US2749675A

US2749675A - Abrasive grinding machines

Info

Publication number: US2749675A
Application number: US432639A
Authority: US
Inventors: Wilbert W Frank; Cleaver C Speer
Original assignee: Curtiss Wright Corp
Current assignee: Curtiss Wright Corp
Priority date: 1954-05-27
Filing date: 1954-05-27
Publication date: 1956-06-12
Anticipated expiration: 1973-06-12

Description

June 12, 1956 w. w. FRANK ETAL ABRASIVE GRINDING MACHINES 5 Sheets-Sheet 1 Filed May 27, 1954 Summers CLEAVER C. SPEER WILBERT W. FRANK Quorum} June 12, 1956 w. w. FRANK ETAL 2,749,675

ABRASIVE GRINDING MACHINES Filed May 27, 1954 s Sheets-Sheet 2 III-II 3nventor$ CLEAVE R C. SPEER WILBERT W. FRANK (Ittorneg FIG.2

June 12, 1956 w. w. FRANK ET AL ABRASIVE GRINDING MACHINES 5 Sheets-Sheet 3 Filed May 27, 1954 Snoentors CLEAVER C.SPEER WILBERT W. FRANK (Ittorneg June 12, 1956 w. w. FRANK ET AL.

ABRASIVE! GRINDING MACHINES 5 Sheets-Sheet 4 Filed May 27, 1954 FIG.6

IL WE w w M m w T m B L u w June 12, 1956 w. w. FRANK ETAL ABRASIVE GRINDING MACHINES 5 Sheets-Sheet 5 Filed May 27, 1954 Znwentors CLEAVER C.SPEER WILBERT W. FRANK United States Patent ABRASIVE GRINDING MACHINES Wilbert W. Frank, Long Valley, and Cleaver C. Speer, Passaic, N. 1., assiguors to Curtiss-Wright Corporation, a corporation of Delaware Application May 27, 1954, Serial No. 432,639

18 Claims. (Cl. 51-143) This invention relates to abrasive belt grinding machines and is concerned particularly with an abrasive belt grinding machine adapted to accurately grind the exterior surfaces of metal tubes.

The machine includes automatic controls and adjustments which render it flexible and usable for various sizes and kinds of work. These auxiliary features of the machine will be better appreciated by reading the annexed detailed description.

The machine of this invention was developed particularly for finishing hollow steel propeller blades fabricated from extruded blanks. It has been found that the extruded blanks are not sufiiciently precise, as extruded, to come Within the desired dimensional limits which are required in a finished propeller blade. Accordingly, it has been necessary to devise machining methods to provide accurate dimensional control of the propeller blade blanks. It is an object of the present invention to provide a machine which is capable of machining tubular propeller blade blanks in a very accurate manner.

It is a further object of the present invention to provide an abrasive belt grinding machine capable of controlling the wall thickness of tubes within very close limits. A further object of the invention is to provide control of abrasive belt grinding to enable the grinding of tube walls to various pre-determined thicknesses. Another object is to provide an abrasive belt grinding machine wherein the thickness of a tubular work piece wall may be graded according to a pre-determined pattern.

Further objects of the invention will become apparent from reading the annexed detailed description which is illustrated by the attached drawings showing an example of the machine of the invention. In the drawings, similar reference characters indicate similar parts and Fig. 1 is a side elevation of the machine of the invention showing most of the components thereof,

Fig. 2 is an enlarged side elevation showing part of the belt driving head,

Fig. 3 is a view on the line 33 of Fig. 2,

Fig. 4 is a side elevation, partly in section, showing the part of the machine where an abrasive belt engages a work piece,

Fig. 5 is a section on the line 5-5 of Fig. 4,

Fig. 6 is a perspective elevation of the part of the machine where the abrasive belt is engageable with a tubular work piece,

Fig. 7 is a side elevation of the part of the machine which holds the work piece and constitutes a translatable carriage, and

Fig. 8 is a view on the line 88 of Fig. 1.

Reference may be made to Fig. 1 which shows the machine in its entirety. The machine comprises a long, slender bench 10 on the leftward end of which (as shown) is secured a support 12 in which is firmly clamped a mandrel member, or anvil, 14. This member 14 comprises a strong, stiff bar or tube and extends rightwardly from the support 12 a considerable distance.

