US2164067A - Machine for dressing external cylindrical surfaces - Google Patents

Description

NVENTOQS finson f v MTTO@| Eye 5 Sheets-Sheet 1 A. M. JOHNSON ET AL Filed Feb. 23, 1958 MACHINE FOR DRESSING EXTERNAL CYLINDRICAL SURFACES June 27, 1939.

June'27, 1939. A. M. JOHNSON ET AL 2,164,067

MACHINE FOR DRESSING EXTERNAL CYLINDRICA SURFACES Filed Feb. 25, 1938 5 Sheets-Sheet 2 June 27, 1939. A. M. JOHNSON ET AL 2,164,067

MACHINE FOR DRESSING EXTERNAL CYLINDRICAL SURFACES Filed Feb. 23, 1958 5 Sheets-Sheet 3 iNVENTOQS June 27, 1939. A. M. JoHNsoN ET AL 2,164,067

MACHINE FOR DRESSING EXTERNAL CYLINDRICAL SURFACES Fil ed Feb. 23, 1938 5 h t 4 Patented June 27, 1939 UNITED STATES PATENT OFFICE MACHINE FOR DRESSING EXTERNAL CYLINDRIC'AL SURFACES Application February 23, 1938, Serial No. 191,912

18 Claims.

The invention relates to machines for dressing cylindrical surfaces, and more particularly to a machine for producing a true contour and smooth finish on the external surfaces of shafts and other elongated cylindrical bodies.

I-Ieretofore, the finishing of such cylindrical bodies has been accomplished generally by a grinding operation. This operation is ordinarily performed with an abrasive wheel revolving on a fixed axis eccentric of the work, the wheel having merely tangential contact with the surface of the work piece and therefore in operative engagement with a relatively small area thereof. The operation results in appreciable roughness and irregularity in the finished surface as well as in objectionable variations in the diameter and concentricity of the work at different points along its length. The latter defect is particularly noticeable in the case of substantially elongated bodies such as shafts, tubes, pistons, etc.

The present invention aims to overcome the defects inherent in the finishing operations heretofore employed and to this end is embodied in a machine for accurately and smoothly dressing the external surfaces of elongated cylindrical bodies by a honing or lapping operation in which the surface to be dressed is acted on by abrasive stones having a constant contact therewith over a substantial area. The abrasive stones are conveniently arranged in a'circular series in an annular frame encircling the work piece and are urged radially of the frame into constant engagement with the surface of the work piece. Relative reciprocation between the tool and the Work, together with either constant or intermittent rotation of one relative to the other, is utilized to rub the abrasive stones over the entire surface of the work piece to hone or lap the sur face to the desired finished condition.

With the foregoing in view, one object of the invention is to provide a machine adapted to effect relative rotational and reciprocato-ry motion between an elongated cylindrical work piece and a tool of the character above described, ina manner such that the tool is caused to act uniformly over the entire surface area to be dressed and to quickly true and smooth the surface.

, Another object is to provide an improved machine for dressing external cylindrical surfaces which may be adjusted to handle work pieces of widely varying length.

Another object is to provide an improved reciprocatory carriage for machines of the above general character which is of relatively light limit the invention to the specific form disclosed weight and yet extremely rigid and which may be manufactured economically.-

Still another object is to provide improved means for operatively connecting a rotatable member on a reciprocatory carriage with a sta- 5 tionarily supported power-actuated driving means.

A further object is to provide improved control devices for machines of the above general character.

Other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiment illustrated in the accompanying drawings, in which Figure 1 is a plan view of a machine embodying the features of the invention.

Fig. 2 is a side elevation of the machine.

Fig. 3 is a side elevation of the reciprocatory carriage with the headstock and other appurtenances removed.

Fig. 4 is a plan view of the carriage shown in Fig. 3.

Fig. 5 is a transverse sectional view of the carriage taken along the line 55 of Fig. 4.

Fig. 6 is a transverse sectional view of the carriage taken along the line 66 of Fig. 4.

Fig. '7 is a view partly in section of the means provided for supporting the drive shaft on the carriage.

Fig. 8 is a fragmentary side view of the carriage showing the driving head or headstock in elevation with a portion broken away to show the arrangement of the driving gear train.

Fig. 9 is an end elevation of the carriage and headstock.

Fig. 10 is a side elevation of the intermediate support for the limit switch supporting rod, as viewed from one end of the machine.

Fig. 11 is a side elevation of the support shown in Fig. 10.

Fig. 12 is a fragmentary end view of the tool and tool supporting fixture.

Fig. 13 is a sectional view taken along the line Iii-l3 of Fig. 2 showing details of the short stroking mechanism.

Fig. 14 is a detail View of the short stroking mechanism taken along the line 14-! of Fig. 13.

Fig. 15 is a schematic diagram of the electrical and hydraulic circuits of the machine.

