US2562841A - Mining machine head - Google Patents

Description

July 31, 1951 c. E. COMPTON MINING MACHINE. HEAD Original Filed April 19, 1950 3 Sheets-Sheet 1 INVENTOR CHARLES E. COMPTON July 31; 1951 c. E. COMPTON MINING MACHINE HEAD Original Filed April 19, 1950 5 Sheets-Sheet 2 INVENTOR C HARLES E. COMPTON y 31, 1951 c. E. COMPTON 2,562,841

MINING MACHINE HEAD Original Filed April 19, 1950 3 Sheets Sheet 5 J INVENTOR Patented July 31, 1951 MINING MACHINE HEAD Charles E. Compton, Shinnston, W. Va.

Continuation of application Serial No. April 19, 1950. This application July Serial No. 178,206

I 12 Claim.

This invention relates to mining machine heads, especially heads which are advanceable into a working face or body of material to remove material therefrom. This application is a continuation of my copending application Serial No. 156,867, filed April 19, 1950, which in turn is in part a continuation of my copending application Serial No. 104,445, filed July 13, 1949, both applications now being abandoned.

The invention is concerned with mining or tunneling, depending upon whether the purpose is to recover the removed material or to form a tunnel. I use the word "mining herein as a word of broad definition comprehending removal of material whether the purpose is to recover the material or to form a tunnel.

Various types of mining machines have been proposed which are adapted to be advanced toward a working face and which have heads designed to enter the face and remove material therefrom, one use of such machines is in the mining of coal although they may be otherwise used. For purposes of explanation and illustration I shall describe my invention in connection with the mining of coal.

Machines of the type above referred to which have heretofore been proposed have not been fully satisfactory for the mining of coal. Generally they have had one or both of two disadvantages. A primary disadvantage has been the breaking up of the coal into undesirably small pieces. Another disadvantage has been the complexity of the machine and the consequent high cost per ton of mining with it. Many machines designed for the mining of coal have had both of the disadvantages mentioned. The problem is one of long standing.

I provide a mining machine head which may be applied to any suitable machine for rotating the head and advancing it into a face, which head is of rugged, simple and foolproof construction yet at the same time removes coal without breaking it up into undesirably small pieces and delivers the coal with unprecedented economy. My head preferably comprises a rotatable and advanceable cutter element having a material passage therethrough extending generally parallel to the axis of rotation and having periphery cutting means mounted thereon at the forward end thereof disposed to cut a generally cylindrical kerf in a body of material upon rotation and advancement of the cutter element. My cutter element may take the form of a hollow cylinder open at both ends having periphery cutting means at its forward end which is adapted 2 to enter a face and sever therefrom a generally cylindrical mass which lies within the cylinder. Such a cylinder is not in itself new.

I combine with the cutter element other elements so that the combination brings. about a basically new operation. I provide means for moving rearwardly within the cutter element the material of the generally cylindrical mass (e. g., coal) at a speed such as to prevent clogging in the cutting zone and without breaking up the material into small pieces. To most effectively accomplish that result the means for moving the material rearwardly within the cutter element, here for example considered as being in the form of a hollow cylinder as above described, should at least the portion thereof disposed at the rear or delivery end of the cylinder have a diameter substantially equal to the inside diameter of the cylinder. The cylinder may have a diameter of the order of live or six feet, and with such a head I can regularly recover from the Pittsburgh seam in the west Virginia fields lumps of coal weighing to 300 pounds.

I provide as a part of the head a ribbed breaker which is preferably of reduced diameter at its forward end or nose. The breaker has outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardiy and circumferentially and in operation of the head performs two distinct functions. The nose of the breaker enters the material being mined and cooperates with the cylinder in cracking the material without breaking it up into small pieces. As the head rotates and advances the breaker also acts as a conveyor, pushing the fractured coal rearwardly within and finally out of the cylinder. Adjacent convolutions of the conveyor are spaced apart to provide space therebetween of materially greater crosssectional area than the rib means.

