Abstract:
A mechanism for honing non round cylinder bores includes a tool body rotatable around a nonrotatable cam with a non round peripheral cam surface and a plurality of honing stones carried by supports for generally radial movement in the tool body. In a preferred embodiment, the supports are swing arms pivotally mounted so that the honing stones follow generally radially oriented arcuate paths determined by cam followers carried by the swing arms. A separately controlled expansion actuating rod axially adjusts expansion shoes that wedge outward stone shoes carried by the swing arms to progressively remove stock from the cylinder and to compensate for wear of the honing stones. Assembly with an associated machine adapter supports the honing mechanism and connects with a conventional honing machine to drive and orient the assembly for accurately honing non round cylinder bores.

Description:
TECHNICAL FIELD 
     This invention relates to mechanisms for honing non round cylinder bores and to an adapter for connecting the honing mechanism with a conventional honing machine. 
     BACKGROUND OF THE INVENTION 
     Various mechanisms have been used for honing the bores of elliptical and other non round cylinders used in a few internal combustion engines and potentially usable in other devices. Some of these mechanisms apply constant hydraulic pressure in the process of metal removal. This method has a tendency to follow the original bore geometry rather than correcting it to a desired configuration. Some methods employ three dimensional grinding which generally requires excessive cycle time for commercial production use. U.S. Pat. No. 5,681,210, assigned to the assignee of the present invention, describes a mechanism including a barrel cam external to a conventional honing machine as the principal actuator for the contouring and expansion of honing stones. 
     SUMMARY OF THE INVENTION 
     The present invention provides a honing mechanism in which a precision camshaft is located inside a tool body to minimize the actuation linkage and directly drive the honing stones in an elliptical or other desired non round contour as they revolve around the camshaft. A separate vertically movable actuator rod drives expansion shoes that cam associated stone carrying shoes outward and provide steady, high pressure with a small expansion movement for progressively removing stock as well as for stone wear compensation. Preferably, the honing stones are carried on swing arms which facilitate a large and rapid reciprocating movement of the honing stones and their assemblies. A center fed coolant passage feeds coolant to the internal mechanism, which has limited external communication, to maintain an outward coolant flow that keeps chips and abrasive from entering the enclosure and minimizes wear of the precision actuating members. 
     These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a cross-sectional view through the central axis of a combined honing mechanism and machine adapter assembly according to the invention; 
     FIG. 2 is an enlarged cross-sectional view of the honing mechanism in the assembly of FIG. 1; 
     FIG. 3 is an external side view of the honing mechanism of FIG. 2; 
     FIG. 4 is a lower end view of the honing mechanism of FIG. 3; 
     FIG. 5 is a transverse cross-sectional view from the line  5 — 5  of FIG. 3; 
     FIG. 6 is a transverse cross-sectional view from the line  6 — 6  of FIG. 3; 
     FIG. 7 is a transverse cross-sectional view from the line  7 — 7  of FIG. 3; 
     FIG. 8 is a partially exploded pictorial view showing construction of the swing arm assemblies; 
     FIG. 9 is an exploded pictorial view showing an alternative embodiment of swing arm assembly; and 
     FIG. 10 is an exploded pictorial view of the swing arm assembly of FIG. 9 viewed from the opposite direction. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIG. 1 of the drawings in detail, numeral  10  generally indicates an assembly of a mechanism  12  for honing non round cylinder bores and a machine adapter  14  for driving the mechanism and connecting the assembly with a commercial honing machine, not shown, having a tool size adjustment capability concentrically located inside the honing machine spindle. The adapter  14  includes a stationary central connector  16  and a surrounding rotatable coupling  18 . The coupling is adapted to be supported by and rotatably connected with a drive spindle, not shown, of the associated honing machine. 
     Coupling  18  is connected with a gear  20  that is rotatably supported by bearings in a stationary gearbox  24 . In use, the gearbox  24  is attached to the honing machine frame, not shown, in a manner that allows it to move vertically on guide rods, not shown, but prevents it from rotating. Gearbox  24  is connected by a key  26  with a hollow camshaft  28  of the honing mechanism  12 , to be subsequently described, and thus holds the camshaft against rotation relative to the gearbox  24 . 
