US2257118A

US2257118A - Abrading apparatus

Info

Publication number: US2257118A
Application number: US154485A
Authority: US
Inventors: Robert B Huyett
Original assignee: Pangborn Corp
Current assignee: Pangborn Corp
Priority date: 1937-07-19
Filing date: 1937-07-19
Publication date: 1941-09-30
Anticipated expiration: 1958-09-30

Description

Sept. 30, 1941. R. B. HuYET'r ABRADING APPARATUS Filed July 19, 195'? 4 Sheets-Sheet Sept. 30, 1941. R. B. HUYETT ABRADING APPARATUS Filed July 19, 1937 4 Sheets-Sheet 2 Sept. 30, 1941. R. B. HuYET-r ABRADING APPARATUS Filed' July 19, 1957 4 Sheets-Sheet 3 Sept 30, 1941- R. B. HuYE'r-r 2,257,118

ABRADING APPARATUS Filed July 19, 1957 4 Sheets-Sheet 4 /ggg'fappuer has@ A93 /64/ l Rez/ense can@ 0 A99 205 w flamme /z 0 Patented Sept. 30, 1941 ABRADING APPARATUS Robert B. Huyett, Hagerstown, Md., assignor to Pangborn Corporation, Hagerstown, Md., a co1'- poration of Maryland Application July 19, 1937, Serial No. 154,485

17 Claims.

The present invention relates to abrading apparatus of the general character wherein castings or other articles are subjected to the action of an abrasive blast and cleaned of adhering moulding sand, scale and the like, and it is particularly concerned with apparatus wherein a high speed throwing wheel is employed to project the blast stream against the work.

By reason of the relative massiveness of throwing Wheels and their necessary adjuncts it has been the practice to bring the Work to the blasting apparatus and manipulate it in the blast stream to expose all of its surfaces and clean the entire article. With heavier articles which do not lend themselves readily to manipulation in the blast stream it has been the practice heretofore to mount the article on a truck, push it into a blast room and clean it with an air blast nozzle. The article is then turned over to clean the underside thereof.

The invention aims to provide an apparatus utilizing one or more blast wheels, together with means conveying relatively massive articles of work to the apparatus and mechanism for causing the blast wheels to traverse the article and efliciently clean all of the exposed surfaces thereof, thereby doing away with hand labor and air blast nozzles.

Another object it is to provide a machine for cleaning relatively heavy articles of Work which will cause at least one blast stream to progressively move along the work and clean a path therealong, and having means for causing said blast stream to clean another path adjacent the first path, and the machine being operable to repeat the cycle until the article of work is entirely cleaned. I

Another important object is to provide an abrading apparatus embodying one or more blast wheels mounted on a carriage for causing blast streams to traverse the work and having means for varying the speed at which the streams traverse the work, whereby a part or parts of the work can be subjected to a more prolonged and hence more intense cleaning action than other parts.

A further object is to provide a travelling carriage having blasting apparatus thereon and adapted to travel in a predetermined direction, together with a work support and a Work pushing mechanism mounted for movement in a direction substantially normal to the direction of travel of the carriage and operable to propel the work one or more steps at a time over the work support to subject a fresh area thereof to the action of the blast as the carriage travels back and forth in its path.

Another object is to provide an apparatus ernbodying a work support and having a carriage mounted for movement in a substantially horizontal plane above the support and having one or more blast devices for directing astream of abrasive at an inclination to the plane of travel of the carriage whereby the sides as well as the top of the work are subjected to an abrading action.

It is a further object to devise an abrading apparatus embodying a Work support, a travelling carriage above the work support and adapted to travel in a path along the Work to be cleaned and direct at least one blast stream thereupon, and a pusher operable to automatically move the work a predetermined distance in a direction substantially normal to the path of said carriage each time or plurality of timesV the carriage moves throughout its range of travel.

