Abstract:
A dog-bone shaped bumper for a telescoping way cover extends on both sides of the rear flange of the cover and defines spaces which close upon flexing of forked ends of the bumper between the rear flange and the next adjacent cover section to reduce the impact between sections when expanding and retracting the cover.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Not applicable. 
     STATEMENT CONCERNING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     FIELD OF THE INVENTION 
     This invention relates to telescoping covers and in particular to a bumper of a telescoping cover which absorbs the impact between adjacent cover sections upon extension and retraction of the cover. 
     BACKGROUND OF THE INVENTION 
     Telescoping covers, such as the telescoping machine tool way covers shown in FIGS. 1-3, are typically made of a number of sheet metal sections which are telescoped together. The sections have end walls or flanges that catch on one another so that when one end of the cover is pulled away from the opposite end of the cover, the cover expands by one of the end walls or flanges of one of the sections abutting the end wall or flange of the next adjacent section. Similarly, when retracting, the end walls or flanges of the way sections abut the end walls or flanges of the adjacent way sections until the way cover is totally collapsed. 
     Some sort of bumpers have normally been used to dampen the impact as one way cover section bumps into another. These bumpers have typically been elastomeric pads which are placed between the abutting walls of adjacent way cover sections. 
     While they have been somewhat effective, the spring rate of them has generally been either too soft or too stiff. Also, as they have typically been molded elastomeric compound, they have been prone to deterioration from repetitive use and attack by the oils and chemicals. Others have been simply adhered to the walls of the sections and have been prone to falling off which can jam the way cover since if it falls off on one side but not the other, it can become skewed, requiring expensive downtime of the machine tool. 
     SUMMARY OF THE INVENTION 
     The present invention provides a bumper with a spring rate and dampening capability adapted for a way cover which is dog-bone shaped and made of an elastomeric material which is held on a flange of a way cover section so that it straddles the flange, extending from each side of the flange. The bumper is dog-bone shaped to provide a combination of flexing and compression to yield a soft start from flexing of the ends of the bumper and provide faster acceleration of the cover sections beyond the flexing limit of the bumper. 
     Two or more such bumpers, each of a uniform thickness, are preferably provided on each flange. 
     In addition, since the bumper is made of an elastomeric material, it can be made with mounting holes which can be expanded over mounting projections of the flange so as to hold the bumper mechanically straddling the flange. Such a bumper provides a progressive spring rate to dampen the acceleration forces that occur when one section bumps into another and which is durable, easily assembled and largely trouble-free in use. 
     The foregoing and other objects and advantages of the invention will appear in the detailed description which follows. In the description, reference is made to the accompanying drawings which illustrate a preferred embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a telescoping way cover of the type in which bumpers of the invention are used; 
     FIG. 2 is a bottom perspective view of the cover of FIG. 1; 
     FIG. 3 is a perspective view of the cover of FIG. 1 from the opposite end; FIG  4  is a perspective view of two telescoping middle sections of a cover like that shown in FIGS. 1-3, with one of the bumpers of the invention shown on the left set of mounting projections; 
     FIG. 5 is a detail view of area B of FIG. 4; 
     FIG. 6 is an end view of the cover sections of FIG. 4; 
     FIG. 7 is a sectional view from the plane of the line  7 — 7  of FIG. 6; 
     FIG. 8 is a perspective view of a cover bumper of the invention; 
     FIG. 9 is a top plan view of the bumper of FIG. 8; and 
     FIG. 10 is a side plan view of the bumper of FIGS.  8  and  9 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1-3 illustrate a known construction of a telescoping way cover  10  of the type which could incorporate bumpers and bumper retaining structures of the invention. Such a way cover is made up of a number of sections  12  which are telescoped relative to one another. 
     Typically, one end of the cover  10  is fixed to the stationary frame of a machine tool and the other end is affixed to the moving table of the machine tool so that the cover  10  can telescope extended over the ways of the machine tool to cover them, or telescope retracted. Wipers  16  may be provided at the outer exposed edge of each of the sections  12  to wipe over the top of the adjacent section when the cover is closed to keep it clean of any debris which may have fallen down from the machining head. 
     FIGS. 4-6 illustrate two telescoping sections for a telescoping way cover like that of FIGS. 1-3, although the way cover sections in FIGS. 4-6 are flat top whereas the way cover of FIGS. 1-3 is peaked. The operation of the way cover of FIGS. 4-6 is, however, generally the same. In addition, the way cover sections of FIGS. 4-6 are modified to incorporate bumpers of the invention. Referring to FIG. 4, a bumper  20  of the invention is flat with a generally dog bone-shaped profile, being forked at each end and of reduced width in the middle. Referring to FIGS. 8-10, the bumper  20  is preferably cut from elastomeric sheet material. A suitable material is high-grade buna elastomeric sheet material (e.g., Shore A 45-55 hardness, ¼″ thick for larger, heavier covers and {fraction (3/16)}″ thick for smaller covers). Sheet material is more dense and homogeneous than molded material, and is more resistant to fatigue and chemicals and oils in the machining environment. 
     The bumper  20  has forked ends  22  with a V-shaped depression  24  between the ends. The ends  22  at each end of the bumper  20  are spaced apart, and the central section  26  of the bumper  20  is reduced in width from the end sections. 
     Three elongated holes  28  are aligned along an axis  30  (FIG. 9) of the bumper  20  and are sized so that when they are slightly stretched out, they fit over three tabs  32  which are generally trapezoidally-shaped, tapering toward the bottom, and are cut into the upper edge of flange  38  of each section  12 . 
     The shape of the bumper  20 , and particularly the V-shaped notches  24 , enables it to fit closely between the ends  42  which are cut in the flange  38 , with the two ends  22  which are on one side of axis  30  extending on one side of the flange  38 , and the other two ends  22  on the other side of the axis  30  extending on the other side of the flange  38 . The V-shaped notch  24  also gives room for the two ends  22  on each side of the flange  38  to flex toward the flange, as does the narrowed down width of the bumper  20  in the central section  26 , so that the ends flex to initiate a “soft start” to the motion of a stationary section being pushed or pulled by an adjacent moving cover section. Rapid acceleration or higher forces between the two sections result in compression of the elastomeric material of the bumper  20  when the limit of flexing of the ends  22  is reached. The thickness of the bumper  20  should be sufficient to resist torsional forces which tend to roll the ends out of their normal, unstressed plane. 
     On the front side of the flange  38 , the sides  46  adjacent to the ends  22  contact the rear side of the wiper retainer  48  when the two sections  12  are expanded relative to one another and the ends  22  are compressed against the front side of the flange  38  thereby. When the sections  12  are retracted relative to one another, the two ends  22  on the rear side of the flange  38  contact the flange  38  below the top wall of the next larger section  12  and are compressed against the flange  38  of the section on which the bumper is mounted. It is noted that in FIGS. 4 and 6, only one bumper  20  is shown assembled to the section  12 , although bumpers  20  would be provided on both sides of the section  12  attached to both sets of tabs  32  which are provided in the section  12 . The flanges  38  and the wiper retainer  48  are welded to the sections  12 , which are made of sheet steel. 
     Preferred embodiments of the invention have been described in considerable detail. Many modifications and variations to the embodiments described will be apparent to those skilled in the art. Therefore, the invention should not be limited to the embodiments described but should be defined by the claims which follow.