Reciprocating Mechanism

1. Field of the Invention

The present invention generally relates to the field of reciprocating mechanisms and, in particular, the present invention is concerned with hand held reciprocating mechanisms for driving an abrasive tool.

2. Description of the Prior Art

Hand held reciprocating mechanisms such as profilers for driving abrasive tools are known. The prior art devices are deficient in that they will not provide long life and are susceptible to heavy wear and early failure caused by transverse loads applied to the reciprocating tool. Examples of reciprocating mechanisms in the prior art are disclosed in U.S. Pat. Nos. 2,690,081 and 3,626,768. These patents are relevant to the Applicant's invention in that they represent the closest prior art for reciprocating mechanisms for finishing irregular surfaces such as dies and the like.

3. Prior Art Statement

The aforementioned prior art, in the opinion of the Applicant and the Applicant's Attorney, represents the closest prior art of which the Applicant and his Attorney are aware.

The present invention, which will be described in greater detail hereinafter comprises a hand held reciprocating mechanism for driving an abrasive tool for finishing dies and other irregular surfaces. The mechanism comprises a housing, a tool holding assembly supported for reciprocation by the housing, and a drive mechanism comprising a drive shaft rotating on an axis perpendicular to the direction of reciprocation. The drive shaft is supported in the housing by a pair of axially spaced bearings, and a crank pin is attached to the drive shaft having a selectively adjustable crank arm to adjust the amount of reciprocating motion. A connecting rod is operatively coupled between the crank pin and the tool holding assembly. A tool support bushing having a central bore is supported at an externally threaded inner end by the housing. The tool support bushing slidingly supports for reciprocation the tool holding assembly. A tool support housing surrounds and is rotatingly supported by an outer portion of the tool support bushing. The tool support housing includes an inner end and an enlarged outer end. A retaining ring is provided for axially securing the tool support housing to the tool support bushing which permits rotation of the tool support housing relative to the tool support bushing while preventing axial movement of the tool support housing. The retaining ring allows assembly of the tool support housing to the tool support bushing by the insertion of the tool support bushing into the tool support housing inner end leaving the enlarged outer end unobstructed for the formation of a slot. A pair of opposed flats are formed on the tool holding assembly to snugly abut the slot with the slot and opposed flats extending substantially transversely across the enlarged outer end. This provides a large bearing area between the tool holding assembly and the tool support housing to housing to accommodate heavy transverse loads without excessive wear. A shield covering the end of the tool holder assembly prevents the entry of chips and abrasives into the reciprocating mechanism which adds to the durability of the device.

It is therefore a primary object of the present invention to provide a new and improved reciprocating mechanism.

It is a further object of the present invention to provide a reciprocating mechanism for profiling and finishing irregular surfaces such as dies.

It is yet another object of the present invention to provide a reciprocating mechanism for profiling irregular surfaces that has enlarged bearing areas to absorb transverse loads without excessive wear.

It is another object of the present invention to provide a reciprocating mechanism for finishing irregular surfaces that includes a shield for preventing the entry of abrasives and chips into the area between wear surfaces.

Further objects, advantages, and application of the present invention will become apparent to those skilled in the art of reciprocating mechanisms when the accompanying description of one example of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawing.

The description herein makes reference to the accompanying drawing wherein like reference numbers refer to like parts throughout the various several views, and wherein:

FIG. 1 illustrates a cross sectional view of the reciprocating mechanism of the present invention;

FIG. 2 illustrates a cross sectional view of the tool holding assembly of the present invention taken along the lines 2--2 in FIG. 1;

FIG. 3 is a cross sectional view through the tool holding assembly taken along the lines 3--3 of FIG. 1; and

FIG. 4 illustrates an exploded view of the support bushing, tool holding assembly, and the tool support housing.

Referring now to FIG. 1 of the drawing, there is illustrated at 10 one example of the present invention in the form of a hand held reciprocating mechanism or profiler. The hand held reciprocating mechanism 10 comprises a housing 12, a tool holding assembly 14, and a drive mechanism 16 which includes a drive shaft 18 rotating on an axis 20. The tool holding assembly 14 is supported for reciprocation by the housing 12 and reciprocates in a direction perpendicular to the axis 20.

The drive shaft 18 is supported in the housing 12 by a pair of axially spaced bearings 22, and a crank pin 24 is provided at an inner end of the crank shaft. The crank pin 24 is supported by an eccentric plug 26 which is rotatable and provides a selectively adjustable reciprocating motion. A connecting rod 28 operatively couples the crank pin 24 to the tool holding assembly in a manner which will be described in greater detail subsequently.

A tool support bushing 30 is provided which has a central bore 32 and is supported by an externally threaded inner end 34 which engages a complementary threaded bore 36 in the housing 12.

