US3503153A - Bee-line flow finishing apparatus - Google Patents

Description

March 1970 HISAMINE KOBAYASHI 3,503,153

BEE-LINE FLOW FINISHING APPARATUS Original Filed March 21, 1967 3 Sheets-Sheet 1 March 1970 HISAMINE KOBAYASHl 3,50

BEE-LINE FLOW FINISHING APPARATUS Original Filed March 21, 1967 3 Sheets-Sheet 2 [lllll March 31, 1970 HISAMINE KOBAYASHI 3,503,153

BEE-LINE FLOW FINISHING APPARATUS Original Filed March 21, 1967 3 Sheets-Sheet 3 3,503,153 BEE-LINE FLOW FlNISHlNG APPARATUS Hisamine Kobayashi, 13, 3-chome, Kikuzono-cho, Showa-ku, Nagoya, Japan Original application Mar. 21, 1967, Ser. No. 624,874. Divided and this application Jan. 22, 1969, Ser. No. 807,152 Claims priority, application Japan, June 18, 1966, il/39,505, ll/39,506, 41/139,507 Int. Cl. 1324b 31/00 US. Cl. 51-17 6 Claims ABSTRACT OF THE DISCLOSURE A carrier device of U-shaped endless belt type composed of a durable wire net is tightly spanned between a pair of vertical belt wheels and its bottom is supported by a plurality of bearing rollers while each of its side walls is supported by a plurality of guide rollers except for the ranges of the belt wheels. A quantity of abrasives is loaded in the form of a loose layer into the device. One of the belt wheels is driven to rotate the device and therefore the abrasive layer is moved in one direction in the horizontal plane. Workpieces are moved one after another in counterflow relation in either or both of the rectilinear portions of the traveling abrasive layer. If desired, the workpieces may push against the surface of the rectilinear abrasive portion. Also a layer of abrasives can be rotated in a vertical plane. A carrier device of channelled endless belt type composed of a flexible material is tightly spanned between a pair of horizontal belt wheels such that the major part of its upper rectilinear section formed between the belt wheels is of a substantially U-shaped cross section confined by a plurality of roller sets such as above described for purpose of surface finishing while the remaining section of the devices has a closed cross sectional profile by having a plural sets of four rollers disposed on four sides of the device excepting that the inside rollers are omitted in the range of each belt wheel. Further a pair of channelled endless belts can be juxtaposed into an X-shaped arrangement in the respective vertical planes and be rotated in the opposite directions. A layer of abrasives is formed in the ascending upper rectilinear section of each traveling belt and is transferred from its top end onto the other ascending rectilinear belt section through a transfer chute. Workpieces are successively passed through one of the rectilinear streams of the abrasive layer from its upper end to its lower end and then transferred to the other rectilinear stream with their orientation remaining unchanged followed by the similar passage through the other stream. Alternatively both rectilinear streams may be utilized for separate finishing operations. Preferably the speed of the workpieces relative to the rectilinear abrasive stream ranges from 70 to 500 meters per minute and the finishing time ranges from 10 seconds to 15 minutes. The rectilinear abrasive stream has a length of from less than 1 to more than 10 meters. The abrasives may be of either dry or wet type.

This application is a division of my copending application Ser. No. 624,874, filed Mar. 21, 1967, now Patent No. 3,449,871.

This invention relates to improvements in the surface finishing technique and more particularly to a method of automatically surface-finishing workpieces with a rectilinear stream of loose abrasives and an apparatus for carrying out such a method.

The conventional type of surface finishing methods, even though they are of the rotary, vibratory or cen- United States Patent ICC trifugally gyratory barrel type, has been mostly subject to various limitations due to the conditions for flowing a mass Within a finishing barrel which conditions depend upon the configuration of the barrel and the type of drive therefor involved. By the term mass is meant a mixture of workpieces to be finished, abrasives and other materials charged in a finishing barrel. Those limitations lead to other limitations as to the configuration and size of the workpieces and to their amount charged in each barrel also determined by the configuration of the barrel and the type of drive therefor. Accordingly, the conventional methods have successfully surface finished workpieces relatively small in size and symmetrical in configuration but they could scarcely succeed with both large-sized long workpieces and the special portions of small-sized workpieces. For example, such methods could not surface finish mufflers for use on autobicycles, bumpers, radiator grilles and decorative straps for use in automobiles etc.

