GB2282202A

GB2282202A - Lock nut capable of engaging resiliently another nut

Info

Publication number: GB2282202A
Application number: GB9419444A
Authority: GB
Inventors: Chih-Chung Chiang
Original assignee: CHIANG CHIH CHUNG
Current assignee: CHIANG CHIH CHUNG
Priority date: 1993-09-28
Filing date: 1994-09-27
Publication date: 1995-03-29
Anticipated expiration: 2014-09-27
Also published as: DE19503962A1; GB9419444D0; FR2710706A1; FR2710706B1; CN1108360A; CA2132943A1; CN1042168C; GB2282202B; CA2132943C; AU671769B2; AU7421894A

Description

HALF NUT CAPABLE OF ENGAGING RESILIENTLY ANOTHER HALF NUT This invention relates to a half nut, more particularly to a half nut which is capable of engaging resiliently another half nut so as to form a nut member for fastening objects together with a threaded bolt.

According to the U. S. Pat. No. 5,248,232 , there is disclosed a nut and bolt set which includes a nut member having two halves and a threaded bolt engageable with the two halves. The combination of the two halves together with the threaded bolt provides a locking mechanism which does not easily get loose when an external force is applied thereon.

The main object of the present invention is to improve the structure of one of the half nuts of the nut member so that a resilient abutting engagement between the half nut can be achieved when the half nuts are used to fasten objects together with a threaded bolt.

Accordingly, the half nut of this invention has a short shank with an external screw thread thereon, and an inner wall which confines an axial bore therethrough. The inner wall of the half nut has an internal screw thread with a first screw pitch. The external screw thread of the half nut has a second screw pitch different from the first screw pitch. The internal and external screw threads of the half nut are substantially concentric with each other. The external screw thread of the half nut is defined by substantially constant major and minor radii, while the internal screw thread is defined by substantially constant greatest and shortest radii. The internal screw thread of the half nut has a constant halfbreadth which is greater than a difference between the minor and greatest radii.

In the disclosed embodiment, the first screw pitch of the internal screw thread of the half nut is greater than the second screw pitch of the external screw thread of the half nut.

In one embodiment, the minor radius of the external screw thread is greater than the greatest radius of the internal screw thread.

In another embodiment, the greatest radius of the internal screw thread is greater than the minor radius of the external screw thread.

The half nut of this invention cooperates with another half nut and a threaded bolt to form a fixing means which consequently provides a resilient abutting engagement when the fixing means is used to fasten objects together.

Other features and advantages of the present invention will become more apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, in which: Figures 1(A) and 1(B) show cross sectional views of two halves of a nut member of the present invention; Figure 2 is an enlarged view of the circle "F" shown in Fig. 1; Figure 3 shows the half nut of the present invention when cooperating with a threaded bolt to fasten objects together; Figure 4 shows the half nut of the present invention when cooperating with the threaded bolt and another half nut of the nut member to fasten two objects together; Figure 5 illustrates the directions of forces which are present in the two halves of the nut member after two objects have been fastened together with the use of the same;; Figure 6 shows another preferred embodiment of the half nut of the present invention together with another half nut; and Figure 7 shows the another preferred embodiment of the present invention when cooperating with the threaded bolt and another half nut of the nut member.

Referring to Figures 1(A) and 1(B), a fixing means includes a nut member and a threaded bolt to be inserted threadedly in the nut member. The nut member includes a first half (1) and a second half (2). The first half (1) includes a short shank (12) with a predetermined length (Ll) and an external screw thread (120) thereon, and an inner wall (13) which confines an axial bore therein and which has an internal screw thread (130) with a first screw pitch. The external screw thread (120) of the first half (1) has a second screw pitch which is different from the first screw pitch of the internal screw thread (130), and the internal and external threads (120, 130) are substantially concentric with each other.

The second half (2) has a threaded bore with first and second sections (210, 220) of differing radii. The second section (220) is narrower than the first section (210) and has the first screw pitch. The second section (210) has the second screw pitch and is engageable with the external screw thread (130) of the first half (1).

Referring to Figure 2, the external screw thread (120) of the first half (l) is defined by a substantially constant major radius (dl) which is a vertical length between the dotted line (P) and the axis (C) of the first half 1, and a substantially constant minor radius (d2) which is a vertical length between the dotted line (N) and the axis (C).The internal screw thread (130) of the first half (1) is defined by a substantially constant greatest radius (d3) which is a vertical length between the dotted line (M) and the axis (C) of the first half-(l), and a substantially constant shortest radius (d4) which is a vertical length between the dotted line (Q) and the axis (C) of the first half (1). The minor radius (d2) of the external screw thread (120) of the first half (1) is greater than the greatest radius (d3) of the internal screw thread (130). The internal screw thread (130) has a constant half-breadth (X) which is greater than a difference (Y) between the minor and greatest radii (d2, d3).The constant half-breadth (X) is a cross-sectional width which is measured at half of a vertical height between a tip point and a bottom of the internal screw thread 120, i. e. between the dotted lines (M) and (Q). The dotted line (M), which is drawn horizontally at the distal end points of the greatest radii (d3), is nearer to the axis (C) when compared to the dotted line (N.) which is drawn horizontally at the distal end points of the minor radii (d2).

