fig. 19 or in the inverted position from that shown in Fig. 19, depending upon whether it is desired to have the larger diamond shaped opening I04 or the smaller opening I05 in wire or rod receiving position. A wire I06 is shown passing through the larger diamond shaped opening I04 in Figs. 19 and 20, and while round wire or rod can be satisfactorily used with this accessory, it is particularly designed for material of rhomboidal section. v

The use and operation of the accessories shown in Figs. 19 and 20 will be clearly understood from the foregoing, and it is pointed out that such may be used either with a feeding assembly such as that shown in Fig. 17 or a hand feeding may be utilized. I also wish to point out that for wire or rod I prefer a milling cutter which has 24 teeth preferably arranged as shown in Fig. 5, and that for larger work or work of a heavier nature I prefer to use a milling cutter of the same character but which has only 14 teeth. The milling cutter itself must be of strong and sturdy construction, but since such cutters are, per se, well known, I may use any suitable one now available.

In Figs. 21 to 23 inclusive I have illustrated a wire or rod feeding accessory which partakes of an automatic character being operated when milling cutter 60' is rotated, although it is to be understood that this accessory may be used equally well with the power driven machine above described.

Between clamping elements 66 of clamp assembly 64 a generally rectangular member or casting I01 of an elongated character is secured. In one end casting I01 is provided with an aperture I08 in which hollow bushing I09 is adapted to be inserted as shown. At the other end casting I0! is provided with a threaded opening III] and with a similar opening I I I in transverse web H2. An exteriorly threaded internally bored shaft H3 passes through openings H0 and III when the shaft is turned. Shaft H3 is also provided with a groove H4, the depth of which tapers off toward its ends as is clearly apparent from Fig. 23. Set-screws II5 pass transversely through one side of the shaft I I3 to hold rod H6 or other work piece of similar shape from moving longitudinally relative to shaft II3'. A hand wheel H'If having a handle H8 is secured to one end of shaft H3 and this hand wheel has a hollow hubor center so that rod I It can pass therethrough as shown, the rod being fed through the bore of bushing I09 during feeding action as hereinafter set forth.

A worm wheel Shaving a threaded-bore is threadedly mounted .onshaft H3 between web H2 .and the adjacent end ofthe casting IN, a thrust bearing IIZ being mounted on one side of worm wheel II9 anda washer or collar I2I being mounted on the other-side.

Worm wheel H9 meshes with worm 122, the

journals I23 of which rotate in bearings I24, one of the journals beingsomewhat extended and having a bevel gear I25 mounted thereon. A bevel gear I26 meshes with bevel gear I25'and is mounted on the end of shaft I2! which is,in effect, a prolongation of shaft '56" beyond the worm 57', the latter meshing with worm wheel 58 as previously described. Worm wheel' 58' and .cutter 68 are both mounted on shaft 5% (see Fig. 3).

a -A pin or thelike I28 having a thinnedortapered lower end passes through the-casting I01, as shown, and is adapted to fit into groove I I4 in shaft 1 I3.

H3 from turning but it-may bezraised sufliciently to disengage from groove I-I4and to permit shaft H3 to turn freely. A'suitable stop 66a is provided either on one of the clamping elements 66 or on casting I81 as will be understood from stop 66a (Fig. 3) above described. The bevel gears I25, I23 are mounted in an L-shaped bracket or casting I29 on one side of casting Ill! and an opposite piece I30 is held on the other side by screws, bolts, or thelike I3I.

In using the attachment orsaccessory of. Figs. 21 to 23 inclusive, the wire or rod H6 is threaded through shaft H3 and through bushing I09 and held in place by tightening either or both setscrews H5, pin I '23 being at-the time unengaged with groove IM. Then hand wheel II! is 'rotated to advance-shaft H3 and wire or rod II 6 sufiicientto cause the end of M5 to abut milling cutter 60' (or (iii) which-has previously been advanced as 'faras-permitted by" stop 66a as will be understood from what' has :preceded. Then pin I28 is engaged in groove-H4 and upon rotation of cutter 80 worm-wheel H9 vis -:caused'to turn, and, being threadedon shaft I I3, moves the shaft longitudinally, thus gradually feeding,

wire to cutterfiil' as long-as'cutting or sampling is desired or required. Thus this accessory or attachment is driven as and when cutter B9 (or 89) is rotated.