It is, accordingly, an object of the invention to provide a new and improved method of continuously and automatically effecting surface finishing of workpieces regardless of their size and configuration and especially of largesized, long workpieces.

It is another object of the invention to provide a new and improved method of automatically effecting surface finishing of workpieces on the basis of production line.

Briefly, the invention accomplishes the above cited objects by the provision of a method of surface finishing workpieces, comprising the steps of establishing a stream of loose abrasives circulating at least partly along a rectilinear path while that portion of the abrasive stream moving along the rectilinear path has a substantially uniform density and a predetermined cross sectional profile, and moving the workpieces, one after another, relative to the rectilinear portion of the abrasives stream at a predetermined relative speed in a direction opposite to the direction of the stream while maintaining the workpieces in surface-finishing engagement with the rectilinear stream portion.

The speed of the workpieces relative to the rectilinear stream portion may preferably range from to 500 meters per minute.

The invention also contemplates to provide a new and improved apparatus for carrying out the surface finishing method as above outlined. The apparatus comprises carrier means of channelled endless belt type composed of a flexible durable material, a pair of driving belt wheel and a turning belt wheel for spanning the carrier means in tensioned state to form a pair of parallel rectilinear sections therebetween, a quantity of abrasives loosely and uniformly distributed in the form of a layer within the carrier means, means for maintaining a substantially U- shaped cross section of at least one of said rectilinear sections of said carrier means, and means for holding and driving the workpieces one after another to move at a predetermined relative speed them in a direction opposite to a direction a rectilinear stream portion of the abrasive layer in the U-shaped rectilinear section of the carrier means driven by the driving belt wheel while maintaining the workpieces in surface-finishing engagement with the rectilinear stream portion.

In a preferred embodiment, the carrier device composed of a flexible durable wire net may be spanned in tensioned state between a pair of vertical belt wheels and has a bottom supported by a plurality of bearing rollers and both side walls each supported by guide rollers except for the range of each belt wheel whereby the cross section of the device is maintained a substantially U-shaped. Thus the carrier device is rotatable in one direction in a horizontal plane to establish a pair of rectilinear stream portions of an abrasive layer loaded in the device for purpose of surface finishing.

In order to surface finish relatively small-sized workpieces, a carrier device of channelled endless belt type may be rotated in tensioned state in a vertical plane between a pair of horizontal belt wheels. The major part of the upper rectilinear section of the carrier device may be supported a plural sets of rollers such as above described to have a substantially U-shaped cross. section. In order to prevent a layer of abrasive formed in the carrier device from falling down from the remaining section of the device, a plural sets of four rollers are disposed on four sides of the remaining section of the device except that the inside rollers are omitted in the range of each belt wheel whereby the remaining device section has a cross sectional profile completely closed.

For long workpieces, two pairs of carrier devices of channelled endless belt type may juxtaposed in tensioned state in the respective vertical planes to form an X-shaped arrangement by having two pairs of belt wheels engaging the same respectively and rotated in the opposite directions. The carrier device may advantageously have both side walls each comprising a plurality of outwardly flared plates alternating similar plates. These outwardly flared plates overlap each other when the associated portion of the device is traveling along a rectilinear path between the associated pair of belt wheels. A layer of abrasive is formed on the ascending upper rectilinear section of each device and transferred from the upper end thereof onto the ascending upper rectilinear section of the other device through a transfer chute. Workpieces can be successively passed through an ascending stream portion of the abrasive layer on the upper rectilinear section of each device.

The invention as to its organization and its mode of operation as well as other objects and advantages thereof will become more readily apparent from the following detailed description taken in conjunctiton with the accompanying drawings in which:

FIG. 1 is a fragmental plan view of a surface finishing apparatus constructed in accordance with the principles of the invention with parts removed for purpose of illustration;

FIG. 2 is a fragmental side elevational view of the apparatus illustrated in FIG. 1 with parts removed for purpose of simplification and with parts broken away for the purpose of illustrating a position of a workpiece relative to a stream of loose abrasive;

FIG. 3 is a sectional view taken along the line III-III of FIG. 2 and illustrating a roller set for the apparatus;

FIG. 4 is a fragmental side elevational View of a modification of the invention with parts removed for purpose of simplification and with parts broken away for the purpose of illustrating a position of a workpiece;

FIG. 5 is a fragmental plan view of the apparatus illustrated in FIG. 4 with parts removed for purpose of simplification;