While the invention is susceptible of various modifications and alternative constructions, we have shown in the drawings and will herein describe in detail a preferred embodiment, but it is to be understood that we do not thereby intend to but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Referring to Figs. 1 and 2 of the drawings, the machine selected to illustrate the invention comprises generally an elongated horizontally disposed base !6 having on its upper face a track or guideway comprising spaced parallel guide bars I! (Fig. 9). A head or carriage i8 is supported on the guideway for movement longitudinally of the base M3 by adjustable spool-shaped roller bearings l9 (Figs. 6 and 9) mounted on opposite sides of the carriage for engagement with the guide bars H. The carriage l8, as herein shown, is equipped with a headstock 2B and a tailstock 2! having centers 22 and 23, respectively, between which a work piece 24 may be supported in operative relation with a relatively stationary external honing tool 25.

While the tool 25 may be of any suitable construction, one of the most suitable for dressing external cylindrical surfaces comprises a cylindrical body 26 within which a plurality of abrasive stones 2! (Fig. 12) are arranged in a circular series. The stones are mounted for movement radially of the body 25 and suitable adjusting means actuated by knurled nuts 28 are provided for moving them radially inwardly to engage the surface of the work piece which extends concentrically through the tool.

In the particular machine disclosed, the tool 25 is supported on a stationary fixture 28 adjustably mounted on the base I6 of the machine. The adjustable mounting of the support permits shifting the tool toward or from the head end of the machine so that it may be positioned at any point required for proper operation on work pieces of different lengths.

The fixture 28 may be of any suitable construction and, as herein shown, comprises a transverse member 29 extending across the base l6 above the carriage l8. Projecting upwardly and forwardly from the member 29 is an arm 30 which, with the member, provides spaced supports for the tool 25. The arm 30 is formed with a slot opening toward the front of the machine while member 29 has a similar slot opening toward the end of the machine, the slots being formed to receive lugs 3| and 32 formed on a plate 33 rigid with the body 26 of the tool. The slot in arm 33 may be left open as the rotation of the Work tends to rock the tool in a clockwise direction as viewed in Fig. 12, and thus prevents disengagement of the lug. The slot in the member 25!, however, is provided with a latch or keeper 34 which holds the lug in place and serves to prevent endwise movement of the tool incident to the reciprocation of the work piece. The slots are preferably of sufiiciently greater size than the lugs to permit limited lateral movement or floating, of the tool to enable the tool to properly center itself on the work piece. Axial and rotational movement of the tool is effectively prevented by the supporting fixture.

Means is provided for reciprocating the carriage l8 and for rotating or indexing the work piece 24 to efiect the desired relative movement be tween the tool and the work piece. As shown in Figs. 1 and 2, the means for reciprocating the carriage comprises a cable drum 35 supported at one end of the machine and arranged to be driven in either direction by a rotary fluid motor 36 which receives pressure fluid from a suitable pump 31 driven by an electric motor 38. The cable drum is operatively connected with the carriage by means of flexible cables 39 and 40 which are secured to the drum so that one cable is Wound up and the other paid out incident to the rotation of the drum. The cable 40 passes over a sheave 4| at the end of the machine opposite the drum so that the force which it exerts on the carriage is opposite in direction to the force exerted by the cable 39. Thus, the carriage is moved to the left or toward the foot of the machine upon rotation of the cable drum in a counterclockwise direction as viewed in Fig. 2. Rotation of the drum in the opposite direction returns the carriage toward the head of the machine. With this arrangement, the carriage is reciprooated with a minimum of shock incident to the changes in direction of movement.

The direction of rotation of the cable drum 35 and, hence, the direction of movement of the carriage I8 is controlled by a reversing valve 42 interposed in the hydraulic circuit of the fluid pressure motor 36 as shown in Fig. 15. The reversing valve has a shiftable valve plunger 43 operative in one position to direct pressure fluid to the motor to effect rotation of the drum in a clockwise direction and effective in the other position to reverse the rotation of the drum. Pressure fluid supplied by a high pressure pump 44 driven by the pump motor 38 is utilized for shifting the valve plunger under control of a solenoidactuated pilot valve 45 the operation of which will be described in more detail hereinafter.

Means is provided for delaying operation of the reversing valve 42 for the purpose of introducing a dwell in the reciprocation of the carriage to increase the period of engagement between the tool and an area of the work piece adjacent a shoulder or other obstruction. To this end, the hydraulic circuit for the valve is provided with an adjustable delayed action valve 46 arranged to control the rate of fluid discharge. In the particular embodiment disclosed, only one delayed action valve is employed, thus providing a dwell at one end of the reciprocatory stroke. It will be appreciated, however, that a second valve may be incorporated in the reversing valve circuit when it is-desired to provide a dwell at both ends of the reciprocating stroke.