The breaker is preferably coaxial with the cutter element and connected therewith and preferably has inner cutting means mounted on the forward end thereof. The breaker is preferably small enough at its forward end to enter the opening formed by the inner cutting means but wider than that opening at its rearward end. The breaker at a zone not substantially in advance of the periphery cutting means is preferably of a width approximating that of the inner cutting means. The nose of the breaker is preferably within the head and may be behind the forward end of the cylinder when the cutter element is in the form of a hollow cylinder. The breaker is desirably within and connected with the cylinder coaxial with the cylinder. It is normally entirely within the cylinder. In a head of the size above mentioned the nose of the screw may follow the forward end of the cylinder by perhaps 12 to 18 inches. The breaker enters the opening formed by the inner cutting means and causes the material to crack along irregular although somewhat radial lines outwardly toward the inner surface of the cylinder. At the same time the rotating and advancing breaker works its way into the fractured material and propels it rearwardly without breaking it up into small pieces. The forward extremity of the breaker should be behind the forward ends of the cutting means at the forward end of the cylinder. The inner cutting means may be behind the periphery cutting means or in substantially the same transverse plane therewith or on occasion somewhat in front of the periphery cutting means.

Other details, objects and advantages of the invention will become apparent as the following description of certain present preferred embodiments thereof proceeds.

In the accompanying drawings I have shown certain present preferred embodiments of the invention in which Figure 1 is a perspective view of a mining machine head;

Figure 2 is a front view of the head shown in Figure 1;

Figure 3 is a view similar to Figure 1 of a different and presently preferred form of mining machine head;

Figure 4 is a view similar to Figure 2 of the head shown in Figure 3;

Figure 5 is an axial cross-sectional view of the head shown in Figures 1 and 2 but with the inner cutting means and breaker; shown in elevation; and

Figure 6 is an axial crosssectional view of the head shown in Figures 3 and 4 but with the inner cutting means and breaker shown in elevation.

Referring now more particularly to Figures 1, 2 and 5, I provide a shaft I mounted for rotation and advancement. The means for rotating and advancing the shaft may be any suitable means for the purpose as known in the art and may be connected with the shaft adjacent its rear end which is not shown in Figure l but is to the right of the portion of the shaft which appears in that figure. Since the invention of the present application is concerned only with the head and not with the structure of the machine and since machines fcr advancing and rotating heads into working faces are old and known to those skilled in the art it is unnecessary to show any specific means for advancing and rotating the head. Those skilled in the art will understand that the head is suitably supported and aimed at the face to be penetrated.

The shaft 2 is preferably of substantial diameter, perhaps 12 to 18 inches, and may be in the form of a hollow pipe. Applied to the shaft 2, as, for example, by welding, is a screw designated generally by reference numeral 3 and having a rear portion 4 of relatively great diameter and a tapered nose portion 5. The front end of the shaft 2 may be tapered toward a point as shown at B, the tapered nose portion 5 of the screw 3 being an'outwardly projecting rid disposed about the reduced shaft end. The tapered shaft end I and the rib 5 form a breaker. A cutting tool I,

hereinafter called the inner cutting means, is

applied to the nose of the shaft and screw, 1. e., to the front end of the breaker, the shaft, screw and cutting tool all being coaxial.

Disposed about the portions 5 and ll of the screw and the shaft and the tool I is a cutter element 8 having a material passage therethrough extending generally parallel to the axis of the shaft 2, which is the axis of rotation and advancement of the cutter element 8, and having periphery cutting means in the form of cutters 9 and Ill mounted thereon at the forward end thereof disposed to cut a generally cylindrical kerf in a body of material upon rotation and advancement of the cutter element. The cutter element 8 shown takes the form of a cylinder arranged coaxial with the shaft and screw. The cylinder may have a diameter of perhaps five or six feet and may have a length of perhaps six feet. The internal diameter of the cylinder 8 is preferably substantially equal to the diameter of the portion 4 of the screw and it is ordinarily preferable to fasten the screw to the cylinder; in

Figures 1, 2 and 5 the periphery of the screw is welded to the inside Of the cylinder throughout a suiflcient length of the screw to insure a permanent connection under operating conditions; thus the shaft, screw and cylinder are all coaxial and unitary. In any event it is desirable that at least a portion of the screw have a diameter approximating the inside diameter of the cylinder which carries the cutting means whereby to obtain maximum material cutting and removing efllciency.