FIG. 6 is a sectional view taken along the line VIVI of FIG. 4 and illustrating a roller set for the apparatus;

FIG. 7 is a view similar to FIG. 6 and illustrating a section taken along the line VIIVII of FIG. 4;

FIG. 8 is a view similar to FIG. 6 and illustrating a section taken along the line VIII-VIII of FIG. 4;

FIG. 9 is a fragmental diagrammatic view in side elevation, of another modification of the invention with parts removed for purpose of simplification and with parts broken away for the purpose of illustrating a posititon of a workpiece relative to a stream of loose abrasive;

FIG. 10 is a front view of the apparatus illustrated in FIG. 9;

FIG. 11 is a fragmental side elevational view, in enlarged scale of an upper end portion of a carrier device illustrated in FIG. 9

FIG. 12 is a fragmentay sectional view taken along the line XII-XII of FIG. 11; and

FIG. 13 is a view similar to FIG. 12 but illustrating a modification.

Quite unlike the commonly accepted concept the invention is based upon the concept that workpieces either push against a surface of a rectilinear stream of loose abrasive moving at a predetermined speed in one direction or move through that stream at a predetermined speed in the opposite direction while they are maintained immersed into the stream.

Referring now to FIGS. 1 to 3 inclusive, there is illustrated a surface finishing apparatus of vertical recirculation type constructed in accordance with the principles of the invention. An arrangement illustrated is of a medium capability and comprises a .pair of vertical belt wheels 10 and 12 vertically disposed at any desired interval determined for the particular application with one of the belt wheels, for example, the wheel 10 serving as a driving wheel. Between the belt wheels 10 and 12 there is spanned in tensioned state a carrier device of channelled endless belt type generally designated by the references numeral 14. The carrier device 14 is substantially of a U-shaped cross section and composed of any suitable expandable, durable material. Suitable examples of such a material involve a wire net made of a stainless wire or the like into an expandable structure with minute mesh openings and such a wire net having bonded on the internal surface a steel wire fabric coated with any suitable plastic.

In order to support and guide the U-shaped carrier device 14 even during its movement the bottom of the U is supported and guided by a plurality of bearing rollers 16 substantially coextensive with the same and disposed at substantially equal intervals throughout the length. Disposed on the outer side wall of the device 14 throughout its length is one external guide roller 18 coextensive with the leg of the U in a vertical plane passing through the longitudinal axis of each bearing roller 16 while one internal guide roller 20 similar to the roller 18 is disposed on the internal side wall and directly opposing to each roller 18 except for the ranges of each belt wheel 10 or 12. One set of these three rollers 16, 18 and 20 is diagrammatically illustrated in FIG. 3.

Thus it will be appreciated that the carrier device 14 is positioned in a space confined by the rollers 16, 18 and 20.

Then a quantity of abrasives 22 is loosely and uniformly loaded in the interior of the carrier device 14 throughout its length and up to any suitable level for example, up to approximately two thirds the depth of the device to form a layer of abrasive in a closed loop.

It will be appreciated that the abrasives may be of the dry or wet type or in the form of a paste. If desired, they may contain any suitable liquid such as water, a surface active agent, a glossing material etc. The abrasives may be in the form of a powder or a granule or a cake having any suitable shape such as a spherical, a pyramidal, a rhombohedral, an ellipsoidal or a cylindrical shape or the like. They may have a mean diameter ranging from 0.01 mm. to the order of 50 mm. dependent upon the material, configuration and dimension of workpieces to be finished.

Under these circumstances, the carrier device: 14 can be rotated in a horizontal plane by the driving belt wheel 10 driven from an electric motor (not shown) through a suitable transmission mechanism (not shown). It is now assumed that the belt wheels 10 and 12 are rotated in the direction of the arrows designated within the respective circles 10 and 12 to drive the carrier device 14 in the counterclockwise direction as viewed in FIG. 1 or clockwise direction.