When operating on a shouldered work piece, accurate control of carriage movement is essential to enable the tool to work up to the shoulder and yet avoid contact between the same which might damage the tool. To obtain such control, the machine is provided with an adjustable stop in the form of a cross bar 46 slidably supported on the base I6 for movement toward and from the rear end of the carriage 18 as shown in Figs. 1 and 2. The face of the cross bar carries pads or bumpers 41 of rubber or other suitable resilient material spaced longitudinally of the bar for engagement by stop-engaging members 48 on the end of the carriage. The members 48 may be screw threaded in suitable supporting blocks 48 welded or otherwise secured to the carriage so that they may be adjusted independently to insure simultaneous engagement with the bumpers 4?. Clamping screws 49 serve to hold the cross bar in set position on the base so that the carriage is stopped by engagement of the members 48 with the bumpers 41 before the shoulder of the work piece hits the tool.

The means for rotating and indexing the work comprises suitable power-driven means mounted on the base 16 and operatively connected with the headstock 20 by means of a splined drive shaft 50. The power-driven means may be generally similar to that disclosed in the patent to Albert M. Johnson, No. 2,106,217, granted January 25, 1938, and includes generally an electric motor 5| for rotating the shaft 50 continuously and a hydraulic cylinder 52 and piston 53 for indexing the shaft. As will be seen by reference to Fig. 15, the cylinder 52 is connected in the hydraulic circuit of the carriage reciprocating motor 36 so that the piston is shifted to opposite ends of the cylinder alternately each time the motor is reversed. The piston is formed with rack teeth meshing with a gear 54 arranged to drive the shaft 50 through a pawl and ratchet mechanism such as that disclosed in the aforementioned patent. Through the medium of a clutch (not shown) operable under control of a manual lever 55, either the motor 5| or the hydraulic mechanism above described may be connected selectively with the splined driveshaft 56 to rotate or index the shaft.

The drive shaft 56 is journaled on the base l6 at its driven end only, and means is provided on the carriage I 8 for supporting the opposite end of the shaft. This makes it unnecessary to extend the shaft for the entire length of the base as has heretofore been the practice, eliminates any possibility of the shaft binding when the carriage is adjusted on the guideway by taking up play between the rollers l9 and the guide bars I1, and additionally provides a substantially longer bearing surface which minimizes wear and eliminates vibration. To this'end, the shaft is arranged to telescope into a tubular member 56 supported at opposite ends on the underside of the carriage l8. As shown in Fig. '7, the end of the member 56 adjacent the foot of the machine is fitted with a plug 51 which has a stud 58 projecting beyond the end of the member. The stud is journaled in a roller bearing 59 supported by a bracket 66 depending from the carriage l8. The other end of the member 56 is anchored to a flange 6| formed integrally with a gear 62 supported in antifriction bearings 63 in a depending portion of the headstock, as shown in Fig. 8. The tubular member 56 preferably has an internal diameter such as to receive the shaft snugly, thereby permitting relative axial sliding movement of the parts and yet serving tosupport the shaft in a manner such that vibration is substantially eliminated. The gear 62, above referred to, has a slidable nonrotatable relation with the 7 drive shaft 50 so that the gear and tubular member 56 rotate with the shaft and wear on the interior of the member is reduced to a minimum.

Gear 62 is utilized to drive a hollow spindle 64 journalled on the headstock 20, which spindle is adapted to receive the center 22. In the present instance, the drive for the spindle is taken through an intermediate gear 65 meshing with a gear 66 rigid with the spindle. Rotational movement of the spindle may be imparted to the Work by a suitable dog 61, as shown in Fig. 1. It will be apparent that with the construction above described the work piece 24 may be rotated or indexed and simultaneously reciprocated relative to the tool 25. Accordingly, the tool is enabled to act uniformly on the entire surface area of the work piece and to dress it to a true contour and smooth finish.

Means is provided for supplying an ample flow of clean coolant fluid to the work during the honing process to remove loose particles of metal or abrasive and to prevent undue heating of the.

tool or work. The coolant supply means includes a suitable pump 68 (Fig. 15) driven by an electric motor 69. As shown in Fig. 1, the pump and motor are mounted at one side of the base I6 adjacent the rear end of the machine. The pump is arranged to draw the coolant from a reservoir 70 preferably located within the base l6 and to deliver the coolant under pressure to a suitable filter ll. After passing through the filter, the coolant is carried to the work by a pipe 12 which terminates in branches l3 and 14 positioned to direct the coolant over the work at opposite ends of the tool 25.

In order to reduce the weight of the reciprocating parts to a minimum, the invention contemplates the use of a carriage of novel and improved construction which is light in weight and yet extremely rigid. Referring to Figs. 3 to 6, the carriage in its preferred form is fabricated from sheet or plate stock with the various elements welded together to form a unitary structure.

As herein shown, the carriage I 8 comprises generally an upper rectangular box-like frame having side walls 15, end walls 16 and a bottom plate ll. The bottom plate is. slotted longitudinally as at 18 throughout a substantial portion of its length, and below this slot is mounted a trough-like lower frame having side walls 19, end walls 80, and a bottom plate 6|.

