US2171361A - Knob structure - Google Patents

Description

J. A. GITS ET AL KNOB STRUCTURE Filed July 29, 1937 Patented Aug. 29, 1939 UNITED STATES PATENT-OFFICE KNOB STRUCTURE Joseph A. Gits and Jules P. Gits, Chicago, ill. 1 Application July 29, 1937, Serial No. 156,288

4 Glaims.

This invention relates to knob construction and more particularly to a molded dial knob adapted to be mounted upon a spindle or shaft which it actuates.

Although apparently simple in construction, dial knobs of molded construction have heretofore presented-a difficult problem in their manufacture. Knobs of this type must be provided with securing means that will secure them to the shaft upon which they are carried so that they may turn the shaft when rotated and not be displaceable except when desired. Uneven shrinkage has been exceedingly troublesome in the molding operation of devices of this type, and has caused the adoption of expensive forms of securing means, some of which areeii'ective and others of which do little to overcome the uneven shrinkage or provide a proper and effective connection between the knob and shaft.

It is an object of the invention,therefore, to provide a simple and inexpensive form of dial knob that is so designed as to admit of a uniform molding operation and provide thereby an integral unit having parts of substantially uniform thicknesses whereby to overcome uneven shrinkage, and further to provide as a part of said integral unit an inexpensive but very efiective securing means between the knob structure and the shaft so that the knob may rotate said shaft and be axially displaceable only when desired.

A further object of the invention is to provide a dial knob of the type described having the characteristic mentioned in which a minimum of material may be used although providing a structure of exceptionally great strength.

A still further object of the invention is to provide this type of knob in which a simple but effective form of securing means may be provided between the knob and the spindle to which it is attached.

To this end provision is made in the form of securing means that may be embodied as part of the knob and also as part of the structure of the spindle whereby added parts, such as metallic inserts, set screws, spring inserts, or the like, may be eliminated. It is found that with a simple form of securing means the problem of molding the knob body is simplified and a structure may be provided that more readily eliminates the problem of uneven shrinkage in the molding operation and provide a more. efllcient, simple and inexpensive structure.

In ordertc apprise those skilled in the art how to construct and practice the invention, I

shall now describe several preferred embodiments in connection with the accompanying drawing which forms a part hereof.

In the drawing:

Figure 1 is a perspective view of a knob em- 15 bodying'the invention, which knob is shown as mounted upon a shaft or spindle;

Fig. 2 is a vertical section of this knob illustrating the securing means holding the knob to the spindle;

Fig. 3 is a view similar to Fig. 2 but with the knob and spindle separated;

Fig. 4 is a rear view of the knob;

Fig. 5 is a transverse section ofthe knob taken along line 5-5 of Fig. 3; 1

Fig. 6 is a view similar to Fig. 3 but illustrating a slightly modified form of knob embodying the invention;

Fig. '1 is a view similar to Figs. 3 and 6, but illustrating another alternative embodiment of the invention;

Fig. 8 is a perspective view of the knob looking toward the rear face thereof, and

Fig.- 9 is an end view of the form of knob shown in Fig. 7-

The dial knob I illustrated in Figs. 1, 2 and 3 comprises essentially a uniformly molded integral unit composed of two parts, to-wit, a head 2 and a shank 3. Head 2 is preferably designed to be of substantial uniform thickness throughout, as will be noted in Fig. 2, while shank 3 is preferably formed of a plurality of Walls likewise of substantial uniform thickness. These walls are preferably made by providing cavities 4 in shank 3 during the molding operation. In the form illustrated, these-walls are preferably arranged as concentric shell or sleeve-like. members I and 6 that are joined by inter-connecting spacing ribs I. A

It will be noted therefore that theintegral 4o body is uniformly molded into a structure having its parts of relatively uniform thicknesses so that any tendency for uneven shrinkage in the molding operation is eliminated. Inner concentric sleeve-like member 5 is furnished with an opening 8 adapted to receive the end of a spindle 9 to which knobs of this type are adapted to be carried to rotate or to act as a handle for moving this spindle from one position to another. We preferably provide a simple securing means between knob I and spindle! in the form of corresponding irregularities along the surfaces of opening 8 and spindle i. such irregularities bein for example, projections, ribs or beads engageable in corresponding grooves whereby these 5 parts are secured together against relative rotation and accidental axial displacement.

As illustrated in the embodiment shown in Figs. 2 and 3, the inner wall of sleeve 5 forming central opening 8 may be provided with an annular head or projection l0 arranged to slip into an annular groove I l in shaft 9. By providing an exceptional close fit between the shaft 9 and the wall of opening 8, we are able to secure a snug fit between these parts. However; we preferably provide knob I of a material, such as cellulose acetate, which will yield slightly within certain limits when put under pressure. By limiting the thickness of concentric members 5 and 6 which may be advantageously accomplished by virtue of the cavity formation provided by cavities 4 between these parts, the inner concentric member 5 may be made to yield slightly when bead I9 is forced over the end l2 of shaft 9 until this bead l9 dropsinto groove II. To secure a snug fit in an axial direction between knob l and shaft 9, we preferably make shaft groove H slightly larger than bead l9. When bead I llis slipped over the forward end or head l2 of shaft 9, it will drop into'groove l I, but will rest against the forward portion I3 of the same, as illustrated in Fig. 2, to effect a cam-like action tending to pull and hold knob l upon the end of shaft 9 It will be apparent that this cam action between bead l0 and its larger groove II will advantageously take up any looseness between the parts due to slight variations in manufacturing clearances.