Over this mandrel "ice 14, a tubular work piece 16 is adapted to be translated back and forth. The right-hand end of the mandrel 14 carries a roller 18, the upper rim of'which extends above the upper surface of the mandrel to engage the inner wall surface of the tubular piece 16 and to support same.

Toward the left-hand end of the bench 10 is an elevated frame 20 carrying a motor 22. On the frame 20 is a bracket 24, hinged to the frame at 26 and vertically adjustable relative to the frame 20 as by a screw adjustment 28. The bracket 24 carries a bearing 29 for a driving pulley 30 over which runs an abrasive belt 32. The pulley 30 is driven from the motor 22 by a belt 33. Figs. 2 and 3 show this arrangement in greater detail and will be described in more detail shortly. Adjacent to the pulley 30 and secured to the bearing 29 are support arms 34 extending in a rightward direction, these support arms 34 being adjustable relative to the bearing 29 both longitudinally and laterally as will be covered in subsequent description. The right-hand ends of the arms 34 carrying fittings 132 journalling an idler pulley 36 over which the abrasive belt 32 runs. The idler pulley 36 provides the means by which the effective surface of the abrasive belt is brought into engagement with the outer surface of the tubular work piece 16. The idler pulley 36 is guided and controlled in its vertical position by a feed head mechanism 38 described later and shown in more detail in Figs. 4, 5 and 6. The head 38 is movable vertically and is carried by a frame 40 which rises from about the mid-point of the main bench 10.

The upper surface of the bench 10 at its right-hand end comprises a pair of parallel spaced tracks 44 and 46. Resting upon these tracks, through wheels 48, is a translatable carriage 50. The carriage 50 and its arrangements are shown in greater detail in Fig. 7. Beneath the tracks 44 and 46 is a longitudinally extending lead screw 52 which may be rotatably driven in either direction by a reversible motor at the end of the machine, this motor not being shown since it is conventional in its construction. By ro tation of the lead screw in one direction or the other, the carriage 50 is translated either to the left or to the right, the carriage having a nut 54 secured thereto which engages the screw 52. In lieu of a lead screw, the carriage may be translated by a hydraulic or pneumatic ram or other linear motor means.

To an elevated bracket 55 on the carriage 50 is secured a linear cam bar 56, as at a pivot 58. The cam bar extends leftwardly and engages a portion of the feed head 38 to control the vertical position thereof as the tubular work piece 16 is translated leftwardly or rightwardly by the carriage 50. The cam bar is formed to provide varying thicknesses in the working range which will be translated to rise and fall of the head 38 to control the thickness of grinding of the wall of the tubular work piece 16. This control will be shortly understood when a detailed description of the head 38 in connection with Figs. 4, 5 and 6 is given. Also, risers 57, toward the ends of the cam bar 56, serve to lift the pulley 36 and abrasive belt 32 from the work piece 16 at the ends of the stroke of the carriage 50.

The carriage 50, as shown in Figs. 1 and 7, is provided with a table 62 which is adjustable in height relative to the carriage proper, by means of a screw shaft 64, a worm wheel 66, and a manually controlled worm 68 driven by a hand wheel 70. This enables accommodation in the machine of tubular work pieces of various diameters. On the table 62 are trunnions 72 in which a barrel 74 is journalled for tilt in a vertical plane. This barrel 74 carries through shaft 76 to the left-ward end of which a chuck 78 is secured. In the chuck, the tubular work piece 16 may be clamped. The shaft 76 extends rightwardly beyond the barrel 74 and is provided at its end with counterweights 80 which are adjustable to balance the weight of the tubular work piece 16 about the trunnions. By this counterbalancing as the tubular work piece 16 travels over the mandrel 14, there is no great bearing load of thework piece on the support roller 18. In practice, the balance of the tubular work piece is of an order so that there may be a very few pounds of pressure of the work piece on the roller 18. The counterweights $9 balance the rest of the weight of the tubular work piece.