In operation the carrier device 14 effects horizontal movement so that any cross section thereof travels rectilinearly in the direction of the arrow 24 (see FIG. 1) between the centers of both wheels 10 and 12 while it is guided by the rollers 16, 18 and 20 and subsequently semicircularly in the direction of the arrow 24' around the wheel 10 by virtue of the latter and rollers 18 and 20 followed by rectilinear movement in the direction of the arrow 24" between the centers of both wheels and the subsequent semicircular movement in the direction of the arrow 24 around the driving wheel 12. Therefore it will be appreciated that with the carrier device 14 moved, any point on or in the layer of abrasives 22 loaded in the device eifects horizontal movement including a pair of rectilinear movement portions between the centers of both wheels and 12 and a pair of semicircular movement portions around the respective wheels with each of the rectilinear portions merged at each end into the adjacent semicircular portion. In other words, movement of the carrier device 14 causes a stream of abrasive effecting movement of the character just described.

The length of the rectilinear movement of the layer of abrasives 22 and accordingly a distance between the centers of the two belt wheels 10 and 12 designated by the reference character L or L may be selected to have any magnitude dependent upon the size of workpieces to be finished and the capability of the apparatus to treat the workpieces per each day. It has been found that the distance L or L may be varied from a magnitude as low as less than 1 meter to a magnitude exceeding 10 meters. Also the layer of abrasives 22 may have any desired width and any desired thickness in accordance with the particular application.

With the carrier device 14 moved in the counterclockwise direction as viewed in FIG. 1 to establish the stream of abrasives as above. described, any suitable holding and driving means can be utilized to introduce a workpiece 26 for example from its position 26 illustrated in FIG. 1 into the carrier device 14 adjacent the righthand and lower end portion thereof as shown at the arrow 28 whereupon the workpiece may be pushed against the surface of the lower rectilinear stream portion of the abrasives adjacent the end of the rectilinear movement portion. Alternatively the workpiece may be put in the stream. The holding and driving means are symbolically designated by a small circle within the rectangle of the workpiece in FIG. 1. Then the holding and driving means are operated to move the workpiece 26 in counterfiow relationship on the surface or in the interior of the stream. One position of the workpiece being finished is illustrated at its position 26 in FIGS. 1, 2 and 3.

When the workpiece 26 has reached substantially the beginning or the lefthand end of the lower rectilinear stream portion or when it has substantially traveled the distance L, it can be raised from the stream of abrasives and then brought into its position 26" shown in FIG. 1 as the finished product.

Alternatively if the workpieces 26 is required to be further finished then the raised workpiece 26" may be moved along its semicircular path 28' around the wheel 10 by the same holding and driving means without it contacting the semicircular stream portion of the abrasives. Thereafter, when the. workpieces reaches above the end of the upper rectilinear stream portion it will be pushed against or put into that stream portion while it ismoved in the direction of the arrow 28 or in counterflow relationship to be further finished through the use of the same holding and driving means. At the beginning or the righthand end of said movement portion the finished workpieces will be similarly raised from the stream and then brought into its position 26 illustrated in FIG. 1 as shown at the arrow 28". Thus the workpieces 26 has been completely surface finished.

In either case it is to be understood that a series of workpieces can be successively introduced into the carrier device 14 at any suitable intervals of time to be finished with the rectilinear stream portion or portions of abrasives in the manner as above described.

Thus it will be appreciated that the present apparatus can surface finish workpieces on the basis of production line. If a single production line is desired, the workpieces 26 will be successively fed from their position 26 to their position 26" in the manner as above described. Alternatively if workpieces is surface finished on the basis of double production line, the rectilinear portion designated at the arrow 24 of the carrier device 14 may be used to surface finish the workpieces 26 on the line 28 while at the same time the portion thereof designated at the arrow 24" may be used to surface finish workpieces 27 on the separate line 28".

From the foregoing it will be apparent that the invention comprises the use of the rectilinear stream portion of the abrasives along for purpose of surface finishing. Therefore the method and apparatus of the invention may be called the bee-line flow finishing type.

In practicing the invention the relative speed between the workpiece and the rectilinear stream portion of the ab.asives is of the most importance. In order to perform consistently uniform surface finishing with a high efficiency and low costs, one must consider an extent to which the pressure of the loose abrasives in its flowing layer can be applied to the particular workpiece. It has been found that, for satisfactory results, the layer of abrasives should have a speed ranging from 70 to 300 meters per minute. A speed between and meters per minute is generally effective for surface finishing workpieces made of iron, steel, stainless steels, non-ferrous metals etc. For extremely stout or tenacious materials or for the purpose of heavy grinding, it has been especially found that the speed of the layer of abrasives may range from 300 to 500 meters per minute without any damage to workpieces.

