MXPA97002299A

MXPA97002299A - Assembly and assembly method of follower of l

Info

Publication number: MXPA97002299A
Application number: MXPA/A/1997/002299A
Authority: MX
Inventors: Mang Josef
Original assignee: Emerson Electric Company
Priority date: 1996-03-27
Filing date: 1997-03-26
Publication date: 1998-04-01

Abstract

A cam follower assembly assembly includes a mounting member, such as a rotary indexer output mounting plate, having first and second cam follower mounting surfaces and a hole between the mounting surfaces and, a follower cam mounted on the mounting member wherein the cam follower includes a mounting arrow received in the hole of the mounting member and having a cam follower member rotatably positioned on a first arrow end next to the first mounting surface of cam follower in a manner to be coupled by a cooperating cam rail and a second arrow end proximal to the second cam follower mounting surface. The second end of the mounting arrow includes a threaded hole extending from a second end surface substantially coaxial with the longitudinal axis of the mounting arrow. The mounting assembly further comprises a screw having an elongated head and a threaded shaft received screwed into the threaded hole of the cam follower mounting shaft and a washer positioned between the elongated head of the screw and the second mounting surface of cam follower. When the screw is screwed into the threaded hole of the cam follower mounting arrow to secure the cam follower on the mounting member, the bending forces on the mounting shaft are substantially reduced to improve perpendicular alignment in this way of the mounting arrow with respect to the cam follower mounting surfaces and therefore the cooperating cam rail, thereby improving the service life of the cam follower and the rail of the cam follower.

Description

ASSEMBLY AND METHOD OF MOUNTING THE CAM FOLLOWER FIELD OF THE INVENTION The present invention relates to the mounting of cam followers in relation to a mounting member such as, for example, an indexed rotary pulse output mounting plate and, more particularly, to an assembly and mounting method. cam follower that improves the positioning accuracy of the cam follower relative to the mounting member.

BACKGROUND OF THE INVENTION The cam operated by indexed rotary drives is in widespread use with machine tools u and other equipment for indexing a machine component, such as a machine tool dial plate or toothed conveyor belt, in predetermined rotary increments. Typical indexed rotary drives include an indexer output mounting plate connected to the machine component to be indexed in rotary increments. The indexer output mounting plate includes a plurality of cam followers that are placed in a circular array to cooperate with one or more cam tracks of an adjacent precision cam as the cam is rotated. The cam track (s) is (are) configured to impart a predetermined rotary indexing movement towards the indexer output mounting plate by means of the cam followers as the cam is rotated. Such indexed drivers are described in U.S. Patents 3,049,017 and 5,345,831. Cam followers used in the past in rotating indexed impellers had included a cylindrical mounting arrow having a shell or rotating cam follower member supported by friction supports on one end of the shaft to engage the cam track and external threads at the opposite end of the arrow by which the arrow is fixedly mounted on the indexer output mounting plate by means of a threaded fastening nut. To secure the cam follower in position, the clamp nut is threaded onto the external threads of the cam follower mounting arrow and is screwed down until it meets the indexer mounting plate surface to secure the follower of cam in position. Although the cam follower is ideally positioned with its mounting arrow shaft perpendicular to the indexer output mounting plate, the cam follower assembly technique described above has experienced problems in the past due to a lack of quadrature of the cam follower. Face of the retaining nut that engages the indexer output mounting plate. In particular, the face of the clamping nut is often not square with respect to the axis of the mounting arrow of the cam follower. As a result, when the clamping nut is screwed into the threaded mounting arrow of the cam follower and in engagement with the mounting plate, the non-square face of the clamping nut causes bending or bowing of the mounting arrow so that that the longitudinal axis of the arrow is no longer perpendicular to the mounting plate as desired. This bending or bowing of the arrow results in cam follower misaligned in relation to the precision cam track. A factor contributing to this lack of squareness of the face of the clamping nut has been the threaded pitch of the cam follower mounting arrow. Even if the face of the clamping nut is square, such a square is effective only at a point on the rotational axis of the thread. If the clamping nut is rotated, for example, 90 °, the clamping nut is no longer square due to the lead angle error in the thread. A technique adopted in the past in an attempt to reduce the problem of misalignment of the cam follower has involved precision grinding of the face of the clamping nut that engages the surface of the mounting plate to improve its perpendicularity to the arrow of mounting of the cam follower. However, this correction technique involves the consumption of additional time and costly machining operations of each of the clamping nuts. Furthermore, the machining operation may not be sufficiently precise and / or sufficiently consistent from one fastening nut to another to completely avoid the misalignment problem of the cam follower.

