HK1037021B - Improved puzzle-lock compression ring - Google Patents

Description

Improved tangram type locking compression ring and its manufacturing method

This application is a divisional application of chinese patent application 97110742.4 (application date: 1997, 4/16; title: modified tangram type locked compression ring).

Technical Field

The invention relates to a compression ring with a mechanical connection of the so-called jigsaw puzzle lock type, which can be contracted onto an object to be fixed.

Background

Compression rings with so-called heptagonal plate-type locking connections are disclosed in the inventor's U.S. patents 5,001,816 and 5,185,908. These prior art heptagonally interlocking compression rings have proven to be quite successful. However, they sometimes come loose during their shipment to the user. In addition, there is a continuing need for improvements in the retention capabilities of such compression rings.

Disclosure of Invention

It is therefore an object of the present invention to provide a tangram-type locked compression ring which eliminates the aforementioned drawbacks in a simple and cost-effective manner.

It is a further object of the present invention to provide a compression ring of the above type having improved retention of the heptaplate type closure connection.

It is yet another object of the present invention to provide a tangram-type closure compression ring that is effective in preventing loosening during shipping. Although the foregoing patents of the present inventor refer to spot welding, laser welding and material transfer using a central punch, these prior art patents do not refer to any specific details particularly regarding swaging operations.

To achieve the above object, according to one aspect of the present invention, there is provided a compression ring having a mechanical connection in the form of complementary female and male portions at respective ends of the compression ring, the male portion having a tongue-like extension with an enlarged head adapted to fit into a complementary shaped recess in the female portion, wherein the head comprises: a transverse abutment surface extending substantially perpendicular to the substantially longitudinally extending abutment surface of the tongue-like extension; lateral abutment surfaces extending substantially in the longitudinal direction of the compression ring and extending in a substantially perpendicular manner to said transverse abutment surfaces; and a transverse end abutment surface, wherein said lateral abutment surface extends through the arcuate configuration to said end abutment surface.

In accordance with another aspect of the present invention, there is provided a method of forming a compression ring from a flat strip having a mechanical connection at its male and female ends, comprising the steps of: stamping a flat blank having male and female ends to form complementary portions of said mechanical connection, said mechanical connection having a tongue-like extension with an enlarged head on its male portion and a complementary recess on its female portion, wherein said head comprises: a transverse abutment surface extending substantially perpendicular to the substantially longitudinally extending abutment surface of the tongue-like extension; lateral abutment surfaces extending substantially in the longitudinal direction of the compression ring and extending in a substantially perpendicular manner to said transverse abutment surfaces; and a transverse end abutment surface, characterized by the further step of providing a transition portion in the form of a circular arc from said lateral abutment surface to said end abutment surface.

According to one embodiment of the invention, the performance of a tangram-type closure connection is improved by providing additional material in critical areas that have been subject to tearing or pulling (due to stresses caused by circumferential forces in the ring) without significantly reducing the length of the abutment surfaces for absorbing forces in the tangram-type closure connection, which abutment surfaces extend in a direction transverse to the circumferential direction of the compression ring. In this case, the enlarged head of the tongue member is provided with a rounded transition between its side and transversely extending end faces while still maintaining a substantially rectangular relationship between the transversely extending abutment face at the beginning of the enlarged head and the corresponding adjacent longitudinally extending abutment face formed by the recess in the female member of the escutcheon-plate lock connection on the male member.

Furthermore, in accordance with a preferred embodiment of the present invention, the inner and outer compression ring surfaces in certain areas of the septematic closure are swaged to displace material to reduce the likelihood of disengagement of the septematic closure and to improve retention of the septematic closure against radial forces.

Drawings

The objects, features and advantages of the present invention will become more apparent by referring to the drawings and the following description in which an embodiment of the present invention is shown for illustrative purposes only, wherein:

FIG. 1 is a plan view of a tangram-type locking compression ring blank of the present invention in a flat condition;

FIG. 2 is an axial elevational view of a compression ring made from the blank shown in FIG. 1;

FIG. 3 is an enlarged view of the heptaplate type latching connection of the preferred embodiment of the present invention;

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 3;

FIG. 5 is a partial plan view of the prior art tangram type locking compression ring shown in FIG. 1 of the inventor's prior U.S. patent;

FIG. 6 is a partial plan view of the prior art heptaplate type closure connection shown in FIG. 2 of the inventor's prior patent;

FIG. 7 is a schematic front view of an apparatus for performing a swaging operation;

FIG. 8 is an enlarged cross-sectional view similar to FIG. 4 showing details of the area of the compression ring subjected to the swaging operation; and

fig. 9 is an enlarged sectional view showing a detail of the swage tooth.