A further object is to provide an abrading apparatus having a, travelling carriage upon which abrasive projecting means are mounted and having means for conveying abrasive from a stationary abrasive supply to said carriage;

Further objects of the invention will become apparent as the .specification proceeds in connection with the annexed drawings, and from the appended claims.

In the drawings: n

Figure l is a side elevational View of a machine embodying the invention and parts thereof have been broken away to more clearly illustrate the structure involved.

Figure 2 is a front elevational View of the machine illustrated in Figure 1 and parts thereof have also been broken away to more clearly illustrate the structure.

Figure 3 is a fragmental front elevational View of the machine of Figure 2, and illustrates the upper part of the machine that is not shown in Figure 2.

Figure 4 is a fragmental side elevational view of the upper portion of the machine of Figure 1 and illustrates the structure not shown in that iigure.

Figure 5 is an enlarged side elevational view of the automatic valve for controlling the abrasive flow.

Figure 6 is a diagrammatic top plan View of the machine and illustrates schematically the various switches for controlling the different motors of the apparatus.

Figure 6A is a top plan View on an enlarged scale of the stop cams shown in Figure 6.

' opening work.

FigureV 9 is a diagrammatic View of the wheels shown in Figure 8, but shows a side View of the wheels.

Figure 10 is a View similar tov Figure 9, but

illustrates the action of the blast stream when the wheels are rotated in directions opposite to that of Figure 9. l

With continued reference to the drawings, wherein likereference characters have been employed to designate like parts throughout the several views thereof, broadly the device comprises a table A upon which the work is placed, which is mounted for rotation about a vertical axis to bring the work into a cabinet B; a carriage C upon which a pair of blast Wheels D1 and D2 are mounted, the carriage being mounted for movement in a horizontal plane to allow the blast streams to progressively impinge upon the work from one end to the other thereof.

Abrasive is fed to the wheels by distributing mechanism designated generally as E and an abrasive recovering 'and purifying apparatus designated as F is employed to pick up the spent abrasive,Y purify it and Vreturn it to the blast wheels. As the wheels are reciprocated back and forth over the work contained in cabinet B, a pusher designated as Gr is employed to periodically slide the work overthe table surface in a direction substantially normal to the direction of carriage travel for presenting a fresh area of the work to the action of the blast streams.

Work table and cabinetV Referring to Figures 1 and `2, cabinet B is provided with a top wall I having an elongated II therein through which the blast streams are projected. The cabinet is also provided with side walls and a rear wall I2, the front of the cabinet being open to permit the work to be carried into and out of the housing.

TableA is journaled for rotation about a substantially vertical axis on a pedestal I3 and is made up of a pair of long girders I4 which each carry longitudinal work supporting rails I5. A pair of cross beams IB bridge girders I4 and connect the latter to a hub structure I 'I which is journaled on pedestal I3. Table A is also provided with an upwardly extending central structure I8 which terminates inV a shaft portion I9 whichY in turn is journaled in the bearing 2|. Bearing 2! is carried by a pair of cross members 22 which in turn are supported by a pair of longitudinal beams Y23 and 24 which extend across the front of the machine and are supported in any suitable manner.

Work may accordingly be placed upon rails I5 in the'front of the machine and the table rotated aY half revolution to carry the work into the interior of the cabinet B.

f In Figure 6 there is diagrammatically illustratedrone form of means for rotating table A the machine which supports one of the tracks for carriage C, and thev latter will now be described.

Blast wheel carriage Carriage C is provided with four wheels 26 which ride upon a pair of rails 21 and 28 supported upon beams 24 and 25, respectively. C'arriage C is made up of

side plates

29 and 3| which are interconnected by a pair of

bed plates

32 and 33 which support the abrasive throwing wheels. The upper edges of

side plates

29 and 3| are bridged by a pair of

beams

34 and 35 which in turn support a pair of further beams 36 and 31.