It is an object of the present invention to provide a method of mounting one or more cam followers on a mounting member, such as, for example, only one indexer output mounting plate, which overcomes the problems and disadvantages described above in present with respect to the positioning of the cam followers in relation to the mounting member. Another object of the present invention is to provide a cam follower assembly assembly that provides improved alignment of the cam follower with respect to a mounting member and therefore to a precision cam cooperating therewith.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a cam follower mounting assembly of a mounting member, such as a rotary impulse output mounting plate of the indexer, having first and second cam follower mounting surfaces and a hole between the mounting surfaces. The mounting assembly includes a cam follower having a mounting arrow received in the hole of the mounting member. The mounting arrow includes a cam follower member rotatably positioned on a first arrow end next to the first cam follower mounting surface and a second arrow end next to the second cam follower mounting surface. The second arrow end includes an internal threaded hole extending from an axial arrow end surface in substantially coaxial relationship with the longitudinal axis of the mounting arrow. The cam follower assembly assembly further comprises a mounting screw having a threaded shaft which is received threadedly in the threaded hole of the cam follower mounting shaft and a washer positioned between the screw and the second mounting surface of the cam follower. follower of cam. When the mounting screw is screwed into the threaded hole of the cam follower mounting arrow to secure the cam follower on the mounting member in accordance with a method embodiment of the present invention, the bending forces on the arrow of the cam follower are substantially reduced by virtue of the coaxial relationship of the threaded hole and the longitudinal arrow shaft to thereby improve the perpendicular alignment of the mounting arrow with respect to the mounting surfaces of the cam follower and thus both the cooperative cam lane. Due to the condition of the cam follower mounting arrow which is internally threaded, there is a larger surface for axial engagement with the side wall of the mounting member hole than with the externally threaded mounting arrows, which further contributes to the improved alignment. This improved alignment reduces the wear of the cam follower and the cam track and extends its maximum service life. In addition, the improved alignment provides a generally more stable cam follower, because it has an improved length-to-diameter ratio. The present invention will be described in greater detail in the following detailed description thereof taken with the following drawings.

DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective, partly exploded, view of a rotary indexed impeller having a plurality of cam followers (without mounting screws and washers) on an indexed impeller outlet mounting plate for coupling by a precision cam Figure 2 is a cross-sectional view of the impeller output mounting plate indexed with a cam follower mounted therein in accordance with one embodiment of the present invention. Figure 3 is an elevational view, partially in section, of the cam follower according to the invention.