Detailed Description

Referring now to the drawings in which like parts are designated by like reference numerals throughout the several views, reference numeral 10 generally designates a compression ring (fig. 2) formed from the blank 11 shown in fig. 1. As described in the above-mentioned patents, interengaging, cushioned abutment surfaces extending transversely along certain edges of the mechanical connection serve to absorb compressive and tensile forces in the compression ring, these abutment surfaces being similar to a heptagonal plate type connection and generally designated by the reference numeral 13. The male and female formations of the mechanical connection 13 comprising these abutment surfaces serve to join the two ends 11a and 11b of the blank 11. The projecting end 11b of the escutcheon plate type closure connection 13 includes a tongue catch 14, the tongue catch 14 being provided with an enlarged head 15 (see fig. 1 and 3). The enlarged head 15 includes laterally extending lugs 16 and 17 (see fig. 3), the two lugs 16 and 17 being defined by linear lateral abutment surfaces 31 and 32 and engaging in complementary shaped enlarged recesses 22 adjacent a channel-shaped recess 21, the channel-shaped recess 21 being adapted to mate with the tongue 14, and the channel-shaped recess 21 being disposed in a recess generally designated 20 at the end 11a of the blank 11 (see fig. 1). Thus, the tongue 14 and its enlarged head 15 are inserted into the channel-shaped recess 21 and the enlarged recess 22, respectively, in the recess 20, the recess 20 extending in the longitudinal direction of the blank 11 (fig. 1), so that the tongue 14 with its enlarged head 15 engages the abutment surfaces 23 and 24 from behind.

If the mechanical connection 13 of the compression ring according to the invention is subjected to tensile or compressive stresses, the region of the end 11a behind the abutment surfaces 23 and 24 tends to move laterally away from the tongue 14, as a result of which the tongue 14 together with its enlarged head 15 may be pulled or pushed out of the recess 20 by the opening of the channel-like recess 21. To counteract this tendency, two side lugs 18 and 19 are provided in the lateral regions of the male part of the mechanical connection on the end 11b, these two lugs 18 and 19 abutting against the longitudinally extending sides 25 'and 26' on the longitudinally extending parts 25 and 26 in the female part of the mechanical connection 13 to counteract any lateral bending of the two parts 25 and 26. It is precisely because of the special arrangement of the two lugs 18 and 19 that the mechanical connection of the ends 11a and 11b is effectively protected against tensile or compressive forces.

In the prior art embodiment of the present application shown in fig. 5, the enlarged head includes rounded side lugs having a semi-circular configuration, whereas in the prior art embodiment shown in fig. 6, the enlarged head has a rectangular configuration with right angles at its four corners.

It has now surprisingly been found that the holding capacity of the mechanical connection can be significantly increased if only the right-angled relationship of the two angles x and y of the enlarged head shown in fig. 6 is replaced by a rounded configuration. In order to obtain as large laterally extending abutment surfaces 23 and 24 as possible, it is necessary to maintain the right angle relationship between the laterally extending abutment surfaces 23, 24 and the side abutment surfaces 31, 32. On the other hand, the right angle relationship between the past side abutment surfaces 31, 32 and the laterally extending end surface 33 of the enlarged head 15 is now changed to a circular arc configuration containing a quarter circle with a very small radius. As a result, the presence of the additional material in the areas 41 and 42 of the concave portion on the end portion 11a reduces the risk of tearing and/or pulling off the side portions of the end portion 11 a. Tests have shown that significant improvements can be obtained with this new structure. The right angle relationship between the other adjacent abutment surfaces is actually maintained in order to maintain the transversely extending abutment surfaces, particularly the abutment surfaces 12 in the swaged region 50, as long as possible.

According to another feature of an embodiment of the invention, the joint formed along the mutually engaging abutment surfaces 12 and 33 is subjected to a swaging action, produced by using more or less conventional means, on the areas indicated by the broken lines in fig. 3 and designated by the reference numerals 50 and 51, to displace the material as shown in fig. 4 and 8, so as to reduce the possibility of relative movement of the compression ring between the two ends 11a and 11b in the radial direction.

Table I below shows: the snap-on capability of a compression ring with a swaged heptate plate lock connection is a significant improvement over the same compression ring with a non-swaged mechanical connection. In all tests, the compression rings were made of "Galfan" strip steel material, with a nominal diameter of 95.9 mm. After shrinking, the tape had a width of 10mm and a thickness of 1.2 mm. All test specimens are 99mm in diameter since all tests are performed using the compression ring in the as-manufactured state, i.e. before shrinking to show a greater holding capacity during transport. The swage test specimen had three swaged regions as shown by the dashed lines in fig. 3 and generally represented by reference numerals 50 and 51, whereby the swaging was performed in a symmetrical manner inside and outside the strip as shown in fig. 4 and 8. The test apparatus employs conventional operating principles with approximately pi-shaped, tapered segments forming an inner, small circular structure and an outer, large circular structure. The compression ring test specimen is thereby placed on the outer circumference of the segment and the tapered circular mandrel member is slowly passed through the inner circular opening of the segment in such a manner that the radial dimension of the tapered mandrel member gradually increases, thereby exerting a gradually increasing uniform radial force on the segment. The radial force at which the test specimen is destroyed can be easily determined by measuring the downward force on the conical mandrel member using, for example, a load cell located at the bottom of the mandrel member, multiplying the downward force by a constant 28.05. There were a total of 20 identical test specimens, except that 10 of them contained a non-swaged mechanical connection and the other 10 contained a swaged mechanical connection, with the test results shown in table I. Test results show that the holding capacity of a compression ring of the same type can be increased on average by more than 100% under the manufacturing conditions, i.e. before installation by shrinkage. The radial force when subjected to failure, i.e. when the mechanical connection is released, is expressed in newtons.