The periphery cutting means or cutters 9 and III are mounted on the cylinder at its forward end and project from the forward end of the cylinder as shown in Figures 1, 2 and 5 and additional cutters H are fastened to the inside of the cylinder and lie substantially against its inside surface somewhat rearwardly of its forward end. A spiral projection I2 is provided on the outside of the cylinder for conveying rearwardly along the outside of the cylinder as the cylinder rotates and advances small particles cut from the face which do not find their way to the inside of the cylinder. Such spiral projection obviates the collecting and jamming of small cuttings against the cylinder and the consequent tendency to bind the cylinder. By removing such small cuttings or particles the cylinder works relatively freely and the power required for its operation is much less than were the spiral projection not employed. The spiral projection I! may be a double lead spiral, i. e., it may consist of two spirals starting from the forward end of the cylinder apart and having the same pitch.

The cutters 9, HI and II have cutting faces which cut into the coal as the cylinder rotates and advances. The cutters may have a radial dimension substantially equal to the thickness of the material of the cylinder and the cutters 9 and Ill may project from the cylinder wall in axial alignment therewith, although I prefer to have some of the cutters, i. e., the cutters 9, projecting in the radial direction from the cylinder so that their radially outside surfaces lie approximately in a cylinder defined by the radially outside surface of the outside spiral projection II. For example, alternate cutters 9 and Ill circumferentially of the cylinder may have their radially outside surfaces (a) approximately in the cylinder defined by the outside surface of the rotatable and advanceable hollow cylinder and (b) projecting in the radial direction from the rotatable and advanceable hollow cylinder so that their radially outside surfaces lie approximately in a cylinder defined by the radially outside surface of the outside spiral projection II. The cutters II are optional and may be used or not as desired. When they are used they somewhat increase the cutting efficiency but may result in slightly reducing the size of the lumps of coal recovered.

The tapered nose portion 5 of the screw I forms a spiral rib or conveyor of reduced diameter relatively to the portion 4 which recreases to the full inside diameter of the cylinder and the full diameter of the position 4 at a portion of the screw which lies within the cylinder and the pitch of the rib 5 also preferably increases so that its conveying efficiency increases rapidly from its nose rearwardly, causing the coal to be somewhat accelerated in its rearward movement. This obviates clogging in the cutting zone, in turn considerably contributing to the recovery of large lumps as above mentioned. The coal is not crowded up and ground together but has free space into which to move in being propelled to the rear by the screw. The screw propels the coal out of the rear end of the cylinder and if the cylinder is driven into the face a distance greater than its length the screw projecting rearwardly from the cylinder cooperates with the cylindrical bore formed in the face to deliver the coal rearwardly therethrough.

Thus the breaker performs a twofold function of entering and cracking the coal at is reduced forward end and conveying the coal rearwardly at the portion thereof behind the forward end.

The screw acts continuously on the coal so that the coal is cracked and pushed rearwardly with great force but without great violence. The cracking of the coal into large lumps is contributed to by the fact that the breaker consisting of the tapered forward end 6 of the shaft 2 and the spiral rib 5 is at a zone not sub stantially in advance of the noses of the cutters 9 and ill of a width approximately that of the inner cutter 1 so that the breaker will not act on the coal substantially in advance of the periphery cutting means. In the form of Figures 1, 2 and 5 the periphery cutters 9 and Ill lead the breaker in its advance into the face so when the breaker acts on the coal that coal has already been severed from the face by the periphery cutting means; the nose of the breaker is shown as being disposed rearwardly of the forward end of the cylinder 8 a distance of the order of 12 to 18 inches.

The breaker rib 5 forms a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially. Adjacent convolutions of the conveyor are spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib. The passage space in the breaker preferably, as shown in Figures 1 and 5, increases in cross-sectional area in the direction from the forward end toward the rearward end of the breaker. This is accomplished by divergence of adjacent convolutions of the rib means 5 from the forward end toward the rearward end of the breaker.

After the forward end of the cylinder has penetrated the face to some extent the tool I cuts into the mass of coal severed from the face and lying within the cylinder. Following the tool 1 comes the reduced shaft end 6 and the portion 5 of the screw 3 which enters the coal and cracks it generally radially outwardly to the inner surface of the cylinder and immediately commences exerting rearward pressure on it. As the head turns more and more rearward pressure is exerted on the lumps of coal by the screw of increasing size, the rate of speed of the head into the face preferably being relatively slow as compared with the rate of rearward delivery of the coal by the screw. Hence the coal is quickly removed from the zone of the front end of the screw and by the portion 3 of the screw is delivered rearwardly out of the cylinder 8.

If the cylinder should be advanced into the face a distance greater than its own length the portion I of the screw which extends rearwardly from the cylinder will cooperate with the inner surface of the bore formed in the face to deliver the coal outwardly therefrom. The thu's delivered coal is removed by any suitable means.