     Rotatable gear  20  is drivably connected through an offset gear cluster  30  with a drive gear  32 . The drive gear is, in turn, drivably connected by a key  34  with a hollow tool body  36  forming part of the honing mechanism  12 . The tool body  36  is formed as a hollow shaft which is rotatably supported on bearings within the gearbox  24  of the machine adapter  14 . 
     Referring additionally to FIGS. 2-8 of the drawings, the lower end of the tool body  36  is expanded outward to form a cylindrical housing  38  having an open lower end closed by a retainer plate  40 . 
     Mechanism  12  includes a stationary cam  42  forming the lower end of the hollow camshaft  28  and rigidly supported in gearbox  24  by a hex nut  44 . Stationary cam  42  and hollow camshaft  28  are indexed with respect to the honing machine, not shown, by key  26 . The profile of stationary cam  42  is generated for a unique non round cylinder bore size and shape. The geometric relationship of other parts in the mechanism  12  influences the profile of the stationary cam  42 , and causes its profile to be different from that of the resulting cylinder bore. 
     The rotating tool body  36  is located around stationary cam  42  and hollow camshaft  28 . Ball bearings  48  and  50  are mounted on and secured to tool body  36  by lock washer  52  and bearing lock nut  54 . Ball bearings  48  and  50  are, in turn, located in respective bores in gearbox  24 . Tool body  36  is driven by gear  32  through the gears  30 ,  20  from the coupling  18 . In this manner, machine adapter  14  transmits a rotating input, which is inside the grounding members (gearbox  24 ), to a rotating output (tool body  36 ) which is outside the grounding members (hollow camshaft  28  and stationary cam  42 ). 
     Retainer plate  40  attaches to the bottom of tool body  36  with four screw fasteners  56  (FIG.  4 ). Additionally, retainer plate  40  contains four equally spaced holes  58  that are in line with four equally spaced holes  60  (FIG. 8) in tool body  36 . Four swing arms  62  are press fitted with a protruding pin  64  at each end. Two pins  64  are positioned in line and form an axis of rotation for each swing arm  62 . The upper pin  64  fits into one of the four equally spaced holes  60  in tool body  36 . Lower pin  64  fits into the opposing hole  58  in retainer plate  40 . When installed in housing  38  of tool body  36 , the four swing arms  62  are free to pivot about their respective axes. 
     A needle bearing  66  is press fitted into the center of retainer plate  40 . A bearing race  68  on the lower end of hollow camshaft  28  is piloted inside of needle bearing  66 . Needle bearing  66  maintains a coaxial relationship between the axis  70  of stationary cam  42  and the housing  38  of tool body  36 . 
     Using current bonding practices, a honing stone  72  is attached to each stone shoe  74  which, in turn, is slip fitted into a rectangular opening  76  in each swing arm  62 . Two cam follower rollers  78  are rotatably mounted in each of four expansion shoes  80  on cam roller pins  82 . Each expansion shoe  80  slip fits into a pocket  84  in stone shoe  74 . Two wedge surfaces  86  on the outside of each expansion shoe  80  cooperate with two similar wedge surfaces  88  on the inside pocket of each stone shoe  74 . 
     When assembled, a vertical slot  90  in each expansion shoe  80 , a horizontal slot  92  in each stone shoe  74 , and a hole  94  in the respective swing arm  62 , are all in line. A shoe retaining pin  96  is press fitted into hole  94  in each swing arm  62  and slip fitted through horizontal slot  92  in the associated stone shoe  74  and vertical slot  90  in associated expansion shoe  80 . The shoe retaining pin  96  ensures that swing arm  62  moves in unison with its expansion shoe  80 . Any change in distance between the axis of cam follower pin  82  (on expansion shoe  80 ) and the axis of rotation of swing arm  62  would cause a change in the geometric relationship used to generate the profile of stationary cam  42 . Consequently, the profile of the cylinder being honed would be changed. 
     The top and bottom of each stone shoe  74  is press fitted with a spring anchor pin  98 . An extension spring  100  is connected between each pair of adjacent spring anchor pins  98  forming a closed “parallelogram ” at both the top and bottom of the non round cylinder bore honing mechanism  12 . The eight extension springs  100  keep all four pairs of cam follower rollers  78  in contact with the stationary cam  42 . Additionally, the extension springs  100  retain all four stone shoes  74  within their respective swing arms  62 . 