The shaft 76 carries a yoke 82 which is oscillatable about the axis of the shaft 76, the yoke having opposite facing

pawls

84 and 86 which are engageable with

ratchet wheels

88 and 30 keyed to the shaft 7 6. By oscillating the yoke 82 a few degrees according to the adjustment of the

pawls

84, 86, the shaft 76 with its chuck 78 and the work piece 16 may be turned a few degrees about the axis in either direction to bring fresh portions of the tubular work piece under the abrasive belt 32. in order to effect this rotary feed of the work piece, the yoke is provided with a depending bar 92 which engages a rail 94 secured on the bench it) below and between the tracks 4 46. The rail 94 is equipped with sloped cams 96 and 93. As the carriage travels to and fro along the tracks 44, the bar 92 rides the rail $4 until the end of the stroke is approached, at which time the bar 92 engages the sloped face of one of the cams 96 or 98, thereby oscillating and indexing the shaft 76. The

pawls

84 and 86 index the ratchet wheels and are adjustable to control the direction of feed of the rotating shaft 76, by a rocker 1th} on the shaft of the pawls. The rocker is held in one position or the other by an over-center spring 102. The bar 92 is normally spring urged to engage the rail 94 by means of a spring 104 shown in Figs. 7 and 8.

The right-hand end of the frame adjacent tracks 4-4, 46, carries spaced limit switches 106 and 19S, engageable at times by a striker 110 on the carriage 56. These limit switches control the circuit of the motor which drives the lead screw 52. For instance, when the striker 110 strikes the limit switch 108, the driving motor is stopped and reversed in direction to cause translation of the carriage Sil toward the left. When the striker 110 engages the limit switch 126, the driving motor for the lead screw is stopped and reversed in direction to cause translation of the carriage 50 toward the right. Thus, continuous back and forth motion of the carriage is provided for, along with indexing of the tubular work piece, rotationally, at the end of each stroke.

Attention is now invited to Figs. 1, 2 and 3 and following is a more detailed description of the mechanism involved in the driving head for the abrasive belt. As was previously mentioned, the belt driving motor 22 drives the abrasive belt 3-2 through a belt 33 and a pulley 3b. The pulley is journaled as shown in Fig. 3 in a member 29 which latter is pivotally secured, for swinging in a vertical plane, to the adjustable bracket 24. This bracket is adjustable vertically through the means 28 comprising a screw 112 equipped with a hand wheel 113. The purpose of this adjustment is to adjust tension of the belt 33 between the motor 22 and the pulley 30.

As shown in Fig. 3, the member 29 is provided with a pivot 1115 upon which is journaled a fitting 116 from which the arms 34 project to the right as shown. Fitting 116 and the arms 34 are swingable laterally about the pivot 115 in order to adjust the alignment of the abrasive belt 3'2 to enable it to run true, without run-off, over the driving pulley 3i) and the idler pulley 36. To enable this lateral adjustment, a screw shaft 118 engages nuts 119 and 120 respectively secured to the member 29 and to the member 116. Adjustment of the screw 11?- is enabled by a hand wheel 122 on the screw. By rotating the wheel 1.22 in one direction or the other, the arm 34 may be swung laterally with respect to the member 29.

As shown in Figs. 2 and 3, the arms 34 are adjustabtly secured in the fitting 116 so they may move right-wardly or left-wardly with respect thereto. The coupling of these two members includes a pneumatic piston-cylinder motor on or oil the abrasive belt grinding motor 22.

generally designated at 124 which may be fed at the left end with compressed air through a conduit 126, and the right end with compressed air through a conduit 128. When it is desired to replace a belt 32, compressed air is bled from the conduit 126 and fed to the conduit 128. This causes the arms 34 to move left-wardly with respect to the fitting 116, loosening the belt and enabling inrtallation of a replacement belt over the

pulleys

30 and 36. Upon installation of the new belt, compressed air is bled from conduit 126 and is fed to the conduit 126. This causes the arms 34 to move to the right, tightening the belt 32. The air pressure fed to the conduit 126 is held at a level to give proper tension in the abrasive belt 32 causing it to be tight enough to prevent whipping and to feed properly over the idler pulley 36, yet not tight enough to break the belt. By this arrangement, expeditious changing oi belts upon wearing or breakage thereof may be accomplished, and continuous proper tightness of the belt is maintained during the grinding operation.