Abrasive wheels D1 and D2 are of the identical construction and hence only one of them will be described and similar reference characters will be applied to both of them. Each wheel is provided with a base 40 which is secured to its

respective bed plate

32 and 33. The wheel properv is designated as 4I and is seen diagrammatically in Figure '7. Wheel or rotor 4I carries a plurality of blades 42 which terminate short of the center of rotation to provide a central space in which a feed chamber 43, having 'a dischargeV opening 44, is disposed.y Mounted for rotation with rotor'4I is a bladed impeller 45 having a hollow center into which the abrasive is introduced. Cage 43 is mounted for angular adjustment whereby the discharge stream from the Wheel may be placed in any desired direction.

Rotor 4I is mounted upon a shaft 41 which is journaled on base 4I) and is providedwith a sheave 48. An electric motor 49 is also mounted upon base and is provided with a driving sheave 5I which is connected to sheave 4l by a plurality of V-belts 52 known as Texrope drive. The wheel is enclosed by a housing 53 and extending through an opening in the hcusingis an abrasive supply pipe 55 which Vextends into cage 43 and communicates with the interior of impeller 45.

Suitable openings are provided in

bases

32 and 33 to allow the wheels to project therewhich may, if desired, be manually rotated. In

througlhand the bottom of carriage C is likewise open so that thel abrasive streams issuing therefrom may freely pass downwardly upon the work supported upon table A.

Although a four-bladed wheel is shown'it is to be understood that if desired a wheel having more or less than four blades may be used or in fact any other suitable type of apparatus that will impart an abrading velocity to the abrasive.

Carriage Cl may be reciprocated by any suitable means but I preferably employ a motor 56 which is connected to the input Side of a gear boX 5l having an output sprocket 58. A chain 59 passes over sprocket 58 and Vmeshes with a larger sprocket 6I mounted on a shaft 62 journaled on beam 23. shaft 62 and a cable 55 is secured thereto and makes a plurality'of turns therearound. One end of cable 65 is connected to one end of car-` riage C at V66 and the other end passes over a pulley (not shown) and is connected to thefother Y end of carriage C atY 61. It is accordingly apparent that rotation of shaft 52 in a clockwise direction will cause carriage C to move to the right in Figure 2, and counterclockwise rotation will cause the carriage to move to th-e left.

Abrasive feeding mechanism Abrasive is supplied to the wheels Dr and Dz as follows. A trough-shaped structure 69 is A drum 64 is secured to mounted above the wheel on carriage C, and'is supported at its front end by a plate 1| connected to beam 31, and at its rear end it is connected to beam 35 by means of a plate 12. The mid-portion of the structure is connected to side plate 3| by means of an upright 13.

A screw conveyor is disposed in trough 69 and extends through either end thereof, and is journaled in

bearings

16 and 11 located exteriorly of trough 69. Mounted on the screw conveyor is a sprocket 19 which carries a chain 8| meshing with a sprocket 82 carried by the output shaft of a speed reducer 83. Speed reducer 83 is driven by motor 84 and the two units are supported on carriage C by means of a pair of plates 85 which provide a bed having a bottom 85. Communicating with the interior of trough 59 are abrasive delivery spouts 81, 88 and 89. Spout 81 is connected to the feed pipe 55 of wheel D2, Whereas spout 88 is connected to feed pipe 55 of wheel D1. Spout 89 is known as an overflow spout or by-pass and communicates with a pipe 9| which is operable to return the abrasive to the abrasive recovery system to be hereinafter described.

f Operation of motor 84 causes feed screw 15 to rotate and advance the abrasive from right to left in Figure l toward feed spouts 81, 88 and 89. A predetermined amount of abrasive is taken by feed spouts 81 and 88 and any excessive abrasive spills into the overow or by-pass spout 89 and is returned to the abrasive recovery system.