Instead of having the forward extremity of the screw conveyor tapered or reduced to smaller diameter I may make the screw conveyor of uniform diameter from end to end but with the front end thereof behind the breaking tool. In such case it is desirable to provide on the shaft between the inner cutting means and the screw conveyor means breaking material and propelling it rearwardly. Such a structure is shown in Figures 3, 4 and 6 which depict a mining machine head which is presently preferred because of its strength and ruggedness and because of its relatively low cost of manufacture. Parts in Figures 3, 4 and 6 which are the same as parts in Figures 1, 2 and 5 are designated by the same reference numerals as are applied to those parts in Figures 1, 2 and 5 but with a prime affixed.

The form of Figures 3, 4 and 6 differs from the form of Figures 1, 2 and 5 primarily in that in the form of Figures 3, 4 and 6 the screw 3' does not have a tapered nose portion corresponding to the tapered nose portion 5 of the screw 3. The screw 3' is of the same diameter from end to end, terminating at its front end in an edge II. The edge I3 is disposed at approximately the rear end of the tapered portion 6' of the shaft 2'. A cutting tool I is carried by the shaft 2' at its forward end as in the form of Figures 1, 2 and 5 but the front ends of the cutters of the tool I are disposed closer to the front end of the mining machine head in the form of Figures 3, 4 and 6 than in the form of Figures 1, 2 and 5. I find it desirable to have the front end of the tool I relatively close to the front end of the mining machine head although the position of the tool is subject to some variation. In Figure 6 the front end of the cutting tool 1' is somewhat in advance of the front ends of the cutters 9', III and II.

In Figures 3, 4 and 6 I show curved or spiral ribs H welded to the tapered portion 8' of the shaft 2', some of the ribs ll commencing close to the cutting tool I and others commencing farther back on the tapered portion 6'. The ribs ll terminate at approximately the transverse plane of the edge H at the front end of the screw 3'. The curvature of the ribs is consonant with the direction of advance of the screw so that the ribs in effect form a forward extension of the screw. The ribs I! serve to propel rearwardly material broken up by the breaking tool comprising the tapered shaft portion 8 having the ribs thereon and cooperate with the screw 3 to deliver the broken-up material away from the face. Thus the tapered nose portion Ii of the shaft 2' with the ribs ll thereon forms in effect a reduced front end on the screw 3. The ribs preferably diverge in the direction from the forward end toward the rearward end of the breaker so that the passage space therebetween increases in cross-sectional area in the direction from the forward end toward the rearward end of the breaker. It is much cheaper to weld the ribs ll onto the shaft than it is to form the portion of reduced diameter at the front end of the screw I in the form of Figures 1, 2 and 5; also the danger of deformation or breakage of the reduced front end of the screw is eliminated. The breaker of Figures 3, 4 and 6 has otherwise the same structural and operating characteristics as the breaker of Figures 1, 2 and 5 and functions in the same manner. The above description of the breaker of Figures 1, z and 5 and its operation applies generally to the breaker of Figures 3, 4 and 6 and its operation.

In Figures 3, 4 and 6 there is shown in addition to the outside spiral projection I! a series of inside spiral projections it which lead in the same direction as the outside spiral projection l2 and aid in projecting or advancing rearwardly material severed from the face by the cutters 9' and HI and broken up by the tool I. The inside spiral projections i5 extend from approximately the front edge of the cylinder 8' rearwardly for a short distance although they may be extended rearwardly all the way to the front end of the screw 3' if desired.

The cutters 9', III and H of Figures 3, 4 and 6 correspond respectively with the cutters 9, III and of Figures 1, 2 and 5. In Figures 3, 4 and 6 the cutters II are arranged in the same transverse plane as the cutters 9' and it instead of being disposed in a separate transverse plane to the rear of the plane of the other cutters as in the form of Figures 1, 2 and 5. The inside outters li' may have their radially inside surfaces lying approximately in a cylinder defined by the radially inside surfaces of the inside spiral projections it.

