US2912818A - Watch crowns - Google Patents

Description

Nov. 17,1959 H. G. SHAPIRO 2,912,818

WATCH paovms Filed May 27, 1957 IN V TOR.

United States Patent 2,912,818 WATCH CROWNS Harry G. Shapiro, East Orange, NJ., assignor to Joseph Waldman & Sons, Irvington, N.J., a limited partnership Application May 27, 1957, Serial No. 661,745

6 Claims. (Cl, 58-88) The invention relates to improvements in which crowns, and to the assembly of a watch crown with a winding and setting stem of a watch.

Generally, the manufacture of watches, particularly in this country, involves the purchase of watch movements and watch-crowns, and their assembly with watch cases, which are usually the individual companys own design. Due to the variation in thickness of the cases, the watch movements are received with winding and setting stems which are longer than finally necessary so that the watch stem maybe cut down to the desired length for assembly of the movement, crown and the particular case design.

. In fitting and securing the crown onto the stem of a casedmovement, the proper spacing of the crown with respect to the case has been a 'source of difiiculty and great expense. The crown must be fastened to the stern so that in winding position the crown will not engage the. case to cause resistance to rotation of the crown, and yet, the crown must not be so far spaced from the case that the assembly is unsightly or damage made possible to the unduly protruding crown.

Watch crowns in commercial use are made with an internally threaded post to enable threading the crown onto the stem.; The very nature of the assembly operation makes it difficult to ascertain exactly at what point on the stem the crown will finally be located. After threading the crown onto the cut stem, it must be tightened to provide a frictionor jam-fit to enable the stem to be rotated by the crown in a direction opposite to the direction of the thread hand, as required when setting the watch. The cutting and trimming of the stem to proper length and assembly of the crown therewith to furnish the desired spacing between crown and case has required an exactitude beyond the capabilities of even highly skilled personnel to maintain a desired minimum of defective work.

It has been proposed to overcome the problems and expense of the above-described exacting cutting and trimming of the overlong stem, and assembly of a crown therewith by. providing a machine designed to cut and trim the watch stem to enable more accurate fitting of the crown onto the stem of a given cased movement. Such machine is made with a reciprocatory carriage in which the watch with the over-long stem is supported for movement :past a motor driven abrasive wheel. Gauge meansis required in positioning the cased movement'within the carriage, and it is necessary to very closely gauge the position of the motor driven abrasive wheel in order to grind the end of the stem. While such machine has advantages over the hand operations of cutting and trimming, -a measure of skill is required to make'the necessary fine adjustments. Moreover, exact ,stemlength is difiicult to predetermine within the small 2,912,818 Patented Nov. 17, 1959 available tolerances, because of the variance in the distance the crown may move axially on the stem as it is tightened to provide the necessary frictionor jam-fit.-

It has also been proposed to provide a watch crown made of two parts designed to eliminate the close tolerances required in cutting and trimming the overlong stem to desired length. This proposal involves making the crown parts so that a cavity to receive bonding material is provided between the parts and in communication with the stem to secure the parts to the stem so that the crown parts may rotate together with the stem in either direction of rotation. This construction has introduced problems attending the use of bonding material in the very small amounts compelled by the small size of the parts. If an inadequate amount of bonding material is used, the crown parts will not be adequately secured to the stem, and it more bonding material is applied than can be accepted by the volume of the cavity, the parts will not be properly assembled. The small space available to receive the bonding material makes a small deviation from the exact suitable amount a comparatively large percentage of the total amount. The controls must be very close, it also being difficult to control the characteristics of a bonding composition within the limitations imposed by the necessity of using such very small amounts of a composition. Moreover, when heat is used to set the bonding material to a state where the bond is adequate, it is diflicult to prevent damage to the finishes on the case and crown by the immediately adjoining heating element.

The primary object of the present invention is to provide a watch crown which is constructed to enable cutting the overlong stems to proper length within a comparatively wide tolerance range, and to enable securing the crowns to the cut stems uniformly in properly spaced relationship with respect to the watch cases in a manner which is of such simplicity and devoid of close controls that little skill is required to produce uniformly suitable results. The cost of the entire operation is substantially less than existing procedures, and the percentage of defective work is minimal.