Reference may now be made to Figs. 4, 5 and 6 which show the adjusting arrangement for the idler pulley 36 over which the abrasive belt 32 runs. The idler pulley 1s iournaled in a fitting 132 secured to the ends of the arms 34. It is also pivotally secured to a link 134, the upper end of which is secured to the feed head 38. This feed head 38, as noted in Fig. 5 is vertically slideable in guides 136 secured to the support 40. Suitable gibs 138 and gib adjusting screws 14% are provided to enable an effective fit for sliding between the head 38 and the guides 136. Within the head 33 are slides 142 engaging a yoke 144 vertically adjustable relative to the head. This adjustment is accomplished by a micrometer screw 146 engaging the yoke 144, threadedly engaging the top of the head 38, and passing upwardly to an adjusting wheel 148 above the guides 136. This screw may be calibrated in any suitable units such as thousandths of an inch. The yoke 144 has journaled therein a roller 150 which bears against and rolls upon the surface of the cam bar 56. The cam bar 56 in turn rests upon and moves along a roller 152 which is journaled in the lower part of the head guiding assembly 136 in turn supported on the structure 40.

The foregoing structure enables rise and fall of the idler pulley 36 in conformance with the thickness of the cam bar 56. The cam bar separates the

rollers

152 and 156, the roller 152 having a fixed axis, and thus the roller 15% is caused to rise and fall, carrying the idler pulley 36 with it as the thickness of the cam bar varies while it is being moved longitudinally of itself through or between the rollers. The screw 146 enables adjustment of the idler roller 36 for feeding purposes and to establish the s ecific thickness of the work piece 16 which may be desired. The weight of the head 38 is normally sufficient to provide feed pressure and this may be augmented if needed by springs or motor devices.

In Fig. 4 it will be noted that the work piece 16 rests upon the roller 18, and belt 32 running over the idler pulley 36 abrades the outer surface of the work piece and brings it down to the thickness as established by the setting of the screw 146 and the thickness of the cam bar 56. The cam bar varies along its length, in thickness, which enables the grinding of the Work piece 16 to tapered thickness from one end to the other, or to any desired thickness configuration. For protecting the cam bar 56, it moves in and out of a tube 156. This prevents grinding dust, which is thrown leftwardly of the idler pulley 36 during operation, from gathering on the surfaces of the cam bar and modifying the effective thickness of the bar.

In Fig. 1 several control switches are shown. The switch 153 is arranged for manual control of the carriage 50 during setting-up operation. The switch is arranged to initiate automatic control of the carriage and its driving motor. The switch 162 is arranged to turn In adgates-75 dition to these controls, a pneumatic control for the belt arms 34 is arranged at a convenient location.

Any suitable sort of abrasive belt 32 may be used in this machine. For instance, a rough, large grit abrasive may be used for rough cutting the work piece and to re move considerable material therefrom. When finishing or polishing operations are desired, finer grit abrasive belts may be installed quickly upon the machine. It has been found that the abrasive belt should operate at high linear speeds in order efiectively to remove metal from the work piece and also to increase the life and effectiveness of the abrasive belt. It will further be seen that there are numerous features of adjustability for the machine to enable its adaptation to work pieces of various diameters and lengths.

A particular feature of the machine of this invention is that very accurate surface grinding may be accomplished thereon even though there is considerable overhang of the various supporting components and of the work piece itself. Control of the abrasive head at the pulley 36 is accomplished directly thereat so that its positioning in space is accurately established. The supporting mandrel 14 for the work piece has considerable overhang from its anchorage and accordingly, may have some droop. So long as the load on the roller 18 is maintained substantially constant, there will be little variation in the droop at the end of the mandrel 14. This low variation in load on the mandrel I4 is taken care of by counterbalancing of the work piece 16 through the counterbalances 80. Thus, the weight of the tube 16 bearing upon the roller 18 may be adjusted from a few ounces to a few pounds, at least to a low enough valve so that there will be little efiect in variation of droop of the mandrel 14. This enables grinding of the work piece wall to desired thicknesses and within very small tolerances such as, for instance, .004". Additionally, compensation for varying mandrel droop may be incorporated in the profile of the cam bar 56.

When the workpiece 16 is barely over the mandrel 14 and is counterbalanced to bear at, say two pounds on the roller 18, this pressure will increase as the trunnions 72 approach the roller 18. This pressure increase, increases the droop deflection of the mandrel 14. This deflection can be evaluated easily, and the thickness of the cam bar 56 can be gradually reduced from the left end toward the right end to compensate it.