Within the lower frame are fitted a plurality of longitudinally spaced transverse stiffening members 82 in the form of inverted, generally U- shaped plates. These are welded to the side walls and the bottom plate of the frame, thus forming a series of compartments or pockets in which coolant draining from the work piece may be collected. Each of the pockets is provided with an outlet 63 in one of the side walls for draining the coolant into a trough for return to the coolant reservoir '56. As shown in Figs. 5 and 6, the bottom wall SI of the lower frame is inclined slightly in the direction of the opening 83 to facilitate the discharge of the coolant.

The stiffening members serve to render the lower frame of the carriage very rigid and additional rigidity is obtained by the provision of triangular gusset plates 84 extending between the side walls 79 of the lower frame and the underside of the bottom plate ll of the upper frame. These plates, together with the stiffening members 82, give the carriage transverse rigidity, while the vertical side Walls of the upper and lower frames render the carriage rigid longitudinally.

Welded to the side and bottom walls of the upper frame at spaced points along the lateral edges of the carriage is a series of blocks 85 having vertically disposed bores adapted to receive supporting studs 86 which carry the spool-shaped bearing members l9 for supporting the carriage on the guide bars ll. In the particular embodiment shown, eight of the roller bearings are employed, four on each side of the carriage, although it will be appreciated that this number may vary with carriages of different lengths.

Formed integrally with the upper and lower frames at the forward end of the carriage is an extension 86 constituting a base to which the headstock 26 may be bolted. A bed plate 8? extending longitudinally of the upper frame and secured to the bottom plate 11 as by bolts 88 provides a support for the tailstock 2|. In order to adapt the machine for handling work pieces of diiferent lengths, adjustment of the distance between the centers 22 and 23 is essential. Accordingly, the tailstock is adjustably mounted on the bed plate 81 by means of a suitable clamp engaging a T-slot 89 extending longitudinally of the bed plate. With this arrangement, the machine may be readily adapted to hold a work piece of any length within the capacity of the machine.

Suitable control means is provided for controlling the power-driven means for rotating the work and reciprocating the carriage. This means includes manually operable devices for starting and stopping the various motors together with limit switches actuated by the carriage in its movement to control the direction of carriage movement. As shown in Figs. 1 and 2, two limit switches are provided, one switch 9! defining one end of the carriage stroke and another switch 92 defining the other end of the stroke. These switches may be of any suitable and well known construction. and include an operating member 93 adapted to be engaged by a dog 94 mounted on the carriage, as shown in Fig. 10. When the dog engages the operating member, the associated switch is closed to complete a circuit for one of the solenoids 95 and 98 which actuate the pilot valve 45 to control the supply of pressure fluid to the driving motor 36 for the cable drum 35.

In order to adjust the movements of the carriage to conform to the length of the work piece being dressed, means is provided for varying the relative spacing of the limit switches as required. To this end, the switches are mounted on a rod 91 extending longitudinally of the base it. The arrangement is such that either switch may be moved along the rod to any desired position and a set screw 98 firmly clamps the switch in set position.

The limit switch rod 97 is supported at opposite ends by brackets 98 mounted on the base i6. Suitable means is provided for supporting the rod intermediate its ends in a manner such that the adjustment of the limit switches is not interfered with. As shown in Figs. 10 and 11, the supporting means includes a post 99 slidably supported below the rod for movement toward and from the same in a bracket 509 carried on the side wall of the base 56. A pin iEiI projecting radially from the post through a vertically disposed slot I02 on the brackets H30 provides a handle by wh ch the post may be moved to its upper position to engage and support the rod 9?. The post is normally held in its upper position by a detent in the form of a flat bar I93 pivoted at one end on the bracket I09 and adapted to engage in a slot in the side'of the post. A spring H34 actng on the bar holds it in latching position. When it is desired to move one of the limit switches past the supporting post, the latch I03 is withdrawn, thereby permitting the post to drop into its lower position and out of the path of the limit switch.

It may be necessary at times to position a limit switch substantially at the point at which the support is located. In order to avoid any difficulty on this score, the bracket E is slidably supported on a dovetailed slideway I05 for movement longitudinally of the base. A clamping screw I06 serves to hold the bracket in set position on the slideway.

In some cases, it is desirable to subject specific areas of the work piece to additional action of the tool to remove high spots or irregularities. For this purpose. manually operable means is provided for controlling the reciprocatory movements of the carriage independently of the carriage-actuated limit switches above described. This operation is commonly known as short stroking.

The manual control or short stroking mechanism comprises a pair of switches I0! and I08 connected in parallel with the limit switches 9| and 92 in the circuits of the pilot valve solenoids and 96, as shown in Fig. 15. Referring to Fig. 14, the switches I01 and I08 are mounted in opposed relation in a casing I09 mounted in a conveniently accessible position on the front wall of the base I6. Operation of the switches is effected selectively through the medium of a hand lever I I0 fast on a rock shaft I I I journaled in the casing I09. Mounted on the rock shaft III within the casing is a collar IIZ having a radially projecting lug II3 engageable with one end of a switch operating member IE4 which is pivoted on the casing I09 at its other end.