These, and other objects and advantages of the invention, will be apparent from the following detailed description taken in conjunction with the drawing, in which the figures are greatly enlarged for clarity of illustration:

Fig. 1 is a vertical cross-sectional view of a two-piece watch crown made in accordance with the invention;

Fig. 2 is a vertical cross-sectional view, with the Winding and setting stem shown in elevation and in setting position, showing the manner of removing the excess of the over-long stem after one of the crown components has been threaded onto the stem;

Fig. 3 is a view taken approximately in the plane of line 3- of Fig. 2 showing means for clamping the stem; and

Fig. 4 is a vertical, cross-sectional view showing both Watch crown components as assembled on and secured to the cut stem to enable rotation of the stem in either direction.

A watch crown made in accordance with the invention, generally, comprises a crown body A and a locking member or insert B for cooperation therewith to enable locking the crown body, and the locking member, to the usual externally threaded winding and setting stem C. The locking member is provided with a threaded bore for threading the member onto the stem. The thickness of the locking member, or its dimension in a direction parallel to the longitudinal axis of the stem, is utilized to predetermine the length'of the stem to be received within the watch crown. The upper surface of the member extending radially, or in a plane perpendicular to the longitudinal axis of the stem, provides a line of reference for the severance of the excess portion of the over-long stern which extends beyond the member after threading the member onto the stem.

The crown body A is provided with an internally threaded bore for mating engagement with the threaded stem. The crown body and locking member are form-2d or contoured so that when the crown body is threaded onto the stem and into engagement with the locking member after threading on the cut stem, the crown body may be further tightened or rotated against the resistance of the engaging forces between the parts. This is accomplished by making the internally threaded bore of the crown body of suflicient length to allow further movement of the stern therein when the crown body and the locking member are in engagement. tinued threading or tightening of the crown body onto the stem causes both the crown body and the locking member to be securely fastened to the stem for rotation therewith in either direction of rotation of the stem. By spacing the base or closed end of the bore of the crown body a sufficient distance above the end of the cut stem, the further rotation of the crown body, while resisting further travel of the locking member longitudinally along the stem, results in a distortion of the relatively thin inclined planes provided by the mating thread portions on the crown body and stem, and locking member and stem.

Thus, by simply threading the locking member onto the stern, cutting the excess off the overlong stem along a reference line provided by the locking member, threading the crown body onto the stem-until the crown body engages the locking member, and further tightening the crown body, the crown parts are firmly secured to the stern for rotation therewith in either direction, and in proper spaced relationship with respect to the watch case. The exercise of great care to cut and trim the stem is unnecessary, and the assembly of the parts requires little or no skill or close controls.

In greater detail, and referring to the drawing for a preferred embodiment of the invention, the over-long stem C of the cased movement is pulled out to setting position as shown in Fig. 2. The portion of the stem, immediately above the watch case D, is gripped in a clamp E to prevent rotation of the stem. The clamp.

also is dimensioned to provide a gauging function. The clamp has a dimension e, in a direction parallel to the longitudinal axis of the stem, which is equal to the distance it is desired the crown shall travel from winding to setting position plus the small amount of desired clearance between the crown and the case when the crown is in winding position. The clamp E may be of any suitable construction. As shown in Fig. 3, the clamp comprises a pair of arms and 10' secured to each other by a pivot pin 12. The working end of the clamp is formed with substantially semi-cylindrical recesses 14, 14' for gripping the stem C. The arms of the clamp are suitably recessed at 16 and 16' to allow for the open ing and closing movements. The clamp is oriented so that the pivot pin, if headed, as shown in Fig. 2, is on the side opposite the case D, thereby causing no interference with the gauging function when a watch case of square or rectangular outline containing the watch movement is processed. The clamp may be in the form of a surgical clamp which leaves both hands free during clamping.