It should be understood that the workpieces are required to be put in finishing engagement with the rectilinear stream portion of the abrasives for a period of time sufiicient to be thoroughly surface finished with the abrasives in that stream portion. Therefore the workpieces must relatively travel the length L or L or L L of the rectilinear stream portion, as the case may be, for such a period of time. It has been found that that period of time is preferably in the order of from 10 seconds to 15 minutes for the speed of the abrasive stream as previously specified. Also it has been found that the relative speed between the workpieces and the rectilinear stream portion of the abrasives preferably ranges from 70 to 500 meters per minute.

Referring now to FIGS. 4 to 8 inclusive there is illustrated a modification of the invention wherein a stream of abrasives such as previously described is established in a vertical plane. An arrangement illustrated may be called the horizontal recirculation type and is especially suitable for use on a table.

The arrangement comprises a pair of spaced belt wheels 40 and 42 disposed in a common horizontal plane and a carrier device of channelled endless belt type generally designated by the reference numeral 44 and spanned in tensioned state between both belt wheels. The carrier device 44 is formed of any suitable flexible, tough material such as a flax filled urethane rubber or the like and has a quantity of abrasives 52 such as the abrasives 22 as previously described.

When a drive (not shown) rotates one of the belt wheels for example the wheel 40 in the direction of the arrow designated within a circle 40 or in the counterclockwise direction as viewed in FIG. 4, any cross section of the device 44 travels along a closed loop comprising a rectilinear portion, semicircular portion, another rectilinear portion and another semicircular portion consecutive to each other as shown at the arrows 54, 54, 54 and 54 respectively as in the arrangement illustrated in FIGS. 1 to 3 inclusive. In this case, however, it is noted that the closed loop lies in a vertical plane. Therefore it is essential that any portion of the abrasives 52 within the carrier device 44 should be prevented from falling down from that portionof the device as traveling along the semicircular portion 54' or 54 or the lower rectilinear portion 54".

To this end, the carrier device 44 made of a flexible,

tough material as above described has a pair of opposed side walls 46 longitudinally undulating with valleys 48 of the undulation disposed at substantially equal intervals and inwardly foldable. Disposed along the major part of the upper rectilinear section 54 of the closed loop are a plurality of sets of a bearing roller 60 and side guide rollers 62 and 64 (see FIG. 6) at substantially equal intervals to define the U-shaped cross section of the carrier device as traveling along the upper rectilinear section 54. These rollers 60, 62 and 64 may be identical to the rollers 16, 18 and 20 as previously described in conjunction with FIG. 3 except for the concave contour of the roller 60. The rollers 60 of concave contour are effective for centering the carrier device 44. If desired, bearing rollers such as the bearing rollers 16 may be used.

Both a transitional region from the upper rectilinear section 54 to the adjacent semicircular portion 54' or 54" of the closed loop and each adjacent portion of the semicircular portion are provided with a plurality of sets of four rollers 60', 62, 64' and 66 as shown in FIG. 7 disposed at substantially equal intervals. The bearing roller 60 is identical to the bearing roller 60 and two opposed side guide rollers 62' and 64 are shorter than the side guide rollers 62 and 64 and inclined toward each other with the rider roller 66 of concave contour disposed above the side rollers. As the side guide rollers 62 and 64' are near to the belt wheel 40 or 42 they are more inclined toward each other and correspondingly the rider rollers 66 may be progressively shorter. The roller sets 62'66 are in rolling engagement with the adjacent portions of the carrier device 44 whereby they cooperate with each other to render the upper opening of the U progressively narrower in one of the transitional ranges until the opening is completely closed with both legs of the U somewhat overlap each other as shown in FIG. 8. In the other transitional range they serve progressively to open the upper opening of the U until it is completely opened at the entrance of the rectilinear device section.

In order to maintain the closed sectional profile of the carrier device 44 on the remaining portion of the closed loop or in the course of the return path, a plurality of sets of four rollers 60", 62", 64" and 66" as shown in FIG. 8 are disposed at substantially equal intervals and in rolling engagement with the adjacent portions of the device except for the semicircular portion thereof. The roller set 6066" are substantially similar to that shown in FIG.'7 excepting that the side guide rollers 62 and 64 are substantially parallel to each other and that the rollers 60 and 66 are the lower and upper rollers acting as a pressing and a bearing roller respectively.