Radial pressure failure test

	Non-swage newtons	Swage newtons
			No.1No.2No.3No.4No.5No.6No.7No.8No.9No.10	347234246345274300283269275315	614599672613654640621724609628
Mean value of	288.8	637.4

TABLE I

The dimensions of a typical sample of compression rings of nominal diameter 95.9mm, strip width 10mm, strip thickness 1.2mm and made of "Galfan" strip steel material are as follows. It is obvious that these dimensions are only intended to illustrate one embodiment and do not constitute a limitation of the invention, since it is well within the reach of a person skilled in the art to vary these dimensions.

In this exemplary, non-limiting example of an embodiment in accordance with the invention, the length of the fastener strip having a width of 10mm is determined by the radial dimension required for the nominal diameter of the compressed loop after contraction. The length of the tongue from the transverse line coincident with abutment surface 12 to the transversely outermost abutment surface 33 of the enlarged head 15 is 7.5mm, the width of the enlarged head from the side abutment surface 31 to the other side abutment surface 32 is 6mm, the length of the lateral lugs 18 and 19 from the transverse line coincident with abutment surface 12 to the line coincident with abutment surface 44 is 2mm, the length of the transverse line coincident with abutment surface 44 to the surfaces 23, 24 is 2.5mm, and the radius of curvature of the enlarged head is 1 mm. The centrally located tongue 14 is 3mm wide, the lugs 18 and 19 1.5mm wide, the swaged region 50 is 2mm wide, the swaged region 51 is 4mm wide and the clamp strip is 1.2mm thick. All the above dimensions refer to the blank 11 in a flat condition.

As shown in fig. 4 and 8, material displacement is performed in a symmetrical manner on the outer portion 11' and the inner portion 11 "of the compression ring over the two regions 50 and 51 shown in fig. 3. As shown in fig. 8, each of the inner recesses 90 on the inner surface 11 'of the compression ring 10 and each of the outer recesses 91 on the outer surface 11 "of the compression ring 10, which are produced by swaging, have a depth of about 0.35 and are defined by the side surfaces 90a, 90b and 91a, 91b, respectively, whereby the side surfaces 90a, 90b and the side surfaces 91a, 91b subtend an angle of about 60 deg., and their intersection with each other and with the inner and outer surfaces 11" and 11' of the ring 11, respectively, are rounded with a radius of about 0.1 mm. The distance from the smaller side 90b to the cutting plane 92 representing, for example, the abutment surface 12 or 33 is approximately 0.6 mm.

Fig. 7 is a schematic view showing an apparatus for performing a swaging operation, which includes a core-shaped base member 70 having an outer upper surface 71 and an outer lower surface 72, each of which forms a portion of a circle having a radial dimension R the same as that of the inner surface of the machined compression ring. The stamp 75, driven with the required force in any generally known manner, can be guided to and fro in a relatively fixed machine part 76 for reciprocating movement during the swaging process. The core substrate 70 is thereby secured in any conventional manner (not shown) to the relatively stationary machine component 76 and a small projection 73 is provided on the surface 72 of the core substrate 70, which projection 73 engages, for example, a groove or small notch in the compression ring to properly position the compression ring for the swaging operation. Thus, both the base 70 and the stamp 75 are configured with small swage teeth (see FIG. 9) to perform the swaging operation. In one embodiment of the invention using a clamp ring of the type tested in table I, the swaging operation along abutment 33 has a width of about 4mm and in the region of abutment 12 a width of about 2 mm. The spacing between the outer surface 71 on the base member 70 and the stamp 75 in its extended position and the inner surfaces 74 and 77 of the mechanical part 76 is substantially equal to the thickness of the fastener strip.