As shown in Fig. 2, the locking member'B is threaded onto the over-longstem C so that the lower surface 18 of the insert engages the clamp. The locking member preferably is in the form of a substantially circular disk having a central, internally threaded bore 20. The disk The conis dimensioned so that upon assembly with the crown body, it will be received within the crown body and concealed, thereby serving as an insert therefor. A counterbore 22 of larger diameter, and of a diameter to receive the post of the crown body as will be subsequently described, is provided above the threaded bore 20 in aligned communication therewith. A radially extending shoulder 24 is located between the threaded bore and the larger counterbore. The height or thickness of the locking member or insert is made so that the upper or radial surface 26 of the insert, adjacent the open end of the counterbore, provides a line of reference for the severance of the excess portion 28 of the over-long stem C extending beyond the locking insert. In cutting off the portion 28, it is preferred to use a jewelers saw so that it will be unnecessary to smoothen the severed top end of the stem to allow subsequent threading thereon of the crown body A. It will be understood, however, that nippers may be used to do the cutting, and the cut end finished in any suitable manner. The thickness of the insert is selected so that after severance of the excess portion 28, a suitable length of stem remains for engagement with the crown body. 7

As shown in Figs. 1 and 4, the crown body A is generally cup-shaped in contour and has a dependent annular flange 30, the outer periphery 32 of which is knurled, as is common in the art, to facilitate rotation of the part when grasped between the fingers. The exposed surface is provided with the usual shell 34 of precious metal or other metal coating, generally applied by plating, to furnish a surface finish similar to the finish of the watch case. The crown body is provided with an annular recess 36 open to the bottom thereof, which is adapted to receive the locking insert therein. A post 38 having a length less than the height or depth of the recess extends downwardly from and centrally of the crown body. The post is provided with an internally threaded bore 40 adapted to matingly engage the threads on the winding and setting stem C. The post bore is sufiiciently long so that when the crown body is threaded onto the cut stem, with the lower end 42 of the post in engagement with the radial shoulder 24 to resist further movement of crown body, the crown body may be further rotated a small amount, because the stem has room to move up in the post bore. The length of the post bore, which permits continuation of the stem therein, also affords substantial latitude or tolerance in cutting the excess part from the over-long-stem. As shown in Fig. 4, the base or closed end 44- of the post bore being spaced from the cut end of the stem, designated 45, allows such continued rotation or tightening of the crown body, and results in the application of pressure between the parts at the points indicated by the arrows x, coupled with the application of pressure upon the mating thread portions of the crown body, locking insert and stem in the directions indicated by the arrows y. Since the threads are of thin section and inclined, the threaded areas of the parts are distorted, and the crown body and the locking insert are jammed against each other and securely locked to the stern for rotation therewith in either direction.

After the two crown components have thus been locked to the stem, the clamp E is removed, and the crown is returned to winding position adjacent to and properly spaced with respect to the case D.

It is believed that the advantages of a watch crown made in accordance with the invention and the assembly 1 thereof with the stem of a watch will be apparent from a line of reference for the severance of excess stemlength, this added function of the part need not beavailed of to realize many of the other advantages of the invention. The relationship between the stem and the threaded bore of the crown body is such that a comparatively wide latitude is permissible for the point of stem severance. Upon engagement of the crown body with the locking memben'there may be as little as two threads within the crown body boreto enable further tightening and locking to the stem. On the other hand, the stem may be cut at a point so that there may be as many as six or seven threads on the stem within the crown body bore without having the cut end of the stem seated against the base or closed end of the crown body bore to interfere with the further rotation of the crown body and locking of the crown to the stem. Such comparatively wide tolerance permits suitable severance of the stem even before threading the locking member thereon, and with a little practice, even gauge means may be dispensed with.

Also, while it is preferred to form the crown body and locking member so that they engage each other at an area immediately adjacent the stern, as shown, it is within the scope of the invention to form the parts so that they will engage each other near the outer periphery of the locking member, whereupon the post may be shortened, and its added function of applying pressure to the locking member omitted.

Also, while it is preferred that the crown body and locking member be formed so that after final assembly, the locking member is completely concealed within the crown body as shown, such construction is not essential for realizing a number of the advantages afforded by the invention.

These, and other changes, will be apparent from the foregoing detailed description, and such changes are contemplated within the spirit and scope of the invention as sought to be defined in the following claims.

I claim:

1. A watch crown constructed for assembly with a threaded winding and setting stern extending from a cased watch movement, said watch crown comprising a crown body and a locking insert, said crown body having a recess open to the bottom thereof and a post extending downwardly of said crown body, said post having a threaded bore adapted for threading the crown body on the threaded winding and setting stern, said insert having a threaded bore adapted for threading the insert on said stem and a counterbore of larger diameter adapted to receive said post, said insert having a thickness not substantially exceeding the depth of said recess and a diameter less than the diameter of said recess, whereby said insert may be received and substantially concealed within said recess upon engagement by said crown body, said post bore having a length adapted to allow further movement of the stern therein upon threading the crown body on the stem and into engagement with the locking insert.