A micrometer or dial indicator can be mounted on the guide 136 to enable int-place thickness checking and inspection of the rough and finished tube wall thickness.

In the drawings, limit switches 106 and 108 and indexing cam 94 are disposed at the right end of the bench and operate in cooperation with the carriage 50. Alternatively, limit and indexing switches may be mounted on the standard 40 and can be operated by cam lobes made integral with or attached to the cam bar 56. This arrangement is deemed to come within the scope of the invention, and has certain advantages. For instance, a cam bar 56 for a particular model of tubular workpiece will carry as part thereof, stroke-limiting cams, a thickness control cam, and an indexing control cam. All needed adjustments would thus be carried on a single replaceable cam bar, avoiding the need for resetting stroke and indexing limits when a different model tubular work piece is to be ground.

While an embodiment of the invention has been shown and described, it is to be understood that the invention may be applied in other and various forms. Changes may be made in the arrangements shown without departing from the spirit of the invention. Reference should be had to the appended claims for definitions of the limits of the invention.

What is claimed is:

1. An abrasive belt grinding machine for profiling tubular members comprising a fixed work support member having a roller at one end over which a tube work piece is adapted to be passed, an abrasive belt idler pulley disposed adjacent said roller, means to drive an abrasive belt over said pulley at high speed, an adjustable support for said pulley moveable to change the space between said pulley and said roller; a translatable carriage including a trunnion, means supported by said trunnion for tiltably holding the tubular work piece for travel with said carriage for passing a wall of said work piece between said roller and pulley, and a cam bar secured to said carriage and translatable therewith, said cam bar being profiled to control desired work piece wall thickness variations and engaging said adjustable pulley support to control the movement thereof.

2. An abrasive belt grinding machine for profiling tubular members comprising a fixed work support member having a roller at one end over which a tube work piece is adapted to be passed, an abrasive belt idler pulley disposed adjacent said roller, means to drive an abrasive belt over said pulley at high speed, an adjustable support for said pulley movable to change the space between said pulley and said roller; a translatable carriage including a trunnion, means supported by said trunnion for tiltably holding the tubular work piece for travel with said carriage for passing a wall of said work piece between said roller and pulley, and a cam bar secured to said carriage and translatable therewith, said cam bar being profiled to control desired work piece wall thickness variations and engaging said adjustable pulley support to control the movement thereof, said adjustable pulley support including an adjuster independent of said cam bar.

3. In an abrasive belt grinding machine comprising a work piece holder and a swingable belt-carrying arm engageable with a work piece on the holder, the arm and holder being relatively movable for grinding an area on the work piece; an adjustable member secured to the arm adjacent the work-engaging end thereof, a cam movable in coordination with relative movement of said holder and arm, and a cam-follower engaging said cam secured to said adjustable member for controlling the feed position thereof relative to said work piece holder, the relative movement of said arm and bolder being longitudinally reciprocative, and means responsive to successive reciprocations to elfect lateral feed of said arm and holder.

4. In an abrasive belt grinding machine comprising a reciprocable work piece carriage adapted to hold a workpiece fiexibly thereon, and a belt-carrying arm, said arm including pulleys and a belt running thereover the belt extending in the general direction of reciprocation of said carriage, one of said pulleys being adjustable in a path for engaging the belt running thereover with a work piece, and a support for the work piece lying on the opposite side of the work piece from said one pulley.

5. In an abrasive belt grinding machine comprising a reciprocable work piece carriage adapted to hold a workpiece carriage adapted to hold a workpiece flexibly thereon, and a belt-carrying arm, said arm including pulleys and a belt running thereover the belt extending in the general direction of reciprocation of said carriage, one of said pulleys being adjustable in a path for engaging the belt running thereover with a work piece, a support for the work piece lying on the opposite side of the work piece from said one pulley, and means responsive to carriage reciprocation to adjust the said one pulley relative to said work piece support.

6. In an abrasive belt grinding machine comprising a reciprocable work piece carriage and a belt-carrying arm including an end disposed close to a work piece on the carriage, said arm including pulleys and a belt running thereover the belt extending in the general direction of reciprocation of said carriage, one of said pulleys being adjustable in a path for engaging the belt running thereover with a work piece, a support for the work piece lying on the opposite side of the work piece from said one pulley, a cam bar secured to said carriage and reciprocable therewith, and means engaging said cam bar and operated thereby to adjust the spacing between said one pulley and said work piece support.

