Rocker Box Assemblies

Abstract

A rocker box assembly for attachment to the bottom of a chair to form a platform rocker or the like. The rocker box has swivel connection with the floor legs so that the user of the chair may not only rock but also swing about the legs. The improvement comprises an assembly formed mostly of steel stampings to facilitate quantity production. The interengaging rocker components are rigidly secured to superposed steel plates, and side plates are provided to insure proper alignment of the rocker components, and to prevent undesirable matter from being inserted between the rocker surfaces. A novel coil spring assembly maintains the rocker components in cooperating relationship and safety means are provided to insure against bodily harm in the event of failure of the coil spring assembly.

Description

BACKGROUND AND SUMMARY

Rocker supports for chairs are well known in the prior art, and in more recent years, such supports have been formed of stamped components. However, such prior art rocker supports have had some inherent disadvantages from the standpoints of production, noise of operation, and safety, and my invention is intended to overcome the same.

Briefly, my improved rocker box assembly comprises two spaced, superposed support plates which are substantially flat and thus readily formed in a blanking operation. Pairs of cooperating rocker members are carried by the plates in position therebetween. Side plates are rigidly secured to one of the two spaced plates and act as guards to prevent things from getting between the cooperating rockers members. This is also a safety feature to prevent children or adults from putting their fingers between the rocker members. The side plates also prevent lateral movement between cooperating rocker members and thereby hold them in proper tracking relation. Plastic buttons are interposed between the rocker members and the side plates to decrease friction and noise.

A plurality of coil springs are disposed between the superimposed plates to hold the rocker members in engagement and urge the same to central position, and safety means is disposed between a rocker member and side plate to prevent separation of parts in the event one or more of the springs should break.

DESCRIPTION OF THE DRAWINGS

In the drawings accompanying this specification and forming a part of this application, there is shown, for purpose of illustration, an embodiment which my invention may assume, and in these drawings:

FIG. 1 is a top plan view of my improved rocker box assembly,

FIG. 2 is a broken, side elevational view corresponding to the line 2--2 of FIG. 1, but drawn to a larger scale, a portion of the chair being shown in phantom lines,

FIG. 3 is an enlarged sectional view corresponding to the line 3--3 of FIG. 1,

FIG. 4 is a sectional view corresponding to the line 4--4 of FIG. 2,

FIG. 5 is a fragmentary sectional view showing a slightly different transverse configuration of the cooperating rocker members,

FIG. 6 is a sectional view corresponding to the line 6--6 of FIG. 4,

FIG. 7 is an enlarged, fragmentary sectional view corresponding to the line 7--7 of FIG. 6,

FIG. 8 is a detail view illustrating a method of installing a coil spring,

FIG. 9 is a fragmentary, enlarged plan view showing a coil spring mounted on a support plate, and

FIG. 10 is a fragmentary perspective view showing the spring anchoring portion of the support plate.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The improved rocker box assembly comprises a pair of rectangular superposed steel support plates 15 and 16 which are largely flat and therefore readily formed in a blanking operation. The top plate 15 (see FIG. 1) is formed with openings 17 at its corners to pass screws or bolts for securement to the base of a chair C, the latter being fragmentarily shown in FIG. 2.

The lower plate 16 has a swivel connection with the legs L of the chair and this connection may be of any suitable form since its details are not a part of this invention. For illustration purposes, the bottom plate may have a central opening margined by a tubular boss 18, as seeen in FIGS. 3 and 4, to closely receive a swivel pin 19. A cupped leg support plate 20 underlies the lower plate 16 and has a corresponding tubular boss 21 to receive the swivel pin. Plastic discs 22, 23 are secured to the facing surfaces of respective plates 16 and 20 and provide a bearing surface. The pin 19 may be held in position by cross-pins 24 which bear against washers 25. The legs L are secured to the plate 20 and may have rollers or gliders 26 at their floor engaging ends.

Pairs of cooperating rocker members are disposed between the facing surfaces of the top and bottom support plates. Each pair includes an upper member 30 and a lower member 31. Preferably, all rocker members are of the same construction and therefore may be made with the same blanking and forming dies, in matching pairs.

In transverse section, as seen in FIGS. 4 and 7, each rocker member has a central web portion 32, a leg portion 33 which is flat both crosswise and lengthwise and an opposed leg portion 34 which is flat crosswise, but arcuate lengthwise as seen in FIG. 6. A further leg portion may be turned at right angles from the leg portion 34 for strength purposes, such further leg portion being spaced from but parallel to the corresponding web portion 32.