For the semicircular portion 54' or 54" the roller sets are identical to the roller set 60"-64" except for the side rollers 64" being omitted and instead replaced by the belt wheel 40 and 42.

With the arrangement of the roller sets as above described it will be appreciated that any cross section of the carrier device 44 is maintained U-shaped on the major part of the upper rectilinear portion 54, and as it approaches the belt wheel 42 its upper opening becomes progressively narrower until the opening is completely closed. Thereafter the cross section of the carrier device 44 travels along the return path 54-54"-54'" while it maintained closed and as it moves away from the belt wheel 40 it is progressively open until it assume the U- shape at the beginning of the upper rectilinear portion 54.

When the belt wheel 40 is rotated in the counterclock wise direction as viewed in FIG. 4 any cross section of the carrier device 44 travels in the direction of the arrow 54, 54, 54" and 54" in the manner as above described. Therefore, within the carrier device 44 as traveling along the upper rectilinear portion 54 of the close loop, a rectilinear stream of the abrasive having the effective length of L is formed in that portion 54. This stream is utilized to surface finish workpieces in the same manner as previously described in conjunction with FIGS. 1 to 3 inclusive. Thus workpieces 56 successively pass from their start position 56 to a working line 68 along which they are surface finished and then delivered to their finished position 56.

As an example, an apparatus such as illustrated in FIGS. 4 to 8 was used to surface finish pin-shaped workpieces. and screws. While the pointed ends of the pinshaped workpieces or the heads of the screws were maintained projecting from the surface of the rectilinear stream portion of the loose abrasives they were successively passed through that stream portion at a relative speed as above specified for a period of time as above specified. During movement they were tilted at any desired angle to the direction of the stream and/ or they were rotating about their axes. In this way their particular portions could be successfully surface finished.

Referring now to FIGS. 9 to 13 inclusive, there is illustrated another modification of the invention especially suitable for surface finishing long large-sized workpieces. Two pairs of chain wheels 110, a, 112 and 112:: having the horizontal shafts (not shown) are suitably supported on a machine frame (not shown) such that a line passing through the centers of the wheels 110 and 112 of one wheel pair crosses a line passing through the centers of the Wheels 110a and 112a of the other pair to form an X-shaped arrangement. A pair of carrier devices 114 and 114a of channelled endless belt type as will be hereinafter described are tightly spanned between the wheels 110 and 112 and between the wheels 110a and 112a respectively with endless chains and endless belts interposed therebetween. Thus both carrier devices are juxtaposed in an X-shaped arrangement. Only the chains and belt for device 114 are shown by the reference numerals 116 and 118 respectively. The lower wheels 110 and 110a are adapted to be driven in the opposite directions by a common electric motor through a suitable transmission mechanism to rotate both carrier devices 114 and 114a in the corresponding directions and in the respective vertical planes although the motor and transmission mechanism are not shown for purpose of simplification. If desired, the upper wheels 112 and 112a may be similarly driven by the same motor. With the arrangement illustrated, any cross section of each device 114 or 114a travels along a rectilinear path between the associated pair of wheels as in the previous arrangement.

The carrier devices 114 and 114a are of the same construction and therefore one of the devices will now be described. As best shown in FIGS. 11 and 12, the carrier device 114 has a bottom composed of the endless belt 118 rigidly secured to the endless chain pair 16 engaging the chain wheels 110 and 112 and both side walls each composed of a plurality of outwardly flared plates 120 alternating the similar plate 121 with the plates 120 and 121 being attached to the chain 116 or the belt 118 as shown in FIG. 12. These plates 120 and 121 overlap each other when the associated portion of the carrier device 114 is moving along the rectilinear path. When the plates are passing around each chain wheel they will decrease in the overlapped area but still form the continuous side wall free from any gap therebetween. Therefore a quantity of abrasives loaded in the carrier device 114 as will be described later is prevented from falling down from the side wall of the device during its movement.

As best shown in FIG. 10, a transfer chute 122 or 122a extends from adjacent the upper chain wheel 110 or 110a for one of the carrier devices 114 or 114a to that portion of the other carrier device positioned directly below the top of the one carrier device to permit the abrasives to transfer from one to the other of the carrier devices.

In order to initially load a quantity of abrasives into each of the carrier devices 114 or 114a, both devices may be first driven in the manner as previously described.