Referring to Fig. 3, when in use, the threaded bolt (3) is inserted through two objects (so) and the first half (1) is screwed onto the threaded bolt (2) . A washer (31) can be provided between the first half (1) and the objects (90). Note that the first screw pitch of the internal screw thread (130) is greater than the second screw pitch of the external screw thread (120) of the first half (1). The threaded bolt (3) has the same pitch as the internal screw thread (130) of the first half (1) such that, when the latter is tightened relative to the former, an axial tensile and compression force is generated between the threaded bolt (3) and the internal screw thread (130) of the first half (1).The force correspondingly causes the threaded bolt (3) and the first half (1) to move in opposed directions from the objects (90), thereby fastening the latter. Note that, since the head portion toll) of the first half (1) has a thickness which is greater than the shank (12) and therefore possesses a greater strength, deformation of the thread within the shank (12) is more severe than that within the head portion (11). The dotted circle (A) suffers the greatest thread deformation while the dotted circle (C) suffers the least thread deformation.

The shank portion (12) of the first half (1), being weaker than the head portion (11), is correspondingly compressed axially, wherein the shank portion (12) contracts such that it possesses a length tL2) which is shorter than the length (L1), as shown in Fig. 1.

Referring to Figure 4, the second half (2) is tightened on the external screw thread (120) of the first half (1). Because the first and second sections (210, 220) have differing screw pitches, and since the screw pitch of the second section (220) is greater than the screw pitch of the first section (210), a full turn of the second half (2) causes the second section (220) to move a full length of its screw pitch while the first section (210) moves a length greater that its screw pitch, thereby compressing the first section (210) of the second half (2) farther toward the first half (1).Thus, the short shank (12) of the first half (1) is compressed axially by the rotation of the second half (2) relative to the shank (12) of the second half (2) such that the length of the shank (12) shortens to (L3) which is shorter than the length (L2) of the shank (12) before the second half (2) is threaded thereon. Under such a condition, a resilient abutting engagement is generated between the external screw thread (120) of the first half (1) and the second section (220) of the second half (2) due to the thickness reduction at the shank (12). The portion in the dotted circle (C1) suffers the most severe thread deformation while the portion in the dotted circle (A') suffers the least thread deformation.Note that the forces which are generated by the first and second halves (1, 2) after the first half (1) has been threaded on the threaded bolt (3) and the second half (2) has been threaded on the shank (12) of the first half (1) are counter-balanced such that they provide firm engagement between the objects (90).

Referring to Fig. 5, note that the objects (90) are engaged stationarily after the first half (1) is tightened on the threaded bolt (3). Under this condition, the threaded bolt 3 causes a compression force (P) on the objects (90) which is countered by the force (P1) generated between the first half (1) and the threaded bolt (3). When the second half (2) is tightened relative to the shank (12) of the first half (1), an axial compression force (Ps) is produced between the external screw thread (120) of the first half (1) and the first section (210) of the second half (2). When the objects (90) are at a stationary position, the compression force (Ps) is equivalent to the compression force (P1) which is produced by the first half (1).In case an external force which is greater than (Ps) is applied on the fastened objects (90), the force (P1) serves as a compensating force to prevent the fastened objects (90) from being moved.

Referring to Figure 6, in another preferred embodiment, the half nut has an external screw thread 520 formed on the short shank 52 and an internal screw thread 530 formed on an inner wall surface which confines an axial bore therethrough. The internal screw thread 530 has a constant half-breadth (T) which is greater than the difference (S) between the minor and greatest diameters d5, d6. In this embodiment, the greatest diameter d5 of the internal screw thread 530 is greater than the minor diameter d6 of the external screw thread 520. Thus a thickness between the internal and external screw threads 520, 530 is accordingly reduced so the tips of the internal and external screw threads 520, 530 closely overlap with one another.

In use, the threaded bolt 7 is inserted through the first half 5 and the second half 6 is threaded on the latter such that an axial tensile and compression force is generated between the internal screw thread 530 and the threaded bolt 7 at the positions (H) and (I). When the second half 6 is sleeved so as to be tightened on the shank 52 of the first half 5, an abutting engagement is generated at the position (G), an axial tensile and compression force is generated at the position (K), while a resilient abutting engagement is generated at the positions (J) between the external screw thread of the short shank 52 of the first half 5 and the internal screw thread of the first section 610 of the second half 6. Therefore, the engagement provided when the half nut 5 of the present invention is firmer than that disclosed in the previously cited U. S. Patent.

As explained above, the improved structure of the first half (1) of the nut member provides a resilient abutting engagement in cooperation with the second half (2) and the threaded bolt (3). Thus, the objects (90) fastened by the nut-and-bolt set which includes the half nut (1) of the present invention is firmer when compared to the conventional nut and bolt set.

With the invention thus explained, it is obvious to those skilled in the art that various modifications and variations can be made without departing from the scope and spirit thereof. It is therefore intended that this invention be limited only as indicated in the appended claims.

Claims

CLAIMS:

1. A half nut having a short shank with an external screw thread thereon and an inner wall confining an axial hole, said inner wall having an internal screw thread, said internal screw thread of said half nut having a first screw pitch, said external screw thread of said half nut having a second screw pitch different from said first screw pitch, said internal and external threads being substantially concentric with one another, said external screw thread of said half nut being defined by substantially constant major and minor radii, said internal screw thread of said half nut being defined by substantially constant greatest and shortest radii, said half nut being characterized in that said internal screw thread having a constant half-breadth which is greater than a difference between said minor and greatest radii.

2. The half nut as defined in Claim 1, characterized in that said minor radius of said external screw thread is equivalent to said greatest radius of said internal screw thread.

3. The half nut as defined in Claim 1, characterized in that said greatest radius of said internal screw thread is greater than said minor radius of said external screw thread.

4. The half nut as defined in Claim 1, characterized in that said internal screw thread has a screw pitch which is greater than a screw pitch of said external screw thread.

5. The half nut substantially as described hereinbefore with reference to and as illustrated in Figures 1 to 4, Figure 6 or Figure 7 of the accompanying drawings.