The switch operating member H4 is disposed between the switches I01 and I08 and engageable therewith to close the switches alternately when rocked about its pivot by means of the hand lever IIO. Thus, when the hand lever is rocked in a clockwise direction as viewed in Fig. 14, the lug II 3 rocks the switch-actuating member in a counterclockwise direction to close the switch I0'I. On continued movement of the hand lever, the lug is moved out of the path of the switchactuating member and the member is returned to normal by the spring action of the switch. Closure of the switch I08 is efiected by rocking the hand lever in the opposite direction. The lug H3 and switch-actuating member H0 thus constitute a load and fire mechanism which permits the switches to be opened and closed in rapid succession. This action imparts a series of quick, short reciprocatory strokes to the carriage I0. It will be apparent that the short stroking may take place at any point along the path of the carriage travel so that any selected area on the work piece may be subject to additional action of the tool.

The electrical and hydraulic circuits of the machine as herein disclosed, are shown diagrammatically in Fig. 15 of the drawings. Referring to the drawing, it will be observed that the various driving motors, including the coolant pump motor 69, the spindle driving motor 5% and the pressure fluid pump motor 38, are all arranged to be started and stopped under control of push button switches conveniently accessible to the operator. The coolant motor 69, for example, is started in operation by momentary actuation of a push button switch H5 which complpetes a circuit from a conductor IIG of the power line, winding of a solenoid II l, starting switch II5 and a normally closed stop switch E I6 to the other conductor I 59 of the line. The solenoid II! on energizing operates a switch I29 to close the operating circuit for the motor 69. At the same time, the solenoid completes a holding circuit for itself by closing switch i2I. Operation of the push button switch IIB opens the holding circuit for the solenoid, which thereupon becomes deenergized and opens the circuit for the motor 69.

The spindle driving motor 5| is provided with starting switches I22 and I23 arranged to connect the motor with the line circuit for operation in either direction. Switch I22 is actuated by a solenoid I24 and switch I23 is operated by a solenoid I25 which are connected in circuit selectively by a manually operable reversing switch I26. A normally open push button starting switch I 21 and a normally closed push button stop switch I20 are connected in circuit so as to control either solenoid connected up by the reversing switch. With the reversing switch in the time.

position shown in the drawings, closure 'of the switch I21 completes an energizing circuit for the solenoid I24 extending from line conductor I 5, winding of solenoid I 24, reversing switch I26, starting switch I21 and stop switch I28 to line conductor II9. Solenoid I24 closes the motor switch I22 and completes a holding circuit foritself independently of the starting switch by way of its own holding switch I29 and a normally closed auxiliary switch I30 which shunts the starting switch. .With the reversing switch in its other position, solenoid I25 is energized upon the closure of starting switch I21 to close the motor switch I23 and complete a holding circuit for itself by way of switch HI and auxiliary Opening of the stop switch I 28 is switch I30. effective to deenergize either solenoid and stop the motor The circuit for the pump motor 38 includes a switch I32 arranged to be closed by a. solenoid I33 energized by momentary actuation of a push button starting switch I34; The solenoid by closing a switch I35 completes a holding circuit for itself by way of a normally closed auxiliary switch I36 and a normally closed push button stop switch I31. Momentary opening of the stop switch I31 is effective to stop the pump motor and thus discontinue the supply of pressure fluid to the hydraulic carriage reciprocating motor,

carriage. 7

Auxiliary switches I30 and I36 are operated by a solenoid I38 for automatically stoppingthe machine under control of a stroke counter or timer. The counter or timer may be of any suitable type and is provided with a normally open switch I39 closed either in response to the operation of the carriage through a predetermined number of reciprocations or after a predetermined intervalof circuit for the solenoid I38 which opens the auxiliary switches I30 and I36 and thus stops the spindle driving motor and hydraulic pump motor. f

When it is desired to stop the machine before the operation of the switch I39, this may be" done by operating a push button switch I40'which completes a circuit for the solenoid I38 independently of the switch I39. The switch I39'may be rendered inefiective temporarily to stop the machine when it is desired to increase the number of strokes or to increase the operating period by opening a normally closed switch I4| which is connected in series relation with the switch I39.

It will be observed that the circuit for the solenoid I38 is completed through limit switch 9| which is closed when the carriage is at the extreme right or head end of the machine. Thus, automatic stopping will invariably take place with the carriage in retracted position.

Limit switches 9| and 92 and the multiply connected short stroking switches I01 and I08 are arranged respectively to control circuits for the draulic motor 36 which accordingly moves the carriage toward the right.

Having in mind the foregoing detailed descrip+ The switch I39 completes an energizing" tion of the preferred embodiment of the invention, the operation of the machine will be read ily understood. In operating the machine, the first step of course is to set up the work between the centers 22 and 23. This is most conveniently done by first inserting the work piece through the tool and then adjusting the tailstock so that the centers engage the ends of the work piece in the usual manner. The tool is then secured to the tool supporting fixture by engagingthe lugs 32 in the slots provided for this purpose in the fixture.