Abrasive is introduced into trough 59 by means of a hopper 92 which communicates with an opening 93 in the upper side of trough 59. The

elongated upper edge whereby feed spout 99 may communicate therewith regardless of the reciprocated position of carriage C. Trough 99 is accordingly continuously supplied with abrasive during the reciprocation of the carriage C, and

in view of the comparatively small volumetric capacity of hopper 92, it does not accumulate much abrasive at any time. As a matter of fact, it functions more in the nature of a pipe as it immediately conducts abrasive from. spout 99 to the interior of trough 89. Any suitable means may be employed to conduct electricity to motors 49 and 84 located on carriage C, as for instance, a trolley wire assembly, or a flexible cable having suicient slack in it to permit the carriage to move from one end of its travel to the other.

With reference to Figure 5, spout 99 communicates with a supply hopper I9| to which the abrasive is returned from the abrasive recovering and cleaning system.

A pair of abrasive control valves |82 and |99 are mounted upon a common shaft |94 which is journaled in spout 99. A crank arm |85 is mounted on shaft |84 exteriorly of spout 99 and is provided with an elongated slot |86. A control lever |81 is journaled on a pin |88 carried by a support |99 and carries a pin 5| which engages slot |88. The other end of lever |91 is pivotally connected at l2 to a link |63. The upper end of link ||3 constitutes the armature of a solenoid ||4 which is preferably connected in As Shown in Figure 5, solenoid ||4 is energized thereby holding link ||3 in its raised position, which, through pin and crank holds abrasive valves |82 and |93 in the open position shown in Figure 5, thereby allowing abrasive to pass from hopper |9| through spout 99 to hopper 92. When the circuit is broken in response to shutting down motor 84, solenoid ||4 is deenergized, thereby allowing counter-weight 5 to rock lever |91 oounterclockwise and act upon the walls of slots |06 to rock crank |95 and close the abrasive valves. The abrasive now to hopper v92 and trough 69 is accordingly automatically cut on every time the screw conveyor motor is stopped. In this way the feed of the abrasive to the wheel is quickly stopped as spouts 88 and 81 are comparatively short and do not hold much residual abrasive. Stopping feed screw 15 promptly is advantageous because in that way trough 89 is maintained practically full of ab-rasive so that when motor 84 is again started and valves |92 and |93 are opened, a normal feed of abrasive to the wheels is almost immediately reestablished.

Abrasive recovery system The bottom of housing B, as well as the upper surface of table A are preferably perforated so that the spent abrasive may freely gravitate downwardly into a hopper below the floor level (not shown). This hopper is provided in well known manner with a screw conveyor for conveying the abrasive to one end of the hopper and into the boot of an elevator ||1 which projects below the floor level. Elevator ||1 (Figures 2 and 3) comprise a plurality of buckets I8 mounted upon a belt ||9. Belt |9 passes over a drive pulley |2| in the upper end of theelevator housing and a similar idler pulley in the bottom of the housing. The drive pulley is driven by a sprocket |23, a chain |24, and a sprocket |25. Sprocket |25 is in turn driven by a motor |21 having a sprocket |28, meshing with a chain |29 which also meshes with a sprocket 3| and with a shaft on which sprocket |25 is mounted.

Buckets ||8 discharge into a chute |33, which in turn discharges into a rotatable drum |34.

The abrasive cleaning mechanism may be of any suitable type and it operates to remove molding sand, nails and other extraneous material from the abrasives before it is finally delivered to the clean abrasive supply hopper 8| the nails and other extraneous material being delivered to a chute |45 and then conducted to a waste receptacle |48. The molding sand is discharged into a separate conduit |48 and then conducted to a suitable receptacle |49. A suction connection |41 is provided to carry away fine dust, etc.

Work pusher mechanism After the blast mechanism has made one or more passes over the work, pusher G is operated to advance it a predetermined distance before the work blast stream again traverses it in order to present a fresh area to be cleaned.