7. In an abrasive belt grinding machine comprising a reciprocable work piece carriage and a belt-carrying arm including an end disposed close to a work piece on the carriage, said arm including pulleys and a belt running thereover the belt extending in the general direction of reciprocation of said carriage, one of said pulleys being adjustable in a path for engaging the belt running thereover with a work piece, a support for the work piece lying on the opposite side of the work piece from said one pulley, a cam bar secured to said carriage and reciprocable therewith, means engaging said cam bar and operated thereby to adjust the spacing between said one pulley and said work piece support, and means actuated by carriage movement toward the ends of its stroke to reverse the movement thereof.

8. In an abrasive belt grinding machine comprising a reciprocable work piece carriage and a belt-carrying arm including an end disposed close to a Work piece on the carriage, said arm including pulleys and a belt running thereover the belt extending in the general direction of reciprocation of said carriage, one of said pulleys being adjustable in a path for engaging the belt running thereover with a work piece, a support for the work piece l 'ing on the opposite side of the work piece from said one pulley, a cam bar secured to said carriage and reciprocable therewith, means engaging said cam bar and operated thereby to adjust the spacing between said one pulley and said work piece support, and means actuated by carriage movement toward the ends of its stroke to index the work piece for feed transverse to the direction of carriage reciprocation,

9. In an abrasive belt grinding machine comprising a reciprocable work piece carriage and a belt-carrying arm including an end disposed close to a work piece on the carriage, said arm including pulleys and a belt running thereover the belt extending in the general direction of reciprocation of said carriage, one of said pulleys being adjustable in a path for engaging the belt running thereover with a work piece, a support for the work piece lying on the opposite side of the work piece from said one pulley, a cam bar secured to said carriage and reciprocable tierewith, means engaging said cam bar and operated thereby to adjust the spacing between said one pulley and said work piece support, means actuated by carriage movement toward the ends of its stroke to reverse the movement thereof, and means simultaneously to index the work piece for feed transverse to the direction of reciprocation of said carriage.

10. In an abrasive grinding machine for grinding the exterior surface of a tube to produce a tube of desired wall thickness, a mandrel rigidly supported at one end over which the tube is adapted to be passed, said mandrel at its unsupported end having a roller having substantially point contact with a part of the tube inside wall, a carriage movable toward and from said mandrel on a path substantially parallel to the mandrel axis, transverse trunnions on said carriage and a barrel supported thereby, means on the barrel for securing thereto one end of the tube to be ground, the axis of the tube being substantially in alignment with mandrel to pass thereover, said trunnions enabling freedom of tilt to said tube, whereby the tube is supported by said trunnions and by said mandrel roller, and abrasive grinding means adjustable to engage the outer wall of said tube at a point thereon substantially directly opposite said mandrel roller.

11. In an abrasive grinding machine for grinding the exterior surface of a tube to produce a tube of desired wall thickness, a mandrel rigidly supported at one end over which the tube is adapted to be passed, said mandrel at its unsupported end having a roller having substantially point contact with a part of the tube inside Wall, a carriage movable toward and from said mandrel on a path substantially parallel to the mandrel axis, transverse trunnions on said carriage and a barrel supported thereby, means on the barrel for securing thereto one end of the tube to be ground, the axis of the tube being substantially in alignment with mandrel to pass thereover, said trunnions enabling freedom of tilt to said tube, whereby the tube is supported by said trunnions and by said mandrel roller, abrasive grinding means adjustable to engage the outer wall of said tube at a point thereon substantially directly opposite said mandrel roller, and means to adjust the spacing between said grinding means and said mandrel roller.

12. In an abrasive grinding machine for grinding the exterior surface of a tube to produce a tube of desired wall thickness, a mandrel rigidly supported at one end over which the tube is adapted to be passed, said mandrel at its unsupported end having a roller having substantially point contact with a part of the tube inside wall, a carriage movable toward and from said mandrel on a path substantially parallel to the mandrel axis, transverse trunnions on said carriage and a barrel supported thereby, means on the barrel for securing thereto one end of the tube to be ground, the axis of the tube being substantially in alignment with the mandrel to pass thereover, said trunnions enabling freedom of tilt to said tube, whereby the tube is supported by said trunnions and by said mandrel roller, abrasive grinding means adjustable to engage the outer wall of said tube at a point thereon substantially directly opposite said mandrel roller, and means to adjust the spacing between said grinding means and said mandrel roller, said latter means including a cam bar secured to said carriage and movable therewith.