A milling machine of anyoftheforms above described -may be-used toxobtain samples from many different kinds of workpieces or material. Among thesemay be enumerated rods,- wire, sheets, blocks, plates, small beams and 'angle irons, as well as manyother fabricated shapes which will suggest themselvesto those skilled in this art or which it may be-desired to sample for analysis purposes. Another advantage of my machine is that it is portable, and hence it is not always necessary to bring the material to be sampled to the laboratory since the machine may be transported to any given fabricating or erecting operation and can be so handled'as to take small chips or samples from girders, beams,

plates, and other pieces already installed as in a building, bridge, or other construction'project. Since the amount of-material removed by my machine for sampling purposes can be maintained extremely smaIL'tno-harmfuI result occurs from using the machine in connection With metal In such position it'prevents shaft H pieces already installed in a structure and which have'been designed for given stress conditions.

It is, therefore, within the scope of my invention to make various additions, omissions, substitutions, and modifications without departing from the spirit and principles herein set forth;

the scopeof the invention is apparent from the appended claims.

What I claim is new and desire Letters Patent is:

l. A laboratory milling-machine comprising a slidable carriage, a rotatable milling cutter mounted on said carriage, a clamp assembly adapted to hold a work piece, mechanism for to secure by advancing said carriage and cutter untilthejlatrotating said cutter and for furtheradwancing it to :a predetermined amount to remove material from said work piece.

2.'A laboratory milling-machine comprising a rotary milling cutter, a clamp'assembly adapted to hold a work piece to be acted upon by said cutter, means for slidably advancing said cutter into a position in which it abuts the work piece and means'for rotating said cutter and for advancing it a predetermined furthera-mount as it cuts into said workpiece.

3. A laboratory milling machine as set forth in claim 2 wherein means is provided for automatically retracting said cutter after it has advanced the predetermined'distance during its rotation.

4. A laboratorymilling machine comprising a pair of slide ways, a carriage mounted for movement therealong, a feed screw shaft for effecting forward and-back sliding movement of said carriage on said slide ways, a yoke-shaped portion extending from said carriage, a milling cutter rotatably mounted in said yoke-shaped portion and means forclamping a work piecerin cutting relationship with said cutter, ;the construction and arrangement being such --that said carriage and hence-said cutter are advanced by means of said feed screw shaft into such position that said cutter abuts said work piece,,a-nd;means for ro- 'tating said cutter for'removing material from said work piece.

5. A laboratory milling machine comprising a pair of slide-ways, a carriage mounted for movement therealong, a feed screw shaft for effecting forward and-back sliding movement of said carriage on said slide Ways, a :yokeishaped portion. extending frorn'said carriage, a milling cutter rotatably mounted in said yoke-shaped portion, means for clamping a workpiece in cutting relationship with said cutter and means for rotating said cutter, the construction and arrangement being such that said carriage and hencesaid I cutter are advanced by means of said feed screw shaft into such position that saidcutter abuts said work piece and said'cutter is rotatedbysaid rotating means for removing material-from said work piecesaid feed screw shaft being provided witha locking assembly such thatzwhen said cutteris advanced into abutment with said work piece further movement of saidcarriage and said cutter due to feed screw shaft movement isprevented and said locking assembly automatically causing retraction of said cutter after'the same has advanced into and cut a predetermined amount of material from said workpiece.

6. A laboratory millingmachine as set forth in claim lwherein means is providedfor-retracting said milling cutter after it has removed a predetermined amount .of material from said a feed screw shaft, a bearing through which the same passes, a locking disk assembly on the cutter side of said bearing, a lock nut for preventing said locking disk assembly from moving off said shaft, a locking element adapted to cooperate with said locking disk assembly, a spring on the other side of said bearing and encircling said shaft and means for maintaining said spring in position around said shaft and for enabling said spring to effect automatic retraction of said locking disk assembly when said feed screw shaft has moved sufficiently through said bearing to cause said locking member to move out of locking engagement with said locking disk assembly.