- Althoughthe workpusher may assume Yvarious `forms, in the present instance-it is shown as vmade up of a bar |52, which is guided for movement in a horizontal plane by a, plurality of rollers |53, which are rigidly journaled von any suitable elements of the apparatus. Bar |52 is reciprocated by means of a motor |54 which is mounted on a frame part |55. Motor |54 drives aY speed reducer |55 which is provided with a sprocket |56.Y YApinion |51 is journaled below the bar and meshes with ajtoothed rack |58 secured to bar |52. A sprocket |59 is mounted on the shaft carrying pinion |51 and a chain interconnects it with drive sprocket |56. Accordingly, by controlling the circuit of motor |54, bar |52 may be advanced into or retracted from housing B. Bar |52 is provided with a head |59 of suitable -form for engaging the work.

Operation` Assuming that the circuit forY motors 49, 55,

84|V vand V2|) are open, the operator places an artitially to the positionl W1 shown in Figure 1.

'Ihe circuits for motors r|21 and |36 are closed and then the circuits for motors 49, 55 and B6 are closed which causes the following events to take place:

A (1) Abrasive wheels D1 and D2 are started and brought up to speed very quickly.

. (2) Motor 84 drives screw 15 which starts feeding abrasive to the wheels. Y

(3) Solenoid ||4 lifts lever I0] and'opens the abrasive valves |02 and |03, which start the abrasive lowing into hopper 92. Y

(4) Motor 56 starts carriage C to moving to- Ward one end of its direction of travel. i

An interlock is preferably provided so that the Various motors can not be started until table A reaches a predetermined stop position. The circuit also is designedto prevent the table motor 20 from operating until pusher rod *|52 is disposed in its full line retracted position shown in Figure 1.

` With the machine operating as just described, the carriage makes one passover the Work and cleans a part of the top surface or swath of the work piece, and also the side designatedas |1 I. The manner in which the abrasive streams cooperate with each other to clean the work piece is shown in Figures 8v and 9. Referring to Figure 8, wheels D1 and D2 are inclined so ythat the blast streams issuing therefrom converge as shown in Figure 8, so that they almost meet at the surface of the work to be cleaned. Although they could be mounted so as to actually intersect before reaching the work piece a considerable loss of eciency would occur because the Yparticles from the two blast wheels would interfere with each other before striking the work.

In Figure 9 there is illustrated Yone manner in which streams may be adjusted through adjusting cages 43 of wheels D1 and D2. With reference to this figure, the streams'issuing from wheels D1 and D2 are seen to overlap. Their spray an.-

gles X are equal and the angle Y indicated is the area of overlap. In this figure the wheels are mounted so as to rotate toward each other, but if desired theymay be mounted to rotate away from each other as shown in Figure 10. In that figure the spray angles X are the same as before, and the angle of overlap Y is very similar.

Assuming the apparatus is operating as just described, and the carriage has made one passage over the work, when the carriage approachesY the end of its travel, means are preferably providedV for automatically starting motor |54 so as to advance rod |52 one step which causes head |55 of the pusher to engage the work and slide it upon rails |5 into a new position. The carriage f is then automatically reversed and makes a passageover the work in the opposite direction.

The automatic advancing of the pusher each time the carriage makes one or more passes over the Work is continued until the work attains the position indicated as W2 in Figure 1. Whenthe work is in this position it is apparent that the blast streams are operable to clean the side surface of the work designated as |12. After the carriage has made its last passage with the work disposed in the position W2, the motor |54 is reversed to retract rod |52 into the solid line posi` tion shown in FigureY 1, and table A is then rotatedto bring a fresh article of work into the blast chamber and simultaneously remove the cleaned article. the fresh article will preferably have been placed on the other side of the table, while the first article is undergoing cleaning. During the work changing operation the other motors may or may not be stopped as desired, depending upon whether the succeeding article is to be immediately cleaned.