     As tool body  36  is driven in a clockwise direction (when viewed from the top) by the honing machine spindle through machine adapter  14 , the two cam follower rollers  78  on each expansion shoe  80  follow the profile of the stationary cam  42 . The two cam follower rollers  78  are mounted to expansion shoe  80 , which in turn is constrained by stone shoe  74 . Because both shoes are pinned to swing arm  62  by shoe retaining pin  96 , swing arm  62  oscillates about the axis formed by the centerline through pins  64  in addition to rotating about the axis of the honing machine spindle  70 . As cam follower rollers  78  rotate against stationary cam  42 , the resulting combination of motions generates the desired bore shape at the face of honing stone  72 . Additionally, as it rotates, the entire assembly shown in FIG. 1 oscillates up and down while the mechanism  12  is within the cylinder bore and produces a crosshatched honing pattern. 
     As the four stone shoes  74  are alternately expanded and contracted by cam follower rollers  78  tracing the surface of stationary cam  42 , the length of the four springs  100  that make up each “parallelogram ” remains nearly constant. As one spring anchor pin  98  is expanding outward, the spring anchor pins  98  on both sides of it are contracting inward at nearly the same rate. Consequently, spring force on the mechanism is nearly constant at all rotation angles. 
     The upper end of an expansion control rod  102  is connected by connector  16  to a controllable adjustment mechanism inside the honing machine spindle not shown. An elliptical (or non round) shaped thrust plate  104  extends around stationary cam  42  and is pinned to the expansion control rod  102  by rod pin  106 . Pin  106  passes through a vertical clearance slot  108  in stationary cam  42 . 
     As stock removal or stone wear occurs, expansion control rod  102  and thrust plate  104  are driven downward by the expansion adjustment mechanism of the honing machine, not shown. Thrust plate  104  engages a notch  110  in each of the four expansion shoes  80  and drives them in the same direction simultaneously. As expansion shoes  80  are forced downward, wedge surfaces  86 ,  88  drive stone shoes  74  horizontally outward to remove more stock or compensate for wear on honing stones  72 . 
     Before the start and after the finish of the honing operation, expansion control rod  102  is moved upward. Thrust plate  104  and all four expansion shoes  80  move in the same direction. Upward movement of the wedge surfaces  86  on expansion shoes  80  allows extension springs  100  to contract all four stone shoes  74  so that the non round cylinder bore honing mechanism  12  can be inserted or withdrawn from the cylinder bore without scratching its surface finish. 
     All openings on the exterior of the non round cylinder bore honing mechanism  12  are intentionally kept to a minimum. Lubricant containing coolant is fed into gearbox  24  through a port  112 . An annular flow path  114  directs the coolant down to the cylindrical housing  38  of the non round cylinder bore honing mechanism  12 . Since openings in mechanism  12  are kept to a minimum, an outward coolant flow can be maintained. In addition to providing lubricant to all moving parts inside of the cylindrical housing  38 , the outward flow direction deters abrasive contaminants from entering and prematurely wearing out the moving parts. 
     To prevent coolant from traveling up into machine adapter  14  through the space  115  between hollow camshaft  28  and tool body  36 , a rotating type seal  116  is provided. A witness hole  118  in tool body  36  is located above rotating seal  116  in case the latter should leak. 
     FIGS. 9 and 10 show an alternate arrangement where stone shoe  74  is replaced with an improved design stone shoe  120 . Locating wedge surfaces  86  on the exterior faces of stone shoe  120  makes the part easier to manufacture. To be compatible with stone shoe  120 , expansion shoe  80  must also be replaced. FIGS. 9 and 10 show the modified expansion shoe  122  that replaces expansion shoe  80 . All other parts are interchangeable between the two designs. Function and operation of the expansion mechanism is the same for both versions. 
     While the invention has been described by reference to certain preferred embodiments, it should be understood that numerous changes could be made within the spirit and scope of the inventive concepts described. Accordingly it is intended that the invention not be limited to the disclosed embodiments, but that it have the full scope permitted by the language of the following claims.