DETAILED DESCRIPTION OF THE INVENTION Referring to Fig.1, a rotary indexed impeller 10 is shown for the purposes of illustration, but without limiting, the present invention. Figure 1 illustrates the cam follower assembly on the indexed impeller output mounting plate or member 12 of the rotary indexed impeller 10. The present invention is not limited to the practice with respect to rotary indexed impellers and instead it can be practiced with respect to a wide variety of machines and equipment employing one or more cam followers and one or more cams to control the movement of a component of the machine or equipment. The rotary indexed impeller 10 includes a cast iron or steel housing 14 on which is mounted a precision cam 16 having a pair of circumferentially extending cam rails 16a, 16b laterally spaced from the periphery of the cam. The cam rails 16a and 16b have a precision machined configuration selected to control the rotational movement of the output mounting plate or member 12 in a predetermined increasing manner or sequence as known. The precision cam 16 is mounted to an output driver shaft 22 mounted in the housing 12 by friction bearings 24 such as tapered roller bearings. . An arrow drive motor (not shown) is coupled to the input drive shaft to rotate the drive shaft 22 and the precision cam 16 mounted thereon. The plate or output mounting member of the indexer 12 is mounted on the housing by suitable friction bearings 26, such as ball bearings and bearing channels as shown in its exploded section of the plate or member 12. The plate or member of output assembly 12 includes a first cam follower mounting surface 12a formed on a bottom side thereof, Figure 2. The first cam follower mounting surface 12a is formed on a plate extension 13 formed integrally with or attached to the plate or main member 12. A plurality of second cam follower mounting surfaces 12b are formed by respective annular shoulders 30c of cylindrical spreading sections 30a machined into the uppermost main mounting surface 12c of the plate or member 12, Figure 2. The first and second cam follower mounting surfaces 12a, 12b are in parallel relation to each other. The first and second cam follower mounting surfaces 12a, 12b and the holes 30 are precision machined in order to accurately position the cam followers 50 relative to the cam tracks 16a, 16b to obtain a predetermined rotary indexing of the plate or mounting member 12. Each upper flare section 30a communicates with a cylindrical lower orifice section 30b to form a through hole 30 in the plate or mounting member 12. As best shown in FIG. 1, the through holes 30 are placed in a circular arrangement on the mounting plate or member 12 about a vertical rotary axis of the plate or member 12. The main output mounting surface 12c of the plate or member 12 is connected to a component 12 (not shown) of a machine tool or other equipment to be indexed in revolving increments. For example, the machine component may comprise a machine tool dial plate or a toothed wheel that is to be rotated in increments relative to fixed tool stations. The plate or member 12 includes a central plate opening 31 that receives fluid lines, power lines, etc., for the machine to be controlled. Referring to Figure 2, a cam follower 50 is shown on the plate or member 12 with the cam follower member 56 in a position that is engaged by the cam tracks 16a, 16b of the precision cam 16 (from Fig. 1). Each of the cam followers 50 comprises a spindle or generally cylindrical mounting shaft 52 received with close tolerance (for example, 0.000508 cm) in the cylindrical hole section 30b. The mounting spindle or shaft 52 includes a first end 54 proximate the first cam follower mounting surface 12a. A shell or cam follower member 56 is rotatably supported on the first end 54 by friction bearings 58, such as roller bearings loaded with grease, placed between an annular flange of relatively outer diameter 60 and by means of an annular flange of relatively small, internal diameter 62, both formed integrally on the end of the mounting arrow 54. A annular end plate 64 is snapped onto the end of the arrow 54 around the inner flange 62. The arrow end may include a hexagonal socket or other 66 to receive a key (not shown). In the practice of the invention, the cam follower member, the bearings, the bearing flanges and the end plate at the arrow end 54 may correspond in dimensions and tolerances to those present in the spindle bearing CAMROL CFH-289-4 available from McGill Manufacturing, Emerson Electric Corporation, Valparaiso, Indiana as described in the McGill Catalog No. 92. In accordance with one embodiment of the present invention, the mounting arrow 52 also includes a second cylindrical end 70 positioned next to the second mounting surface of cam follower 12b. The second arrow end 70 includes a cylindrical smooth, unthreaded outer surface 72 which passes through a beveled region 74 towards an axial end surface of arrow 76 which is generally coplanar with the annular shoulder 30c formed by the broadening section 30a, Figure 2. An internal longitudinal hole 80 - extends from the axial end surface 76 substantially coaxial with the longitudinal axis A of the mounting arrow 52 as best shown in Figures 2-3. The hole 80 is tapered internally to form the threads 82, which, for purposes of illustration only, may be 0.750-10UNC-3A threads that are 3.81 cm deep when the diameter of the arrow end 70 is 5.08 cm. (It will be understood that sizes and types of fasteners can be used, with different types of fasteners for the hole 80 and the screw 90, as described below). The mounting arrow of the cam follower 52 typically comprises hardened steel where the first arrow end 54 is heat treated to a minimum hardness of 60 Rc and the second arrow end 70 is heat treated to a hardness on the scale of 36. -44 Rc. Each of the cam followers is secured on the mounting plate or member 12 by a metal screw 90 having an elongated end portion or screw head 92 and a threaded shaft 94 threadedly received in the threaded hole 80 and a one-piece or multi-piece flat washer 100 positioned between the elongated screw head 92 and the second cam follower mounting surface 12b as best shown in Figure 2. The washer 100 is positioned on the second mounting surface of cam follower 12b (defined by shoulder 30c) and axial end surface 76 of mounting arrow 52. Metal screw 90 typically comprises a conventional hardened steel screw (Rc 38-45), designated as a screw of cap head, although the invention is not limited to any particular screw or size thereof. The detent washer 100 typically comprises a conventional steel washer having an internal diameter of 2062 cm and the external diameter of 6,202 cm, although the invention is not limited to any particular washer or size thereof. The mounting screw 90 and the mounting washer 100 described below and shown in Figure 2 are not shown in Figure 1 for clarity in the illustrated components of the rotary indexed impeller.