In View of the fact that elongated bodies of large size which this machine is particularly capable of handling, are often of non-uniform section throughout their length or for other reasons require that a more intensive cleaning action be imparted to one portion than another, there is preferably provided means for causing the carriage to move fast during a part of its vtravel and slower during another part of its travel. It is apparent that when the carriage moves at a normal fast rate the work will receive a normal cleaning action, whereas when it moves slowly the work will be more intensively cleaned. The positions at which the transitions from a fast to a slow speed or from a slow speed to ahigh speed occur can be adjusted to adaptthe machine to any particular type of work. The mechanism is alsov adjusted so that this change in speed occurs entirely automatically.

In view of Ythe fact that such electrical equipment as push button stop and start controls, re- Versing switches and interlocking electrical circuits are well known in the art, and as no novelty for them per se is claimed in the present application, the various electrical equipment is but diagrammatically illustrated in FigureG.

With continued reference tol this flgurea simple push button switch |14 is employed to start motor 2B. For stopping motor 25 there is shown aswitch |15 embodying a pair of contacts |16 and |11 mounted on a plunger |18. Contact |16 controls the pusher motor and is operable to start the pusher when it is closed. Contact |11 is operable to open the circuits of the motor 20 and stop the table, and in order to render the operation automatic, contacts |16 and |11 are provided It is of course understood that' rod 205 whlch'cooperates with a cam 200 on mem-` with a plunger |18 which cooperates with a pair of fingers |19 and |8| provided on the table.

In order to make sure that the table will not be operated until pusher G has been retracted, a second interlocking safety switch |83 is provided and it embodies a pair of contacts |84 and |85 which are in series with the circuit of motor 2E so that the latter cannot be started until switch |83 is operated to close contacts |94 and |85.

In order to more clearly illustrate the operations involved, I have illustrated the pusher G as having a portion |86 upon which various parts of the electrical system are mounted. Mounted on the rear portion of member |86 is a'cam |81 which cooperates with the operating rod |88 of switch |33. As seen in Figure 6, cam portion |81 of pusher G holds switch rod |88 in a position to close the circuit between contacts |84 and |85, and thereby make it possible to close the table motor circuit by operating push button |115. As cam |81 will only engage rod |88 when pusher G is in its rearmost position, it is apparent that the table motor circuit can not be closed until the pusher occupies this position. I have also illustrated a switch |80 which controls the wheel car riage motor 50 and solenoid ||i| and motor |84. If desired, the circuit for motors lS may also be controlled by this same switch.

Also mounted on member |85 is a stop switch |92 for motor |54 and it embodies a plunger |93 which cooperates with a plurality of stationary but adjustable supported cam members |94. Members |90 are adjustably mounted on a plate |95 by means of screws |9ia. Plate |95 is in turn adjustably suported on any suitable part of the machine by a pair of screws |9511; The slots in plates IM and |95 permit the plates to be adjusted lengthwise of the path of travel of the pusher so that they may actuate switch |93 in any desired manner. As the pusher is advanced and plunger |93 strikes the first cam |94, it breaks the pusher motor circuit and movement of the pusher ceases. In order to restart the pusher and also reverse the carriage when it attains the end of its travel, I have provided a combination switch at each end of the apparatus. These switches are designated as switches |31. They each embody a pair of contact arms |99 and |99 and a common operating rod 20| carrying a finger 202 at the end thereof. Contact |98 controls the circuit of pusher motor |54, while Contact |99 controls the reversing circuit of carriage motor 55.

Cooperating with switches |91 are a pair of cams 203 which are carried by any suitable part of the carriage; and accordingly, when carriage C reaches one end of its travel one of the cams 203 will strike one of the switch rods 28| so as to close the pusher motor circuit and also reverse the circuit for carriage motor 56. When the pusher has advanced one step, one of the cam faces |94 will actuate switch |93 to again stop the pusher motor as previously described. The motors 56 and |54 are preferably provided with magnetic brakes so that they will promptly come to rest when their circuits are broken.