The leg portions 33 of the upper rocker members 30 are secured to the upper support plate 15, such as by welding shown at 35. The leg portions 33 of the lower rocker members 31 are similarly secured to the lower support plate 16. As seen in FIG. 6, the lengthwise arcuate formation of the leg portions 34, 34 form interengaging rocker surfaces, so that the chair may be rocked by its occupant. The swivelpin 19 and bearing surfaces 22, 23 permit the chair to be swiveled by its occupant.

As seen in FIG. 5, the upper and lower rocker members 30, 31 may be slightly modified by making the leg portions 34a, 34a of interfitting concave-convex formation to further insure tracking of the cooperating surfaces.

In order to prevent insertion of objects between the interengaging rocker surfaces and to maintain the rocker members in tracking relation, side plates 38 are disposed exteriorly of and in juxtaposition with respect to the web portions 33 of the cooperating rocker members, as seen in FIG. 4. This feature prevents damage to the interengaging surfaces and precludes objectional stresses from being applied to the rocker box components which otherwise might result if it were possible to insert a hardened object between the rocker surfaces. This is also a safety feature to prevent fingers and toes from being inserted between the interengaging rocker surfaces. Each side plate may have the configuration shown in FIG. 2 and may depend from and be welded to the upper support plate 15, as seen at 39 in FIG. 4.

A plurality of coil springs 40 are connected between the upper and lower support plates 15 and 16 to hold the rocker surfaces in interengagement and to urge such surfaces to the central position shown in FIG. 6. All coil springs may be the same and, as seen in FIG. 1, one coil spring may be disposed on the centerline 41 at the front of the support plates, and a pair of springs may be disposed on opposite sides of such centerline at the rear of the plates. This construction is preferable because more weight is imposed on the two rear springs when the chair is rocked backward.

My invention includes novel construction whereby each coil spring may be quickly, easily, and positively assembled with the top and bottom support plates. As best seen in FIGS. 9 and 10, each support plate is formed with a spring anchorage portion at the place where the spring is to be connected to the plate. Such anchorage comprises a semi-circular recess 42 which is formed inwardly of the plate surface by a stamping operation. The recess provides a center anchor projection 43 which is also semi-circular in plan, as seen in FIG. 9. The front surface of the projection 44, which is at the straight edge of the support plate, is inclined toward the outer surface of the plate and forms a cam surface for a purpose to be explained.

Each of the coil springs has closely disposed convolutions at opposite end portions, as shown at 45 in FIG. 8, and the adjoining convolutions at the central portion of the spring are spaced further apart, as shown at 46. Normally, the length of each spring is less than the space between upper and lower support plates 15 and 16. FIG. 8 illustrates the method of assembling a coil spring with the upper and lower support plates. The jaws 50 of a plier-like tool 51 are disposed between adjoining central convolutions of the spring and the spring is expanded lengthwise until the convolutions at opposite ends of the spring are aligned with upper and lower plates at the recesses 42. A force is then applied as shown by the arrows 52, either by a pressing action or by tapping with a hammer. The applied force causes the end convolution to ride over the cam surface 44 and snap into the recess 42 and thereafter the anchor projection 43 holds the spring against disassembly.

As before pointed out, the coil springs hold the rocker surfaces in engagement and the springs at the front and rear of the rocker box assembly are alternately compressed and stretched during rocking action of the chair. Sometimes a coil spring breaks, either because of a defect or wear, and in prior construction such breakage could cause a sudden, unexpected movement of the chair and might cause the chair's occupant to be thrown from the chair by reason of separation of the cooperating rocker members.

My invention provides an additional safety feature in that breakage of a coil spring will not result in any material separation of the cooperating rocker members. As best seen in FIGS. 4 and 6, a retaining member 54 is disposed at the center of rocking action and this member comprises a headed stud having its head 55 welded to the outside surface of the adjoining side plate 38. The shank 55.1 of the stud loosely passes through an oversized hole in the web 32 of the lower rocker member. Therefore, the stud does not interfere with rocking action and yet will prevent any material separation of the rocker members in the event a coil spring should break or become unfastened.

In order that the side plates 38 may be disposed close to the webs 32 of the rocker members 30, 31, and yet not interfere with operation thereof or cause noise during operation, bearings are disposed therebetween. With reference to FIGS. 2, 6 and 7, each of the bearings comprise a headed stud 56 formed of a suitable plastic material, such as nylon. The studs are disposed on opposite sides of the retaining member 54 and the shank 57 of each is threaded through an opening in a side plate 38. The head of the studs are disposed between the inner surface of a side plate 38 and the facing surface of the web 32 of a lower rocker member 31 and provide bearing buttons for sliding engagement with the webs.