The carriage stroke is adjusted by setting the limit stops 9| and 92 on the control rod. These switches are positioned so that the dog 94 engages the respective switches as the ends of the work piece approach the tool. The stroke counter or timer may also be set to close the switch I39 when the work piece has received the required number of tool operations.

If the work is to be honed, the clutch-actuating lever 55 is set to connect the spindle driving motor 5| with the splined drive shaft 50. The driving motor 5|, pressure fluid pump motor 38 and coolant pump motor 69 are started by operation of the appropriate push button switches.

The honing operation then proceeds without further attention until uninterrupted by the closure of the counter or timer switch I39 which stops the drive motor 5| and pump motor 38 upon the carriage reaching the end of its return stroke.

For the lapping operation, the clutch control lever 55 is shifted to operatively connect the hydraulic indexing mechanism of the drive shaft 50. The machine is then started exactly as in the previous instance, except that the spindle drive motor 5| remains idle. Stopping the machine is effected automatically by the counter -.or timer through the medium of the switch I39.

A shaft may also be polished by reciprocating it relative to the tool without either rotation or indexing. In this case, therefore, the clutch lever is set in the position to connect the spindle driving motor 5| with the drive shaft 50. The motor, however, is not operated; hence neither the drive shaft nor the work is rotated. Reciprocation of the carriage is effected in the usual way to effect relative movement of the tool and work in a straight line. I

It will be apparent from the foregoing that the invention provides a machine of novel and improved construction for dressing external cylindrical surfaces to a true contour and smooth finish. The machine is adapted to effect relative rotational and reciprocatory motion between an elongated cylindrical work piece and an external honing tool in a manner such that the tool is caused to act uniformly over the entire surface area to be dressed, thereby removing all high spots and irregularities and producing an extremely smooth accurate surface finish. The machine may be readily adjusted to handle work pieces of widely varying lengths.

The invention also provides a reciprocatory machine tool carriage of novel and advantageous construction. The carriage is fabricated from sheet or plate stock which reduces the weight to a minimum without sacrifice of rigidity. Due to the light weight of the carriage, it may be reciprocated at relatively high speeds without placing undue strain on the framework or driving mechanisms. Further reduction in the weight of reciprocating parts is obtained by the provision of novel means for operatively connecting a rotatable member on the reciprocating carriage supporting fixture mounted on said base, a cylindrical abrasive tool supported by said fixture, a headstock and a tailstock on said carriage having centers for supporting a work piece concentrically of said tool and with its axis parallel tothe reciprocating path of the carriage, means for reciprocating said carriage to traverse the work past the tool, a motor mounted on said base, and means operatively connecting said 'motor with the headstock center for rotating the work piece during the reciprocation of said carriage, said connecting means including a splined shaft driv ingly connected with said motor and extending substantially parallel to the reciprocatory path of the carriage, and a train of gears carried by said carriage for movement therewith, one of said gears being rigid with the headstock center and another of said gears having a slidable nonrotatable relation with said shaft.

2. In a machine for dressing external cylindrical surfaces, in combination, an elongatedhorizontally disposed base, a carriage supported for reciprocation longitudinally of the base, a'tool supporting fixture mounted 'onsaid. base,'a cylindrical abrasive tool supported by said" fixture, a headstock and a tailstock on said" carriage for supporting a Work piece concentrically of said tool and with its axis parallel to thereciproca'ting path of the carriage, said headstock havinga spindle drivingly connected withthe work piece,

means for reciprocating said carriage to traverse the work past the tool, a splined shaft 'journaled at one end on said base underlyingthe carriage and extending substantially parallel-to its reciprocatory path, a train of gears supported on said carriage for movement therewith,one of said gears being rigid withtne headstock spindle and' another of said gears having a slidable' nonro tatable relation'with said shaft; and'meansfor" driving said shaft to rotate the'work piece relative to said tool.

3. In a machine for'dressing external cylindrical surfaces, in combination, an elongatedhorizontally disposed base, a carriage supported for reciprocationlongitudinally of the base, a tool supporting fixture mounted on said base, a. cylindrical abrasive tool supported by said fixture, a

headstock and a tailstock on said'carriage for supporting a work piece concentrically of'said' tool and with its axis parallel to the reciprocating path of the carriage, said headstock having a rotatable spindle drivingly connected with the work piece, means for reciprocating said carriage to traverse the work past the-tool, a splined shaft journaled at one end on said base underlying the carriage and extending substantially parallel to its reciprocatory path, a train of gears supported on said carriage for movement therewith, one of said gears being rigid with the headstock spindle and another of said gears having a slidable non- .rotatable relation with said shaft, first poweractuated means operative to drive said shaft for imparting continuousrotation to the work piece, a second power-actuated means operative to drive said shaft intermittently to index the work piece, and manually operable means for rendering said power-actuated means effective selectively.