2. A Watch crown constructed for assembly with a threaded winding and setting stem extending from a cased watch movement, said watch crown comprising a crown body and a locking insert, said crown body having a recess open to the bottom thereof and a threaded bore adapted for threading the crown body on the threaded winding and setting stem, said insert having a threaded bore adapted for threading the insert on said stem, said insert having a thickness not substantially exceeding the depth of said recess and a diameter less than the diameter of said recess, whereby said insert may be received and substantially concealed within said recess upon engagement of the insert by said crown body, the bore of said crown body having a length adapted to allow further movement of the stem therein when the crown body is threaded onto the stem and into engagement with the locking insert.

3. A watch crown constructed for assembly with a threaded winding and setting stem extending from a cased watch movement, said watch crown comprising a crown body and a locking insert, said crown body having a recess open to the bottom thereof and a post having a length less than the depth of said recess, said post having a threaded bore adapted for threading the crown body on the threaded winding and setting stem, said insert having a threaded bore adapted for threading the insert on said stern and a counterbore of larger diameter adapted to receive said post, a radial shoulder being provided between-the insert bore and counterbore, said insert having a thickness not substantially exceeding the depth of said recess and a diameter less than the diameter of said recess, the upper surface of the insert, adjacent the open end of said counterbore, being adapted to provide a line of reference for the severance of the portion of an over-long stem extending beyond the insert when threaded on the stem, said insert being adapted to be received and substantially concealed within said recess upon engagement of said post with said radial shoulder, said post bore having a length adapted to allow further movement of the stem therein when the crown body is threaded onto the stem and the end of the post engages said radial shoulder.

4. In a watch, the combination of a threaded winding and setting stem and a watch crown, said watch crown comprising a crown body and a locking member therefor, said locking member having a threaded bore threading the locking member on said stem, the end of the stem being located above the area of threaded engagement of the locking member and stem, said crown body having a recess open to the bottom thereof and a post having a threaded bore threading the crown body on said stem, said post having a length less than the depth of said recess, said crown body bore having a length sufficient to allow further rotation of the crown body on the stem upon engagement of the post with the locking member, whereby the crown body in tightened engagement against the locking member secures the crown body and the locking member to the stem for its rotation in either direction by the crown body.

5. In a watch, the combination of a threaded winding and setting stem and a watch crown, said watch crown comprising a crown body and a locking insert, said locking insert having a threaded bore threading the insert on said stem, the end of the stem being located above the area of threaded engagement of the insert and stem, said crown body having a recess open to the bottom thereof and a threaded bore threading the crown body on said stem, said crown body bore having a length sufficient to allow further rotation of the crown body on the stem upon engagement of the crown body with the insert, said inesrt having a thickness not substantially exceeding the depth of said recess, whereby the crown body in tightened engagement against the locking insert secures the crown body and the insert to the stem for its rotation in either direction by the crown body, with the insert received and substantially concealed within the recess.

6 In a watch, the combination of a winding and setting stem and a watch crown, said watch crown comprising a crown body and a locking insert, said insert having a threaded bore threading the insert on said stem and a counterbore of larger diameter, a radial shoulder being provided between said insert bore and counterbore, the radial surface of the insert adjacent the open end of said counterbore providing a line of reference for the severance of the portion of an over-long stem extending beyond the insert, whereby the end of the stem is located at least at the level of said radial surface, said crown body having a recess open to the bottom thereof receiving said insert therein, a post having a length less than the depth of said recess extending downwardly of the crown body received within said counterbore and in engagement with said radial shoulder, said post having a threaded bore threading the crown body '7 8 on said stem, saidpost bore having a length sufiicient References Cited in the file of this patent toallow further rotation of the crown body on the V stern'upon engagement of said post and radial shoulder, U N D- f E A 7 said insert having a thickness not substantially exceeding 5 25 Dllebel? 92 the depth of said recess, whereby the crown body in 5 8 9 -v s P 20, 8 tightened engagement against the insert secures the crown 2,772,535 s fi'im Dec. 4, 1956 body and insert to the stem for its rotation in either direction by the crown body, with the insert received FOREIGN PATENTS and substantially concealed within the recess. 7 603,971 Great Britain June 25, 1948

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