A specific form of securing means preventing relative rotation between knob l and shaft 9 may include a projection or rib I l integrally formed in the molding operation upon the inside face of head 2, which projection or rib I 4 will cooperate or engage in a similarly shaped groove l5 formed in the tip [2 of shaft 9. It will be apparent that.

when rib or projection l4 aligns with groove l5, the spring action of bead l0 tending to return to its normal position will snap into position in groove H and hub against the forward edge l3 so as to hold knob l tightly upon the shaft and prevent accidental axial displacement but permit ready removal of this knob, if a pulling force sufficient to force bead l0 out of groove H and over end l2 of shaft 9 is employed.

If so desired, rib M on the inside of head 2 may be eliminated and a groove l8 provided in lieu thereof, thereby permitting the use of an equivalent rib or projection l9 on shaft 9, as illustrated in Fig. 6, whereby, when knob l is slipped upon the end of shaft 9, rib or projection l9 on this shaft will enter this groove l8 formed in head 2.

Another form of connection between knob l and shaft 9 is illustrated in Fig. 7. A U member 20 may be molded in head 2 so as to project forwardly from its inside face whereby to engage in a corresponding recess 2| in the end face of shaft 9. Obviously, different forms of securing means may be provided, as illustrated herein, either to prevent axial displacement of knob I from shaft 9, or to prevent relative rotation between these parts.

As previously mentioned, knob i may be molded of any suitable material, such as cellulose acetate, and formed as an integral body of uniformly molded parts to prevent uneven shrinkage, which heretofore has caused considerable trouble and expense. Usually a dialknob is provided with a large forward face that may be either fiat or curved. If uneven shrinkage occurs, it will usually show itself across this face and detract from the appearance of the knob. We find that to secure uniform shrinkage at head 2, it is preferable if not quite essential to provide the walls or parts forming the rearwardly projecting shank 3 likewise of substantially uniform thickness. foregoing description that we are able to provide shank 3 of walls or parts of substantially uniform thicknesses by virtue of the cavity formation provided by cavities 4 and the centrally located opening 8 in member 5 that receives shaft 9. Moreover, it will be-apparent that the securing means employed herein between knob I and shaft 9 may be integrally formed without affecting in any way the uniform molding of knob i into parts of substantially uniform thicknesses. As previously explained, the material, out of which knob I may be molded, may be suificiently springy in character to yield slightly under pressure. In the event it is desirable to adopt knob l to a shaft having a slightly smaller diameter than originally contemplated for the size of knob made, it is apparent that the variation may be easily compensated for by making bead l0 slightly larger, which will eliminate the necessity of changing the entire mold to increase the size of the knob. Likewise, bead It may be made smaller if shaft 9 should be slightly larger than originally contemplated for the size of opening 8 provided, and the inner sleeve 5 may then be slitted, as illustrated at 2 2, so that it may readily slip upon the end of the shaft to allow this bead ID to enter groove ll.

Without further elaboration, the foregoing will so fully explain the gist of our invention that others may, by applying current knowledge, readily adopt the same for use under varying conditions of service without eliminating certain features, which may properly be said to constitute the essential items of novelty involved, which items are intended to be defined and secured to us by the following claims.

We claim:

1. A knob of the type .described adapted to be secured to a shaft to rotate the same comprising a molded body having an opening therein for said shaft, a bead on said body within said opening adapted to cooperate with a groove formed in said shaft to prevent axial displacement of said body from said shaft, the rear wall of said opening being engaged by the end of said shaft to limit its axial movement, said bead being relatively smaller than said groove and positioned relative to said rear wall to engage the forward portion of the wall of said groo've whereby to tightly hold said body upon said shaft by a snap engagement.

- 2. A knob of the type described adapted to be secured to a shaft to rotate the same comprising a molded body having an opening therein for said shaft, an annular bead on said body within said opening adapted to cooperate with an annular groove formed in said shaft to prevent axial displacement of said body from said shaft, means engageable by said shaft to limit its axial movement in said opening, said head being relatively smaller than said groove and positioned relative thereto to engage the forward portion of the wall of said groove whereby to tightly hold said body upon said shaft, and means between said body and said shaft to lock said body against relative rotation upon said shaft.

3. A knob of the type described adapted to be attached to a spindle comprising a molded body It will be apparent from the I of plastic material'having a head and a shank, said shank being provided with a plurality of recesses forming a plurality of yieldable walls, there being a substantially centrally located spindle opening of approximately the same diameter as said spindle, and a bead formed on one of said walls and lying within said opening adapted to cooperate with a groove in said spindle, said wall yielding to the pressure upon said head upon the insertion of said spindle in said opening, said wall returning to its original position when said bead drops into said spindle groove.

4. The combination with a molded body of plastic material adapted to be mounted upon a spindle, there being an opening in said body to receive said spindle and means to limit the distance said body'may axially move relative to said spindle, of means for holding said body upon said spindle, said means being carried by said parts and comprising a bead and a groove, said bead being smaller than said groove and positioned relative to said movement limiting means to engage the forward portion of the wall of said groove whereby to hold said body tightly upon said spindle by a snap engagement.

JOSEPH A. GITS.

JULES P. GITS.

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