When the pusher has attained the end of its travel, it is automatically stopped and reversed by means of a switch 2011y having an operating ber |86.

In order to provide for the automatic transition from a slow carriage speed to a fast carriage speed or vice versa, I have provided intermediate switches 208 which are operable to change the motor connections to secure the desired speed. Each switch 208 is provided with an operating plunger 209 which cooperates with cam 203 whereby during a predetermined stage of carriage movement one of the switches 208 will be thrown to reduce or increase the speed of carriage motor 5%, and thereby vary the carriage speed auto-v matically. Switches 208 are preferably mounted for adjustment longitudinally of the carriagey path, in order that the point or points at which a change in the carriage speed will occur can be adjustably varied to `suit the particular type of work operated upon. Also, if desired, additional switches similar to switches 208 may be inter-` posed in the path of carriage travel for introducing more than two speed changes for each stroke of the carriage.

For instance, if the work piece must be intensively cleaned adjacent the ends thereof, the

switches are so adjusted that the carriage will` initially undergo a slow movement; one of the cams 263 will then strike one of the switches 298 to cause motor 55 to accelerate, cause the carriage to undergo a more rapid intermediate stage of movement; the other cam 293 will then strike` the other switch 268 so as to again restore the slow speed of carriage movement so as to cause the blast streams to intensively clean the other end of the work piece operated upon. If desired,

the switches may be adjusted to produce the opposite effect; namely, to cause the carriage to move fast over the ends of the work and to undergo a slower movement intermediate the ends of the work so as to subject the mid-portion of the work to an intensive cleaning action.

As previously indicated, thecircuit for the' wheel motors 09 is preferably independent of the other circuit so that they may be started bypush buttons and be operated continjuously except when the machine is shut down.

The form of operation of carriage C and pusher G will vary depending upon the nature of the work handled by the machine. For instance, if the work requires a fairly uniform cleaning action over its entire surface, the pusher will be operated to advance the work one step each time the carriage reaches the end of its travel. As previously pointed out, if the w-ork possesses dirty spots or areas requiring a more intensive blasting action switches 208 are so adjusted as to cause the carriage to travel slower in those regions and thereby allow the blast streams to act for a longer time upon those areas.

If desired, additional wheels may be mounted upon carriage C and be disposed at various inclinations to meet the particular working condition involved. A

I have shown and prefer to employ a conveyor that assumes the form of a table, because it possesses two Zones-permitting one to be loaded while the other is in the blast cabinetbut it is to be understood that if desired other forms of conveyors may be used without departing from the spirit of my invention.

The invention may be embodied in other specic forms without departing from the spirit or essential characteristics thereof, The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the

' uponY said work, said mechanisms each embodying a rotor mounted for rotation about an axis inclined with respect to the Yplane of movement of said carriage and operable to discharge a blast stream of abrasive downwardly upon said Work, said rotor axes being disposed at opposite inclinations with respect to said plane of movement of said carriage' for directing said abrasive blastV streams against the ends as well as the upper surfaces of said work,'and means for moving said carriage for causing said blast streams to traverse said Work.

2. The abrading apparatus described in claim l, wherein said rotor axes are so inclinedv as to cause said abrasive blastV streams to converge but are so'directe'd as to 'strike the work before they become suiliciently proximate to each other to intermingle.

' 3. The abrading apparatus described in claim 1, wherein said rotor axes are disposed in vertical parallel planes which extend in the direction of movement of said carriage.