4. In a machine for dressing external cylindrical surfaces, in combination, an elongated horizontally disposed base, a carriage supported for reciprocation longitudinally of the base, a tool supporting fixture mounted on said base, a cylindrical abrasive tool supported by said fixture, a headstock and a tailstock on said carriage for supporting a work piece concentrically of said tool and with its axis parallel to the reciprocating path of the carriage, said headstock having a spindle for rotating the work piece, means for reciprocating said carriage to traverse the work past the tool, a splinedshaft journaled at one end on said base underlying the carriage and extending substantially to its reciprocatory path, a rotatable member on said carriage supporting the other end of said shaft, a train of gears supported on said carriage and movable therewith, one of said gears being rigid with the headstock spindle and another of said gears being rigid with said rotatable member and having a slidable nonrotatable relation with said shaft, and a motor on the base'for driving said shaft to rotate the work piece relative to said tool.

5. In a honing machine, in combination, an elongated base, a carriage mounted for reciprocation on said base, a rotatable element on said carriage, means for rotating said element including a motor mounted on said base, a splined shaft drivingly connected with said motor and extending substantially parallel to the reciprocatory path of the carriage, a stationary bearing on said base supporting one end of said shaft, means for supporting the other end of said shaft on said carriage, said' supporting means comprising a tubular member adapted to receive the shaft in telescoping relation, means rotatably supporting said member on the carriage, and means on the carriage drivingly connecting said shaft with'said rotatable element.

6. In a honing machine, in combination, an elongated base, a carriage mounted for reciprocation on said base, a rotatable element on said carriage, means for rotating said element including a motor mounted on said base; a splined shaft drivingly connected with said motor and extending substantially parallel to the reciprocatory path of the carriage, a stationary bearing on said base supporting one end of said shaft, means providing a bearing for the other end of said shaft comprising a tubular member rotatably supported on said carriage and adapted to receive the shaft in telescoping relation, said member having a sliding nonrotatable relation with the shaft, and a train of gears for drivingly connecting said shaft with said rotatable element including a gear rigid with the rotatable element and another gear rigid with said tubular member.

7. In a honing machine, in combination, an elongated base, a carriage mounted for reciprocation on said base, a rotatable element on said carriage, means for rotating said element including a motor mounted on said base, a splined shaft drivingly connected with said motor and extending substantially parallel to the reciprocatory path of the carriage, a stationary bearing on said base supporting one end of said shaft, means providing a bearing for the other end of said shaft comprising an elongated tubular member adapted to receive the shaft in telescoping relation, and antifriction bearings rotatably supporting said member at spaced points on said carriage.

8. In a machine of the character described, in combination, a reciprocatory carriage comprising, a rectangular upper box-like frame fabricated from flat plates, said frame having side walls, end walls and a bottom wall, a slot in said bottom wall extending longitudinally thereof for a substantial portion of its length, a lower frame also fabricated from flat plates having side walls, end walls and a bottom wall, said lower frame being of substantially the same width as said slot and disposed in registration therewith, transverse stiffening members interposed between the side walls of said lower frame, and outwardly projecting gusset plates extending between the side walls of said lower frame and the bottom wall of said upper frame, all of said parts being welded together to form a rigid structure of relatively light weight.

9. In a machine for effecting rapid reciprocation between a honing tool and the cylindrical surface of a work piece, in combination, a support for the tool, a support for the work piece, and a reciprocatory carriage for one of said supports comprising, a rectangular upper box-like frame fabricated from flat plates, said frame having side walls, end walls and a bottom wall, a slot in said bottom wall extending longitudinally thereof for a substantial portion of its length, a lower frame also fabricated from flat plates having side walls, end walls and a bottom wall, said lower frame being of substantially the same width as said slot and disposed in registration therewith, inverted generally U-shaped stiffening members interposed between the side walls of the lower frame, and gusset plates extending between the side walls of the lower frame and the bottom wall of the upper frame, all of said parts being welded together to form a rigid structure of relatively light weight.

10. In a machine for dressing the cylindrical surface of a work piece wherein the work piece is rapidly reciprocated relative to a stationarily supported honing tool, the combination of a reciprocatory carriage for suporting the work comprising, a rectangular upper box-like frame fabricated from flat plates, said frame having side walls, end walls and a bottom wall, a slot in said bottom wall extending longitudinally thereof for a substantial portion of its length, a lower frame also fabricated from flat plates having side walls, end walls and a bottom wall, said lower frame being of substantially the same width as said slot and disposed in registration therewith, transverse stiffening members interposed between the side walls of said lower frame, outwardly projecting gusset plates extending between the side walls of said lower frame and the bottom wall of said upper frame, all of said parts being welded together to form a rigid structure of relatively light weight, an extension formed integrally with said frames at one end of the carriage, a headstock supported on said extension, a bed plate mounted over said slot and removably secured to the bottom wall of said upper frame, and a tailstock adjustably supported on said bed plate for movement toward and from said headstock.