Fig. 9 shows the shape of the swage teeth provided on the surface 74 of the die 75 and on the surface 71 of the base member 70 of the machine of fig. 7, the location of the swage teeth being such that material transfer occurs on the inner and outer surfaces 11 "and 11' of the strip material that make up the compression rings located in the swaged regions 50 and 51, as shown in fig. 8. Since the swage teeth have substantially the same shape on surfaces 74 and 71, only swage teeth 95 and 96 on surface 74 are shown in fig. 9. Each swage tooth 95 and 96 is defined by two sides 95a, 95b and 96a, 96b, respectively, while the angle between the respective sides 95a, 95b and 96a, 96b is about 60 °, respectively, and their points of intersection with each other and with the surface 74 are rounded with a radius of about 0.1 mm. The maximum outward protrusion distance of teeth 95 and 96 from surface 74 at the intersection of sides 95a, 95b and sides 96a, 96b is about 0.35 mm. The span of these teeth in the circumferential and width directions corresponds to the dimensions of the swaging regions 50 and 51 in fig. 3 and 8, whereby two such swage teeth 75 are provided spaced apart in the axial direction of the swaging stamp 75 for two swaging regions 50.

The following tables (fig. 2A-9A) and graphs (fig. 2B-9B) illustrate the improvement in retaining capability of the various compression rings shown in fig. 3 and 4, which are made of different materials, but are each provided with the above-described swaged heptate type closure. In all of these tests, the compression ring contracted its diameter by 4mm before the measurement. The measurements are again carried out on a machine in which the shrinking compression ring is placed along the circular outer surface of several pi-shaped tapering segments, so that a circular opening of smaller diameter is formed inside, whereby the conical mandrel is forced through this smaller opening under a predetermined downward force, which is measured by means of a load cell and the radial force is obtained therefrom. In the graphs shown in FIGS. 2B-9B, the radial force is given in units of daN (Newton x 10).

Although several embodiments according to the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the invention is not limited thereto and that various modifications and improvements can be easily made by those skilled in the art. For example, the swaging operation may be part of the overall automated manufacture of such compression rings, as described more fully in the present inventor's co-pending application (filed 5/21 1996 entitled "machine for automated manufacture of heptagonally locked compression rings", D/21563), the subject matter of which is hereby incorporated by reference into this application. It is therefore intended that the present invention not be limited to the details disclosed herein, but that it cover all modifications and variations included within the scope of the appended claims.

TABLE 2B

TABLE 3B

TABLE 4B

TABLE 5B

TABLE 6B

TABLE 7B

TABLE 8B

TABLE 9B

Claims (7)

1. A compression ring having a mechanical connection in the form of complementary female and male portions at respective ends (11a, 11b) of the compression ring, said male portion having a tongue-like extension (14) with an enlarged head (15) adapted to fit into a complementary shaped recess (22) in the female portion, wherein said head (15) comprises:

transverse abutment surfaces (23, 24) extending substantially perpendicular to the substantially longitudinally extending abutment surfaces of the tongue-like extension (14);

lateral abutment surfaces (31, 32) extending substantially in the longitudinal direction of the compression ring and extending in a substantially perpendicular manner to said transverse abutment surfaces (23, 24); and

a transverse end abutment surface (33),

characterized in that the lateral abutment surfaces (31, 32) extend through the circular arc-shaped structural part onto the end abutment surface (33).

2. The compression ring of claim 1, wherein said circular arc shaped structural portion substantially encircles 90 °.

3. A compression ring as claimed in claim 1 or 2, wherein said end portions (11a, 11b) are provided with additional substantially transversely extending and mutually engaging abutment surfaces (12, 44).

4. A compression ring according to claim 1, characterized in that at least along some of the joints of the mutually engaging abutment surfaces (33, 12) there are swaged material transfer areas (50, 51) to limit the possibility of relative radial movement between the ends, the material transfer areas (50, 51) being provided along the radially inner and outer surfaces of the compression ring in the area of the joints.

5. A compression ring as claimed in claim 4, wherein said material transfer zones (50, 51) are arranged substantially symmetrically on the radially inner and outer surfaces of a respective joint.

6. A compression ring according to claim 4, wherein said material transfer zones (50, 51) are realized by notches (90, 91) formed by swaging.

7. A method of forming a compression ring from a flat strip of material having a mechanical connection at its male and female ends, comprising the steps of: stamping a flat blank having a male end and a female end to form a complementary part of said mechanical connection, said mechanical connection having on its male part a tongue-like extension (14) with an enlarged head (15) and on its female part a complementary recess (22), wherein said head (15) comprises:

transverse abutment surfaces (23, 24) extending substantially perpendicular to the substantially longitudinally extending abutment surfaces of the tongue-like extension (14);

lateral abutment surfaces (31, 32) extending substantially in the longitudinal direction of the compression ring and extending in a substantially perpendicular manner to said transverse abutment surfaces (23, 24); and

a transverse end abutment surface (33),

characterized in that it further comprises the step of providing a transition from said lateral abutment surfaces (31, 32) to said end abutment surfaces (33) in the form of a circular arc.