In both the form of head shown in Figures 1, 2 and 5 and the form of head shown in Figures 3, 4 and 6 there is embodied a rotatable and advanceable cutter element having a material passage therethrough extending generally parallel to the axis of rotation and having periphery cutting means mounted thereon at the forward end thereof disposed to cut a generally cylindrical kerf in a body of material upon rotation and advancement of the cutter element, the cutter element taking the form of a cylinder open at both ends and carrying adjacent its forward end periphery cutting means for cutting into a body of material upon rotation and advancement of the cylinder; there is a breaker coaxial with the cutter element within and connected with the cylinder, the breaker at a zone not substantially in advance of the periphery cutting means being of a width approximating that of inner cutting means mounted on its forward end and specifically having its forward end rearwardly of the periphery cutting means; the breaker is small enough at its forward end to enter the opening formed by the inner cutting means but is wider than that opening at its rearward end; the breaker has outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially adjacent convolutions of the conveyor are spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib means; the conveyor is pitched and the passage space is proportioned to the size of the inner cutting means so that the passage space accommodates and the conveyor conveys rearwardly substantially all of the cuttings formed by the inner cutting means which enter the passage space and the conveyor engages and propels rearwardly lumps of the material; the breaker comprises a tapered core having conveying rib means on the exterior thereof; the passage space between adjacent convolutions of the conveyor increases in crosssectional area in the direction from the forward end toward the rearward end of the breaker; the conveying rib means diverge in the direction from the forward end toward the rearward end of the breaker; there is provided a rotatable spiral conveyor extending rearwardly from the cylinder, the annular space within the cylinder about and rearwardly of the breaker being completely open to deliver material unimpeded from within the cylinder to the last mentioned spiral conveyor; and the last mentioned spiral conveyor is connected with the cylinder and is rotatable and advanceable therewith and extends rearwardly therefrom, the cylinder being mounted solely on the periphery of the last mentioned spiral conveyor.

While I have shown and described certain present preferred embodiments of the invention it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied within the scope of the following claims.

I claim:

1. A mining machine head comprising a rotatable and advanceable cylinder open at both ends, periphery cutting means carried by the cylinder adjacent the forward end thereof for cutting into a body of material upon rotation and advancement of the cylinder, a breaker coaxial with the cylinder within and connected with the cylinder having its forward end rearwardly of the periphery cutting means, and inner cutting means mounted on the forward end of the breaker, the breaker being small enough at its forward end to enter the opening formed by the inner cutting means but being wider than that opening at its rearward end, the breaker having outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially, adjacent convolutlons of the conveyor being spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib means, the conveyor being pitched and the passage space being proportioned to the size of the inner cutting means so that the e space accommodates and the conveyor conveys rearwardly substantially all of the cuttings formed by the inner cutting means which enter the passage space and the conveyor engages and propels rearwardly lumps of the material.

2. A mining machine head comprising a rotatable and advanceable cylinder open at both ends, periphery cutting means carried by the cylinder adjacent the forward end thereof for cutting into a body of material upon rotation and advancement of the cylinder, a breaker coaxial with the cylinder within and connected with the cylinder having its forward end rearwardly of the periphery cutting means, and inner cutting means mounted on the forward end of the breaker, the breaker being small enough at its forward end to enter the opening formed by the inner cutting means but being wider than that awash opening at its rearward end and comprising a tapered core having on the exterior thereof outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially, adjacent convolutlons of the conveyor being spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib means, the conveyor being pitched and the passage space being proportioned to the size of the inner cutting means so that the passage space accommodates and the conveyor conveys rearwardly substantially all of the cuttings formed by the inner cutting means which enter the passage space and the conveyor engages and propels rearwardly lumps of the material.

3. A mining machine head comprising a rotatable and advanceable cylinder open at both ends, periphery cutting means carried by the cylinder adjacent the forward end thereof for cutting into a body of material upon rotation and advancement of the cylinder, a breaker coaxial with the cylinder within and connected with the cylinder having its forward end rearwardly of the periphery cutting means, and inner cutting means mounted on the forward end of the breaker, the breaker being small enough at its forward end to enter the opening formed by the inner cutting means but being wider than that opening at its rearward end, the breaker having outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially, adjacent convolutions of the conveyor being spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib means, the passage space increasing in crosssectional area in the direction from the forward end toward the rearward end of the breaker.