11. In a machine for dressing the cylindrical surface of a work piece by a rapid reciprocation of the work piece relative to the tool, the combination of a reciprocatory carriage for supporting the work piece comprising, a rectangular upper box-like frame fabricated from fiat plates, said frame having side walls, end walls and a bottom wall, a slot in said bottom wall extending longitudinally thereof for a substantial portion of its length, a lower frame also fabricated from flat plates having side walls, end walls and a bottom wall, said lower frame being of substantially the same width as said slot and disposed in registration therewith, inverted generally U-shaped stiffening members interposed between the side walls of the lower frame, all of said parts being welded together to form a rigid light-weight structure, said stiffening members being spaced apart longitudinally of the lower frame to form therewith a series of upwardly opening pockets for the reception of liquid coolant, and slots in one side wall of the lower frame providing outlets for said pockets.

12. In a honing machine of the type in which the work piece is rapidly reciprocated relative to a honing tool, the combination, of a reciprocatory carriage for the work piece comprising, a rectangular upper box-like frame fabricated from fiat plates, said frame having side walls, end walls of the lower frame and the bottomwall of the upperframe, all of said parts being welded together to form a rigid. light-weight structure, and bearing supporting brackets disposed within said upper frame at spaced points along the side walls thereof, said brackets being welded to the side and bottom walls of the frame to constitute integral units of the structure.

13. In a machine for dressing cylindrical surfaces, in combination, an elongated base, guide bars extending longitudinally of the base, a carriage supported for reciprocation on said guide bars, a cylindrical abrasive tool stationarily supported on said base and disposed above the reciprocatory path of said carriage, means on the carriage for supporting a cylindrical work piece in operative relation to sa d tool and with its axis substantially parallel to the reciprocatory path of the carriage, means for rotating the work piece, pressure fluid-actuated means for imparting continuous reciprocatory motion to said carriage to traverse the rotating work piece past sa d tool, valve means controlling said pressure fluid actuated means to limit the range of movement of said carriage, electrically operated means for actuating said valve means, and means for controlling said electrically operated means including a pair of limit switches supported on said base for operative engagement by said carriage at the extreme limits of its movement, said switches being adjustable relative to each other to vary the range of carriage movement.

14. In a machine for dressing cylindrical surfaces, in combination, an elongated base, guide bars extending longitudinally of the base, a carriage supported for reciprocation on said guide bars, a cylindrical abrasive tool stationarily supported on said base and disposed above the reciprocatory path of said carriage, means on the carriage for supporting a cylindrical work piece in operative relation to said tool and with its axis substantially parallel to the reciprocatory path of the carriage, means for rotating the work piece, pressure fluid-actuated means for imparting continuous reciprocatory motion to said carriage to traverse the rotating work piece past said tool, valve means controlling said pressure fluidactuated means to limit the range of movement of said carriage, electrically operated means for actuating said valve means, automatic means for controlling said electrically operated means including a pair of limit switches supported on said base for operative engagement by said carriage at the extreme limits of its movement, and means for controlling said electrically operated means independently of said limit switches comprising a second pair of switches, and manually operable means for operating said last mentioned switches selectively.

15. In a honing machine, in combination, an elongated horizontally disposed base, a carriage supported for reciprocation longitudinally of said base, power-actuated means for reciprocating said carriage, a rod extending longitudinally of said base and supported at opposite ends on the side walls of the base, limit switches for controlling said power-actuated means adjustably supported on said rod for engagement by said carriage at the extreme limits of its movement, and means for supporting said rod at an intermediate point including a member mounted on said base, said member being retractible to permit movement of either limit switch past said intermediate point.

16. In a honing machine, in combination, an elongated horizontally disposed base, a carriage supported for reciprocation longitudinally of said base, power-actuated means for reciprocating said carriage, a rod extending longitudinally of said base and supported at opposite ends on the side walls of the base, limit switches for controlling said power-actuated means adjustably supported on said rod for engagement by said carriage at the extreme limits of its movement, and means for supporting said rod at an intermediate point including a member mounted on said base, said member being shiftable longitudinally of the rod to permit unrestricted adjustment of said limit switches.

17. In a honing machine, in combination, an elongated horizontally disposed base, a carriage supported for reciprocation on said base, poweractuated means for imparting continuous reciprocating motion to said carriage, a member extending transversely across the base and adjustably secured thereto, resilient pads on said member, and adjustable elements on said carriage engageable with said pads to positively limit the movement of the carriage.

18. In a machine tool, in combination, a base, guide bars mounted on said base in parallel spaced relation to form a guideway, a carriage adjustably supported on said guideway for reciprocation thereon, a rotatable element on said carriage, means for rotating said element including a motor mounted on said base, a splined shaft drivingly connected with said motor and extending substantially parallel to the reciprocatory path of the carriage, and means for supporting said shaft so as to avoid any possibility of binding when the carriage is adjusted on the guideway comprising, a stationary bearing mounted on said base for supporting one end of the shaft, and a bearing on said carriage and reciprocable therewith for supporting the other end of the shaft.

ALBERT M. JOHNSON. WALTER M. FAIRBAIRN.

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