4. In an abrading apparatus, a work support upon which articles of work may rest, a carriage disposed above said work support and mounted Y for movement in a substantiallyV horizontal plane,

5. The abrading apparatus described in claim 4;

wherein said pusher means embodies means for moves, for varying the abrading action upon the work. Y v

6. The abrading apparatus described in claim 4, wherein saidpusher means embodies `an lelectric motor, and control means are provided Vfor automatically energizing said motor when said carriage reaches one end of its movement.

f7. The abrading apparatus described in jclaim l, wherein said pusher means embodies control means coordinated with saidV carriage for 'automat'ically causing said pusher to ksuccessively advance said work each time said carriage attains one'end of its movement. '.8. In an abrading apparatus, ahousing providing a blasting zone, a conveyor providing an upwardly facing surface upon which articles of work maybe placed, said 'conveyor being movable to bring articles of work into and out -of said blasting zone, a carriage mounted for movement in a substantially horizontal plane Aabove said conveyor and having means `for directing a blast stream down upon articles of Work supported on said conveyor, pusher means for periodically moving said work in a direction substantially normal to the direction of movement of said carriage to expose different areas thereof to the action of said blast stream as said carriage moves from one end of its travel to the other, and control means for preventing said pusher means from operating until said conveyor is disposed in lapredetermined blasting position.

9. The abrading apparatus described in claim 8,

wherein control means are also provided for preventing said conveyor from operating until said pusher means is disposed in retracted condition.

10. The abrading apparatus described in claim 8, wherein said pusher means comprises a bar element mounted for reciprocaticn into and out of said blasting zone `in a direction substantially normal to the path of movement of said carriage and is operable to directly engage said Work.

1l. 'I'he abrading apparatus described in'claim 8, wherein Vsaid conveyor comprises a table mounted for rotation about a substantially Vertical axis.

12. In an abrading apparatus, a Vcarriage Y mounted for reciprocation in a substantially horizontal path, at least one abrasive propelling rotor mounted for rotation on said carriage, a motor mounted on-said carriage and connected to said vvariably adjusting the distance through which it rotor, an abrasive conveying mechanism forsupplyingv said rotor with abrasive, and a second motor mounted on said carriage and drivingly connected to said conveyor.

13. The abrading apparatus described in claimV 12, wherein a hopper is alsomounted on said carriage, the lowerfend of said hopper communicating with said conveyor andthe upper end of said hopper providing an upwardly facing-opening which is elongated in the direction of travel of said carriage, thereby adapting it to be fed from a stationarily supported abrasive feed conduit.

14. The abrading apparatus described in claim 12, wherein said first and second motors areengaged by a commonl electrical circuit, whereby,Y e when said rotor is stopped said conveyor will automatically cease feeding abrasive thereto. v

` 15. The abrading apparatus described in claim 12, wherein said conveyor is supplied with abrasive through a solenoid controlled valve, and said first and second motors and said valve Vare energized by a common electrical circuits whereby,

when said circuit is broken to stop said rotor, the' flow of abrasive is automatically stopped.

16. In anabrading machine, a work support upon which articles of work may rest, a carriage mounted for reciprocatory movement above said work support, at least one abrasive propelling wheel mounted on said carriage and having a prime mover for driving it mounted on said carriage, and means for reciprocating said carriage for causingsaid abrasive propelling wheel to di- Y rect a stream of abrasive upon said work, throughout the length of said work, said means for reciprocating said carriage embodying automatically operable control means for causing said carriage to travel at a slower speed during at least one portion of its stroke, for causing said work to be subjected to a greater abrading action over part of its length.

17. In an abrading 'machina' a work SulODQrt upon'which articles of work Vmay rest, a carriage mounted for reciprocatory movement above said work support, at least one abrasive propelling wheel mounted on said carriage and having a prime mover for driving vit mounted on said carriage, and means for reciprocating said carriage for causing said abrasive propelling Wheel to direct a stream of abrasive upon said Work, throughout the length of said Work, said abrasive propelling wheel being operable to discharge abrasive substantially solely downwardly in a plane disposed normal to the axis of rotation of n said wheel, said wheel being mounted on said carriage with its axis inclined to the plane of travel of said carriage, whereby said discharge therefrom is so inclined as to abrade the ends as 5 well as the upper surfaces of the article of Work.

R. B. HUYETT.