13. In an abrasive grinding machine for grinding the exterior surface of a tube to produce a tube of desired wall thickness, at mandrel rigidly supported at one end over which the tube is adapted to be passed, said mandrel at its unsupported end having a roller having substantially point contact with a part of the tube inside wall, a carriage movable toward and from said mandrel on a path substantially parallel to the mandrel axis, transverse trunnions on said carriage and a barrel supported thereby, means on the barrel for securing thereto one end of the tube to be ground, the axis of the tube being substantially in alignment with the mandrel to pass thereover, said trunnions enabling freedom of tilt to said tube, whereby the tube is supported by said trunions and by said mandrel roller, abrasive grinding means adjustable to engage the outer wall of said tube at a point thereon substantially directly opposite said mandrel roller, and means to adjust the spacing between said grinding means and said mandrel roller and means to feed said carriage toward and from said mandrel.

14. In an abrasive grinding machine for grinding the exterior surface of a tube to produce a tube of desired wall thickness, a mandrel rigidly supported at one end over which the tube is adapted to be passed, said mandrel at its unsupported end having a roller having substantially point contact with a part of the tube inside wall, a carriage movable toward and from said mandrel on a path substantially parallel to the mandrel axis, transverse trunnions on said carriage and a barrel supported thereby, means on the barrel for securing thereto one end of the tube to be ground, the axis of the tube being substantially in alignment with mandrel to pass thereover, said trunions enabling freedom of tilt to said tube, whereby the tube is supported by said trunnions and by said mandrel roller, and abrasive grinding means adjustable to engage the outer wall of said tube at a point thereon substantially directly opposite said mandrel roller, said barrel including a member extending from said trunnions in a direction opposite from said tube, and counterweights on said member adjustable substantially to balance said tube about said trunions whereby the pressure exerted by said tube on said mandrel roller is minimized and whereby the droop of said mandrel from its support is substantially uniform.

15. In a machine for grinding or polishing one surface of a tube to produce a surface finish thereon, a member grigidly supported and having a roller upon which one surface of a tubular work piece is adapted to bear, a carriage movable toward and away from said roller having the tubular work piece tiltably carried thereby, the work piece being supported by said carriage and by said roller, and abrasive means adjustable to engage the other wall of said work piece at a point thereon substantially directly opposite said supporting roller.

16. In a machine for grinding or polishing one surface of a tube to produce a surface finish thereon, a member rigidly supported and having a roller upon which one surface of a tubular work piece is adapted to bear, a carriage movable toward and away from said roller having the tubular work piece tiltably carried thereby, the work piece being supported by said carriage and by said roller, abrasive means adjustable to engage the other wall of said work piece at a point thereon substantially directly opposite said supporting roller, and means to adjust the spacing between said abrasive means and said roller.

17. In a machine for grinding or polishing one surface of a tube to produce a surface finish thereon, a member rigidly supported and having a roller upon which one surface of a tubular work piece is adapted to bear, a carriage movable toward and away from said roller having the tubular work piece tiltably carried thereby, the work piece being supported by said carriage and by said roller,

abrasive means adjustable to engage the other wall of said work piece at a point thereon substantially directly opposite said supporting roller, and means to adjust the spacing between said abrasive means and said roller, said latter means including a cam bar secured to the carriage and movable therewith.

18. In a metal-removing machine comprising a reciprocable workpiece carriage and a rotary metal-removing element, said element rotating on an axis transverse to the general direction of reciprocation of said carriage, said element being adjustable as to position to engage a workpiece, means to secure said workpiece flexibly to said carriage for reciprocation therewith, a support for the workpiece lying on the opposite side thereof from said element and having substantially point contact with the workpiece, a cam secured to said carriage and reciprocable therewith, and means engaging said cam and operated thereby to adjust the spacing between said element and said workpiece support.

References Cited in the file of this patent UNITED STATES PATENTS