In the mounting of each of the cam followers 50 on the mounting plate or member 12 in accordance with a method embodiment of the invention, the screw 90 and the washer 100 for each cam follower are placed in each widening section 30a and aligned with the threaded hole 80 of the cam follower shaft 52 in the orifice section 30b. The screw 90 is then screwed into the threaded hole 80 with the washer 100 positioned below the screw head 92 around the threaded screw arrow 94 to secure the cam follower 50 in the orifice section 30b of the mounting member 12. The screw 90 is screwed to a preferred torque of approximately 282,198 m / kg, so that the cam follower 50 is suitably secured on the mounting plate or member 12. During screwing of the screw 90 into the threaded hole 80, the bending forces on the cam follower mounting arrow 52 are substantially reduced or minimized by virtue of the substantially coaxial relationship between the threaded hole 80 and the longitudinal axis of the mounting arrow 52. In this way, the follower of cam 50 is placed on the plate or mounting member 12 with little, if any, bending or bowing of its mounting arrow 52 so that the aligning substantially perpendicular to the axis A of the mounting plate 52 with respect to the cam follower mounting surfaces 12a, 12b. The improved perpendicularity of the mounting arrow 52 towards the mounting surfaces 12a, 12b transforms into the improved alignment of the cam follower relative to the cam tracks 16a, 16b of the precision cam 16. Such improved alignment reduces wear of the cam follower and cam track and prolongs their service lifetimes. In addition, the improved alignment provides a more stable cam follower (for example, one that has an improved length-to-diameter ratio of 1.5: 1 or better). After the cam followers 50 are mounted on the mounting member 12, a plastic protective cap 110 can be fitted by snapping in a manner covering each hole 30 to prevent foreign matter from entering therein. Although the invention has been described with respect to certain embodiments thereof, those skilled in the art will understand that it is not intended to be limited thereto and that changes and modifications thereto may be made within the scope of the appended claims.

Claims

1. A cam follower assembly assembly for use with a mounting member having first and second cam follower mounting surfaces and a hole between the mounting surfaces, comprising: a cam follower having a mounting arrow received in the hole and defining a longitudinal arrow shaft, said mounting arrow having a cam follower member rotatably positioned on a first arrow end close to the first cam follower mounting surface and a second arrow end next to the second cam follower mounting surface, the second end having a threaded inner bore extending from an axial arrow end surface substantially coaxial with the longitudinal axis, a screw having a threaded arrow screwed in the inner bore threaded, a washer placed between the screw and the second cam follower mounting surface; and the threaded shaft of said screw being screwed into the threaded inner bore of the mounting shaft substantially coaxially with the longitudinal axis to secure the cam follower on the mounting member with reduced bending forces on the mounting shaft to improve the alignment of the mounting arrow with respect to the mounting member.