A tool support housing 38 is slidingly and rotatingly supported by the tool support bushing 30 by a support bushing outer portion 40, and is axially retained on the support bushing 30 by a retaining means 42 which will be described in greater detail subsequently. The tool support housing 38 includes an inner end 44 and an enlarged outer end 46. The retaining means 42 for axially securing the tool support housing 38 to the tool support bushing 30 and allowing rotation of the tool support housing relative to the tool support bushing comprises a longitudinal bore 48 formed in the tool support housing 38 for rotatingly engaging the support bushing outer portion 40, and a first groove 50 extending radially outward from the longitudinal bore 48. A second groove 52 is formed in the support bushing 30 and extends radially inward from the support bushing outer portion 40 and is axially aligned with the first groove 50. A retaining ring 54 is slidingly engageable with the first and second grooves 50, 52, and a gap 56 (as shown in FIG. 4 of the drawing) is formed in the circumference of the ring 54 to allow the ring to be squeezed radially inward for insertion into the longitudinal bore 48. The retaining ring 54 in a relaxed state is expandable into the first groove 50 partially radially filling the first groove. The retaining ring 54 is radially expandable past the relaxed state outward into the first groove 50 to allow the ring to slidingly pass over the bushing outer portion 40 and enter the second groove 52. Upon entering the second groove 52 the retaining ring 54 simulatneously engages the first and second grooves 50, 52 to prevent axial movement of the tool support housing 38 relative to the tool support bushing 30 while allowing free angular rotation of the tool support housing relative to the tool support bushing. A chamfer 58 formed on an outer end of the tool support bushing 30 aids in the engagement of the tool support bushing with the retaining ring 54 and the outward expansion of the retaining ring to fit over the bushing outer portion 40.

Referring now to FIG. 2 of the drawing, the tool holding assembly 14 comprises a tube 60 having a connecting rod end 62 and a threaded tool holder end 64 which includes a thread 66 formed internally along the tool holder end. The connecting rod end 62 of the tube 60 includes a first spherical socket 68 with an outwardly enlarging aperture 70 to provide clearance for the connecting rod 28 to swivel. The connecting rod 28 includes an enlarged spherical end 72 formed at the end of a rod 74. The rod 74 extends through the outward enlarging aperture and engages a crank pin opening 76 formed in the crank pin 24. A threaded bore 78 is formed in the crank pin 24 to receive a threaded fastener 80 which secures the rod 74 to the crank pin 24. A second spherical socket 82 is formed in the enlarged spherical end 72 to snugly receive a ball 84. A spring seat 86 includes a third spherical socket 88 to abut the ball 84. A tool support 90 includes a threaded end 92 to threadingly engage the threaded tool holder end 64. A biasing means comprising a spring 94 extends between the tool support 90 and the spring seat 86 to bias the spring seat 86 against the ball 84 and the ball 84 into abutment with the second spherical socket 82 and the enlarged spherical end into abutment with the first spherical socket 68. The biasing spring 94 limits the load that can be imposed upon the connecting rod 28 and prevents stalling of the drive motor and any resulting damage to the reciprocating mechanism when a load exceeding the biasing force is applied to the tool support 90. With the ball 84 positioned between and abutting the second and third sperical sockets the swiveling motion of the connecting rod is distributed one half between the ball and the second spherical socket and another half between the ball and the third sperical socket substantially reducing wear.

The tool support 90 as shown in FIG. 3 of the drawing includes a tool engaging end 96 having a pair of opposed flats 98 formed thereon. As shown in FIG. 2 of the drawing, a tool engaging bore 100 is provided to receive a shank of a tool (not shown). A threaded bore 102 intersects the tool engaging bore 100 and receives a threaded screw 104 to secure the tool in place.

As shown in FIG. 1 a shield 106 is provided to prevent the entry of chips and abrasives into the reciprocating mechanism. A means 108 is provided for attaching the shield 106 to the tool support 90. The means 108 comprises a screw 110 threadingly engaging a threaded bore 112 formed in the tool support 90, with the head of the screw 111 abuting the shield 106 to hold it in abutment with the tool support 90.

As shown in FIG. 4, a slot 110 is formed in the enlarged outer end 46 to snugly and slidingly abut the pair of opposed flats 98 providing transverse support for the tool support 90 and enabling the reciprocating mechanism to accommodate heavy transverse loads without experiencing excessive wear. The pair of opposed flats supported by the slot 110 together with the ball 84 resting in the second and third spherical seats and the enlarged spherical end 72 abutting the first spherical socket add substantially to the durability and wear resistance of the reciprocating mechanism of the present invention.

Prior art profilers are prone to have substantial wear and early failure because of a rather great distance between the bearing surfaces that support transverse tool loads and the tool. Also, the amount of bearing surface available to support the transverse load is limited in prior art devices. The present invention, by utilizing the retaining means 42, allows the use of a generous bearing surface for carrying transverse loads that is placed adjacent the tool. This reduces the over-hung load and increases the amount of bearing area to carry the load as well. This results in a substantial increase in the operating life of the reciprocating mechanism.

As shown in FIG. 3 of the drawing, a handle 120 is provided for rotating the tool support 90. The handle 120 comprises a body 122 secured to the tool support housing 38. The outer edges 124 are knurled for easy gripping of the handle 120 by the operator's hand. A pair of finger engaging projections 126 are provided to give the operator added leverage and convenience in rotating the tool holding assembly 14 with his fingers.

It can thus be seen that the present invention has provided a new and improved reciprocating mechanism for finishing dies etc. having an irregular surface. It can be readily seen by the skilled artisan that using the teachings of the present invention a reciprocating mechanism may be had that has superior wear resistance and utility and can be manufactured at a reasonable cost.

It should be understood by those skilled in the art of profilers or reciprocating mechanisms that other forms of the Applicant's invention may be had, all coming within the spirit of the invention and the scope of the appended claims.