4. A mining machine head comprising a rotatable and advanceable cylinder open at both ends, periphery cutting means carried by the cylinder adjacent the forward end thereof for cutting into a body of material upon rotation and advancement of the cylinder, a breaker coaxial with the cylinder within and connected with the cylinder, and inner cutting means mounted on the forward end of the breaker, the inner cutting means having its forward end rearwardly of the periphery cutting means, the breaker being small enough at its forward end to enter the opening formed by the inner cutting means but being wider than that opening at its rearward end, the breaker having outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially, adjacent convolutions of the conveyor being spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib means, the conveyor being pitched and the passage space being proportioned to the size of the inner cutting means so that the passage space accommodates and the conveyor conveys rearwardly substantially all of the cuttings formed by the inner cutting means which enter the passage space and the conveyor engages and propels rearwardly lumps of the mate- 5. A mining machine head comprising a rotatable and advanceable cylinder open at both ends, periphery cutting means carried by the cylinder adjacent the forward end thereof for cutting into a body of material upon rotation and advancement of the cylinder, a breaker coaxial with the cylinder within and connected with the cylinder having its forward end rearwardly of the periphery cutting means, inner cutting mea mounted on the forward end of the breaker, e breaker being small enough at its forward end to enter the opening formed by the inner cutting means but being wider than that opening at its rearward end, the breaker having outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially, adjacent convolutions of the conveyor being spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib means, the conveyor being pitched to engage and propel rearwardly lumps of the material, and a rotatable spiral conveyor extending rearwardly from the cylinder, the annular space within the cylinder about and rearwardly of the breaker being completely open to deliver material unimpeded from within the cylinder to the last mentioned spiral conveyor.

6. A mining machine head comprising a rotatable and advanceable cylinder open at both ends, periphery cutting means carried by the cylinder adjacent the forward end thereof for cutting into a body of material upon rotation and advancement of the cylinder, a breaker coaxial with the cylinder within and connected with the cylinder having its forward end rearwardly of the periphery cutting means, inner cutting means mounted on the forward end of the breaker, the breaker being small enough at its forward end to enter the opening formed by the inner cutting means but being wider than that opening at its rearward end, the breaker having outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially, adjacent convolutions of the conveyor being spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib means, and a spiral conveyor connected with the cylinder, rotatable and advanceable therewith and extending rearwardly therefrom, the cylinder being mounted solely on the periphery of the last mentioned spiral conveyor.

7. A mining machine head comprising a rotatable and advanceable cylinder open at both ends, periphery cutting means carried by the cylinder adjacent the forward end thereof for cutting into a body of material upon rotation and advancement of the cylinder, a breaker coaxial with the cylinder within and connected with the cylinder having its forward end rearwardly of the periphery cutting means, and inner cutting means mounted on the forward end of the breaker, the breaker being small enough at its forward end to enter the opening formed by the inner cutting means but being wider than that opening at its rearward end, the breaker having outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch'extending rearwardly and circumferentially, adjacent convolutions of the conveyor being spaced apart to provide passage space, the rib means diverging in the direction from the forward end toward the rearward end of the breaker.

8. A mining machine head comprising a rotat-- able and advanceable cutter element having a material passage therethrough extending generally parallel to the axis of rotation and having periphery cutting means mounted thereon at the forward end thereof disposed to cut a generally cylindrical kerf in a body of material upon rotation and advancement of the cutter element,

asaaan a breaker coaxial with the cutpr element and connected therewith, and inner cutting means mounted onihe forward end of the breaker, the breaker bll'imall enough at its forward end to enter the opening formed by the inner cutting means but being wider than that opening at its "rearward end, the breaker at a zone not sube' tantially in advance of the periphery cutting means being of a width approximating that of the inner cutting means, the breaker having outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially, adjacent convolutions of the conveyor being spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib means, the conveyor being pitched and the passage space being proportioned to the size of the inner cutting means so that the passage space accommodates and the conveyor conveys rearwardly substantially all of the cuttings formed by the inner cutting means which enter the passage space and the conveyor engages and propels rearwardly lumps of the material.

9. A mining machine head comprising a rotatable and advanceable cutter element having a material passage therethrough extending generally parallel to the axis of rotation and having periphery cutting means mounted thereon at the forward end thereof disposed to cut a generally cylindrical kerf in a body of material upon rotation and advancement of the cutter element, a breaker coaxial with the cutter element and connected therewith and having its forward end rearwardly of the periphery cutting means, and inner cutting means mounted on the forward end of the breaker, the breaker being small enough at its forward end to enter the opening formed by the inner cuttin means but being wider than that opening at its rearward end, the breaker having outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially, adjacent convolutions of the conveyor being spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib means, the conveyor being pitched and the passage space being proportioned to the size of the inner cuttin means so that the passage space accommodates and the conveyor conveys rearwardly substantially all of the cuttings formed by the inner cutting means which enter the passage space and the conveyor engages and propels rearwardly lumps of the material.