2. The assembly of claim 1, wherein the second cam follower mounting surface is defined by an annular shoulder formed by a widening in the mounting member. The assembly of claim 1, wherein the axial shaft end surface is generally coplanar with the second cam follower mounting surface and the washer is positioned on the second cam follower mounting surface and the end surface of the cam follower. Axial arrow around the threaded shaft of the screw. The assembly of claim 1, wherein the mounting member comprises an output mounting plate of a rotary indexed impeller. 5. A method of mounting a cam follower on a mounting member having first and second cam follower mounting surfaces and a hole between the mounting surfaces, comprising: placing a mounting arrow on a cam follower in the hole of the mounting member so that the cam follower member rotatably positioned on the first end of the mounting arrow is positioned proximate the first cam follower mounting surface and a second end of the mounting arrow is placed next to the second cam follower mounting surface, and screwing a screw into a threaded inner bore of the mounting arrow extending from the second end thereof substantially coaxially with a longitudinal axis of the mounting arrow with a washer placed between the screw and the second cam follower mounting surface to secure the cam follower on the mounting member With reduced bending forces on the mounting arrow to improve the alignment of the mounting arrow with respect to the mounting member. 6. A cam follower assembly assembly for use with a mounting member having a first cam follower mounting surface, a second mounting surface, and a hole between the first and second mounting surfaces, comprising combination: a cam follower mounting arrow received in the hole and defining a longitudinal axis, the mounting arrow having a first end, a second end and a longitudinal hole internally threaded at the second end, and a channel defined by a flange outer annular having a relatively long diameter placed at the first end and an inner annular flange having a relatively small diameter, an annular end plate fixedly positioned on the inner annular flange, a plurality of low friction bearings seated in the channel, a substantially circular cam follower member rotatably positioned on the mounting shaft between the annular end plate and the outer annular flange, whereby the low friction ball bearings are enclosed sealingly in the channel by the annular end plate, the inner annular flange, the outer annular flange and the cam follower member, and means for securing the cam follower with precision of position alignment to the second follower mounting surface of the cam follower. cam. The cam follower assembly assembly of claim 6, wherein the means for securing the cam follower to the cam follower mounting surface comprises a threaded fastener for threadably engaging the longitudinal hole. The cam follower assembly assembly of claim 7, and further comprising one or more washers placed adjacent the second end of the cam follower mounting arrow and splicing the second cam follower mounting surface. SUMMARY A cam follower assembly assembly includes a mounting member, such as a rotary indexer output mounting plate, having first and second cam follower mounting surfaces and a hole between the mounting surfaces and, a follower of cam mounted on the mounting member wherein the cam follower includes a mounting arrow received in the hole of the mounting member and which has a cam follower member rotatably positioned on a first arrow end close to the first mounting surface of cam follower in a manner to be coupled by a cooperating cam rail and a second arrow end proximal to the second cam follower mounting surface. The second end of the mounting arrow includes a threaded hole extending from a second end surface substantially coaxial with the longitudinal axis of the mounting arrow. The mounting assembly further comprises a screw having an elongated head and a threaded shaft received screwed into the threaded hole of the cam follower mounting shaft and a washer positioned between the elongated head of the screw and the second mounting surface of cam follower. When the screw is screwed into the threaded hole of the cam follower mounting arrow to secure the cam follower on the mounting member, the bending forces on the mounting shaft are substantially reduced to improve perpendicular alignment in this way of the mounting arrow with respect to the cam follower mounting surfaces and therefore the cooperating cam rail, thereby improving the service life of the cam follower and the cam track.