Claims

I claim:

1. A rocker box assembly for disposition between the seat and base of a chair and the like, comprising:

a pair of generally flat metal support plates, superposed in spaced relation, the upper support plate being adapted for connection to the chair seat and the lower plate being adapted for connection to the chair base,

two laterally spaced rocker means between said upper and lower plates, each rocker means comprising a first rocker member secured to and depending from said upper support plate and having a lower longitudinally convex rocker surface, and a second rocker member secured to and extending upwardly from said lower support plate and having an upper longitudinally convex surface engaging and cooperable with said lower convex surface, said lower convex surface being adapted to rock over said upper convex surface,

and a side guard disposed outwardly of each of said first and second rocker members, each side guard being connected to and depending from said upper support plate and extending short of said lower support plate so as not to interfere with rocking movement, each side guard overlapping substantially the full length of the engaging parts of said lower and upper convex surfaces to prevent disposition of foreign matter between the same in any normal rocking position.

2. The construction according to claim 1 wherein each of said upper and lower rocker members is formed of metal and is generally of channel shape in transverse section, including a web and legs extending at right angles from opposite ends of said web, one leg being rectilinear in longitudinal section and secured to its respective support plate and the other leg being arcuate in longitudinal section to provide the convex rocker surface.

3. The construction according to claim 2 wherein the rocker members of each rocker means have their webs in vertical alignment, each side guard comprising a flat metal rigidly connected to and depending from said upper support plate in closely spaced relation with respect to the aligned webs.

4. The construction according to claim 3 and further including slide bearing means between facing surfaces of each side guard plate and the web of a related lower rocker member.

5. The construction according to claim 4 wherein each slide bearing means comprises a headed plastic stud, the shank of said stud being fixed in a hole in said side guard plate and the head of said stud having sliding engagement with the web surface of a related lower rocker member.

6. A rocker box assembly for disposition between the seat and base of a chair and the like, comprising:

a pair of generally flat metal support plates, superposed in spaced relation, the upper support plate being adapted for connection to the chair seat and the lower plate being adapted for connection to the chair base,

two laterally spaced rocker means between said upper and lower plates, each rocker means comprising a first rocker member secured to and depending from said upper support plate and having a lower longitudinally convex rocker surface, and a second rocker member secured to and extending upwardly from said lower support plate and having an upper longitudinally convex surface engaging and cooperable with said lower convex surface, said lower convex surface being adapted to rock over said upper convex surface,

a plurality of coil springs between said upper and lower support plates, providing means for holding said plates in assembled relation and for holding said convex surfaces in rocking engagement,

and means operative in the event of spring failure for holding said support plates and said convex surfaces against material separation.

7. The construction according to claim 6 wherein each of said upper and lower rocker members is formed of metal and is generally of channel shape in transverse section, including a web and legs extending at right angles from opposite ends of said web, one leg being rectilinear in longitudinal section and secured to its respective support plate and the other leg being arcuate in longitudinal section to provide the convex rocker surface, the rocker members of each rocker means having their webs in vertical alignment,

a side guard disposed outwardly of each of said first and second rocker members, each side guard comprising a flat plate rigidly connected to and depending from said upper support plate in closely spaced relation with respective aligned webs,

the last named means in claim 20 comprising a stud secured to a side guard plate to coincide with a central position of the cooperating lower and upper convex surfaces, said stud having its shank fitting into an oversized hole in the web of the related lower rocker member, whereby free rocking of said lower convex surface over said upper convex surface is permitted, but whereby the stud shank engages a margin of the hole in the web of the related rocker member in the event of spring failure.

8. A rocker box assembly for disposition between the seat and base of a chair and the like, comprising:

a pair of support plates, superposed in spaced relation, the upper support plate being adapted for connection to the chair seat and the lower support plate being adapted for connection to the chair base,

rocker means between said plates so that the latter may rock relative to each other,

and coil springs connected between said plates to yieldably oppose relative rocking movement of said support plates, the spring connection comprising a semi-circular recess in a marginal portion of a plate and a semicircular projection concentric within said recess and tapering from a larger size at the bottom of said recess to a smaller size at the top, said projection having a cam face at the marginal portion of said plate and being engageable with an end convolution of a coil and operable, upon application of lateral force to said end convolution to spring it apart from an adjoining convolution sufficiently to permit said end convolution to ride over said projection and snap into said recess.