'7. A laboratory milling machine comprising a slidable carriage, a bearing mounted on and forming a part of said carriage, a feed screw shaft extending through said bearing, a yokeshaped extension on said carriage, a transverse shaft rotatably mounted in said yoke-shaped extension, a rotary milling cutter intermediately keyed to said transverse shaft, a worm wheel at one end of such shaft, a worm meshing with said first worm wheel, a longitudinal shaft carrying said worm, a first spiral gear keyed to said longitudinal shaft, a second spiral gear meshing with said first spiral gear, a second transverse shaft carrying said second spiral gear, a worm carried by said second transverse shaft intermediate the ends thereof, a gear alsocarried by said second transverse shaft, a worm meshing with said last gear, a stub shaft carrying said last worm, a worm wheel mounted intermediately on said feed screw shaft and meshing with said worm on said second transverse shaft, means for turning said feed screw shaft, means for turning said stub shaft, means mounted on said feed screw shaft adjacent said carriage bearing for automatically retracting said carriage upon a predetermined extent of movement of said milling cutter and means for clamping a metallic work piece in operative association with said milling cutter so that said milling cutter removes material from said work piece for analysis purposes.

8. A power driven automatic laboratory milling machine of the character described comprising means for holding a metal work piece to be sampled, a rotary milling cutter adapted to remove material from said work piece, manually operated and controlled means for advancing said cutter into contact with said work piece and power driven and controlled means for rotating said cutter against said work piece and for advancing said cutter a predetermined further amount.

9. A laboratory milling machine which is adapted to remove metal for sampling and analysis purposes from structural metal members already installed in a structure which comprises the combination of a milling cutter capable of being advanced and retracted and capable of being rotated for cutting purposes, means for advancing said cutter into contact with the structural member to be sampled and means for rotating said cutter when so advanced and for advancing the cutter a small incremental amount during its cutting operation whereby a relatively small but predetermined amount of metal may be produced from said structural member for analysis purposes without appreciably damaging the structural member itself.

10. In a laboratory milling machine of the w work piece and wherein said last means includes character described, a slidable carriage, a bearing forming part of said carriage, a feed screw shaft passing through said bearing, a locking disk assembly mounted on said shaft on one side of said bearing, a lock nut for maintaining said locking disk assembly on said shaft, a locking lever adapted to have operative engagement with said looking disk assembly, a spring encircling said shaft on the opposite side of said bearing, means for holding said spring around said shaft and a thrust bearing between said spring holding means and said bearing whereby movement of said shaft through said bearing causes said locking disk assembly to move out of locking engagement with said locking lever, whereupon said locking disk assembly is retracted into locking engagement with said locking lever under the influence of said spring.

11. In a laboratory milling machine of the character described, a generally rectangular clamp insert provided with a boss and having aligned apertures therethrough, a bored shaft extending through certain of said apertures, a chuck on one end of such shaft and a hand wheel on the other end of said shaft, a hollow bushing in said insert in alignment with said shaft and chuck and said insert being provided with semicircular recesses in the inner peripheral corners thereof, whereby a wire work piece may be fed through said insert and said insert may be secured to the clamping assembly of said milling machine.

12. In a laboratory milling machine of the character described, a rectangular metal clamp insert having aligned apertures passing horizontally therethrough and a threaded aperture superjacent one of said previously mentioned openings, a shearing disk secured to one face of said insert by a bolt passing through the disk and through the threaded aperture aforesaid, said shearing disk being provided with a plurality of circumferentially spaced apertures in each of which a hollow bushing is secured, said shearing disk being rotatable with respect to said insert and each of said bushings being selectively engageable with that insert opening subjacent the threaded aperture, each bushing having a bore different in diameter from the other bushings so that a work piece of any size within the limits of the bushing bore sizes may be fed through said insert and through that bushing which occupies the lowermost position in the shearing disk at any given time.

13. In a laboratory milling machine of the character described, a shearing disk comprising a solid metal member provided with a central aperture and with a plurality of circumferentially spaced apertures radially equi-distant from the central aperture, a plurality of radial openings in said disk extending from the radially outermost point of each of the circumferentially spaced openings and a hollow bushing disposed in each such circumferential aperture and secured therein by a fastening instrumentality passing through said radial openings, each of said hollow bushings having a bore of a different inside diameter.

14. A laboratory milling machine of the character described comprising means for holding a work piece in position to be sampled, a milling cutter for removing material from said work piece, means for linearly moving said work piece and cutter relative to each other to bring them into abutment, means for rotating said cutter for cutting purposes and means actuated by the cutmeans for clamping a metallic work piece to be sampled for analysis, a rotatable milling cutter adapted to remove a sample of material from such work piece, means for sliding said cutter linearly into abutment with said clamped work piece, means for rotating said cutter in contact with said work piece and while further advancing v said cutter as it removes material from such work piece, and means for automatically retracting said cutter after it has removed a predetermined amount of material from said work piece.

WILBERT J. BAINES.

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