Then a quantity of abrasives is fed into each of the moving carrier devices 114 or 114a from the lower end of its upper rectilinear section formed between the associated upper and lower wheels or the associated chute 122 or 122a to form a layer 124 or 124a of abrasives loosely and uniformly distributed to a predetermined depth in the upper rectilinear carrier section throughout the length whereupon feeding of the abrasive terminates. It is to be noted that each of the carrier devices should be inclined at such an angle that the layer of abrasives 124 or 124a does not collapse within the ascending rectilinear carrier section. As soon as any portion of the abrasive layer 124 has reached the upper end of the ascending rectilinear carrier 114 section it falls down onto the other rectilinear section through the associated chute 122. Then the falling portion of the abrasives in the form of a layer ascends in the rectilinear section as the latter moves upwardly. When any portion of the abrasive layer 124a has reached the top of the latter section, it falls down onto the original rectilinear carrier section through the chute 122a to repeat the process just described. Thus it is apparent that the layers of abrasives 124 and 124a travel along a closed loop including a pair of rectilinear portion inclined and crossing each other. Namely there have been established a pair of rectilinear stream of the abrasives crossing each other into an X-shaped arrangement.

Under these circumstances, holding and driving means of any known construction can be used to surface finish workpieces one after another with either or both of the two rectilinear abrasive streams in the similar manner as previously described in conjunction with FIGS. 1 to 3 inclusive. For example, one of workpieces 126 is fed in the direction of the arrow 128 from adjacent the upper end of the rectilinear carrier section into the carrier device 114 through the use of holding and driving means schematically designated at a rod connected to the workpiece 126. In the carrier device 114 it descends along the rectilinear carrier section in counterfiow relationship while being surface finished with the abrasives in the rectilinear abrasive stream. Near its position just below the upper Wheel 112 the workpiece is moved from the carrier device 114 to its position 126" as shOWn in the dot-and-dash arrow 128. Thereafter the workpiece is moved in the other carrier device 114a as shown at the dot-and-dash arrow 128" and 128' (see FIG. with its orientation remaining unchanged. Then the workpiece such as 126 is subject to surface finishing in the carrier device 114a in the same manner as in the device 114 after which the workpiece is passed from the device 114a to its position 126". In this way the workpiece has been completely surface finished. The process just described is repeated with the succeeding workpieces.

Altemately the surface finishing operation may be started with the carrier device 114a with the workpieces transferred from the device 114a to the devices 114 at the lefthand side thereof as shown at the dot-and-dash arrow 128" (see FIG. 10).

In FIGS. 9 and 10 the stream of abrasives are designated at the arrows 120, 120, 120 and 130, 130, 130" etc. and the workpieces being surface finished are illustrated at various positions 126', 126" etc.

From the foregoing it will be appreciated that according to the surface finishing operation as above described, the workpieces are surface finished in the opposite directions resulting in no occurrence of partial polishing and polishing shadows due to the conventional undirectionally surface finishing methods and hence in uniform and homo geneous finishing. This is particularly effective for surface finishing long workpieces such as mufflers for use in autobicycles, bumpers, radiator grilles and decorative straps for use in automobiles and the like. It will be also understood that the workpieces within one of carrier devices 114 or 114a are automatically maintained at an angle of inclination corresponding to that of the latter and that the workpieces transferred from the device 114 to the device 114a and vice versa have an angle of inclination automatically varied so as to correspond that of the device 114a or 114 by the action of resistance to the workpieces of the rectilinear abrasive stream.

Alternatively both carrier devices 114 and 114a may be put in separate working lines beginning at the position 126 and 126 and terminating at the position 126" and 126".

If desired, the chutes 122 and 122a each may be operatively coupled with a motor-operated vibrator (not shown) to aid in transferring the abrasives from one to the other of the carrier devices. Alternatively, a rotary disk or rollers (not shown) may be disposed on the bottom of each chute.

Dependent upon their configuration, the workpieces may effect, in addition to rectilinear movement in the rectilinear abrasive stream, rotational movement about their axes and/or serpentine movement in the vertical and/ or horizontal directions or direction.

Conveniently cover means (not shown) may be pro vided for covering each of the carrier devices 114 or 114a to prevent the abrasives from scattering from the associated device.

With the wet type of abrasives used a liquid such as water containing a suitable compound or compounds may be poured into the layer of abrasives 124 or 124a at the upper end of the associated rectilinear carrier section and exhausted from the lower end of each chute (not shown).