10. A mining machine head comprising a rotatable and advanceable cylinder open at both ends, periphery cutting means carried by the cylinder adjacent the forward end thereof for cutting into a body of material upon rotation and advancement of the cylinder, 9, breaker coaxial with the cylinder within and connected with the cylinder, and inner cutting means mounted on the forward end of the breaker, the breaker being small enough at its forward end to enter the opening formed by the inner cutting means but being wider than that opening at its rearward end, the breaker at a zone not substantially in advance of the periphery cutting means being of a width approximating that of the inner cutting means, the breaker having outwardly projecting rib means forming a generally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentially, adjacent convolutions of the conveyor being spaced apart to provide passage space therebetween of materially greater crosssectional area than the rib means, the conveyor being pitched and the passage space being proportioned to the size of the inner cutting mean so that the passage space accommodates and the conveyor conveys rearwardly substantially all of the cuttings formed by the inner cutting means which enter the passage space and the conveyor engages and propels rearwardly lumps of the material.

ii. A mining machine head comprising a rotatable and advanceable cutter element having a material passage therethrough extending generally parallel to the axis of rotation and having periphery cutting means mounted thereon at the forward end thereof disposed to cut a generally cylindrical kerf in a body of material upon rotation and advancement of the cutter element, a breaker coaxial with the cutter element and connected therewith, and inner cutting means mounted on the forward end of the breaker, the breaker being small enough at its forward end to enter the opening formed by the inner cutting means but being wider than that opening at its rearward end, the breaker at a. zone not substantially in advance of the periphery cutting means being of a width approximating that of the inner cutting means, the breaker having outwardly projecting rib means forming a enerally spiral conveyor of relatively coarse pitch extending rearwardly and circumferentiaily, adjacent convolutions of the conveyor being spaced apart to provide passage space therebetween of materially greater cross-sectional area than the rib means, the conveyor being pitched and the passage space being proportioned to the size of the inner cutting means so that the passage space accommodates and the conveyor conveys rearwardly substantially all of the cuttings formed by the inner cutting means which enter the passage space and the conveyor engages and propels rearwardly lumps of the material, the passage space increasing in cross-sectional area in the direction from the forward end toward the rearward and of the breaker.

12. A mining machine head comprising a retatable and advanceable shaft, a spiral conveyor disposed about the shaft and mounted thereon for rotating and advancing movement with the shaft and adapted to convey rearwardly about the shaft material entering the forward end of the conveyor, a cylinder open at both ends substantialy coaxial with the shaft and mounted upon the spiral conveyor for rotating and advancing movement with the shaft and spiral conveyor, periphery cutting means carried by the cylinder adjacent the forward end thereof for cutting into a body of material upon rotation and advancement of the cylinder, a breaker on the forward end of the shaft substantially coaxial with the cylinder, disposed within the cylinder and having its forward end rear-wardly of the periphery cutting means, and inner cutting means mounted on the forward end of the breaker, the breaker being small enough at its forward end to enter the opening formed by the inner cutting means but being wider than that opening at its rearward end, the breaker having outwardly projecting rib means formin a generally spiral conveyor portion of relatively coarse pitch extending rearwardly and circumferentially substantially to the first mentioned spiral conveyor, adjacent convolutions of said spiral conveyor portion being spaced apart to provide passage space therebetween of materially greater crosssectional area than the rib means. the spiral conveyor portion being pitched and the passage space being proportioned to the size of the inner cutting means so that the passage space accommodates and the spiral conveyor portion conveys rearwardly to the first mentioned spiral conveyor substantially all of the cuttings formed by the inner cutting means which enter the passage space and the spiral conveyor portion engages and propels rearwardly lumps of the materiaL CHARLES E. COMPTON.

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

Number Number 14 UNITED STATES PATENTS Name Date Woiford Jan. 13, 1891 Tonge. Jr. Sept. 19, 1905 Walker July 2, 1918 Joy July 30, 1918 Joy Feb. 13, 1923 Hansen b. Aug. 19, 1924 FOREIGN PATENTS Country Date Germany May 12, 1900

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