If desired, the endless chain pair may be omitted and instead of the endless belt may directly engage belt wheels used in place of the chain wheels as shown in FIG. 13 wherein like reference numerals designate the components similar or corresponding to those illustrated in FIG. 12.

The figure of the speed and dimension of the rectilinear abrasive stream, the speed of the workpiece relative to the latter and the finishing time referred to the arrangement shown in FIGS. 1 to 3 inclusive are equally applicable to the arrangement illustrated in FIGS. 4 to 8 or FIGS. 9 to 13 inclusive.

Unlike the conventional type of gyration finishing methods in which a cylindrical barrel having loosely loaded therein a quantity of abrasives is rotated to form a flowing layer of the abrasives in the form of a disk, a cone, or a cylinder, and wherein workpieces are forced on or put into the flowing layer to be finished, the invention is characterized in that a rectilinear stream of abrasives is used resulting in the possibility of easily subjecting workpieces to uniform surface finishing free from partial polishing and/ or polishing shadows due to the conventional finishing methods.

While the invention has been illustrated and described in conjunction to the several preferred embodiment thereof, it is to be understood that various changes and modifications may be resorted to without departing from the spirit and scope of the invention. For example, the arrangement shown in FIGS. 1 to 3 and FIGS. 4 to 8 inclusive may be rotated in the clockwise direction rather than counterclockwise direction with the workpieces moved in a direction reversed from that described.

What I claim is:

1. In an apparatus for surface finishing workpieces, the combination of movable carrier means of channelled endless belt type of a flexible durable material, a pair of driving belt wheel and a tuning belt wheel for spanning said carrier means in tensioned state to form a pair of parallel rectilinear sections therebetween, a quantity of abrasives loosely and uniformly distributed in the form of a layer within said carrier means, means for maintaining a substantially U-shaped cross section of at least one of said rectilinear sections of said carrier means, and means for holding and driving the workpieces one after another to move, at a predetermined relative speed, the workpieces in counterfiow relationship with respect to a rectilinear stream portion of said abrasive layer in said U-shaped rectilinear section of said carrier means driven by said driving belt wheel While maintaining the workpieces in surface finishing engagement with said rectilinear stream (bee-line flow) portion.

2. An apparatus for surface finishing workpieces as claimed in claim 1, wherein said carrier means are rotatably disposed in horizontal plane and wherein said carrier means are maintained in a substantially U-shape of cross section and guided by both a plurality of bearing rollers disposed on the bottom and a plurality of side guide rollers disposed on each side wall with at least one of the U-shaped rectilinear sections of the carrier device utilized for surface finishing the workpieces.

3. An apparatus for surface finishing workpieces as claimed in claim 1 wherein said carrier means have a pair of opposed side walls longitudinally undulating with valleys of the undulation disposed at substantially equal intervals and inwardly foldable and are rotatably disposed in a vertical plane and wherein said carrier means have an upper rectilinear section maintained in a substantially U-shape of cross section and guided by both a plurality of bearing rollers disposed on the bottom of the section and a plurality of side guide rollers disposed on each side wall while having the remaining section maintained and guided in its closed state by a plurality of rollers disposed on each of the four sides of the sections.

4. In an apparatus for surface finishing workpieces comprising the combination of a pair of carrier means of U-shaped endless belt type juxtaposed in tensioned state in the vertical planes by having two pairs of belt wheels engaging the same respectively, both said carrier means being rotatable in the opposite directions with the upper rectilinear sections thereof ascending, a layer of abrasives loosely and uniformly disposed in each of said upper rectilinear carrier sections, chute means extending from adjacent the upper end of each of said rectilinear carrier section to that portion of the other rectilinear carrier section positioned below said upper end of said each rectilinear carrier section, and means for holding and driving the workpieces one after another to move, at a predetermined relative speed, the latter in counterflow relationship in said ascending layer of abrasives while maintaining the workpieces in surface-finishing engagement with said layer of abrasives. v

5. An apparatus for surface finishing workpieces'as claimed in claim 4, wherein each of said carrier means has both side walls each composed of a plurality of outwardly flared plates alternating the similar plates.

6. An apparatus for surface finishing workpieces as claimed in claim 4, wherein saidpredetermined relative speed ran es from to 500 meters per minute.

References Cited UNITED STATES PATENTS JAMES L. JONES, 111., Primary Examiner

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