FIXING STRUCTURE

Abstract: A fixing structure (A) in which screw engagement members (4) are applied to mating thread portions (3a) formed in a fixed member (3) through mounting holes (5a) provided in a mounting member (5) and having a larger diameter than the outer diameter of the screw engagement members (4) to hold the mounting member (5) of the fixed member (3), said fixing structure (A) is characterized by the provision of engaging members (6) of elastic material which have a free size outer diameter nearly equal to or smaller than the bore diameter of the through mounting holes (5a) of the mounting member (5) for engaging said screw engagement members (4), so that the elastic engaging members (6) radially expand as the screw engagement members (4) move toward engagement with the fixed member (3) to engage themselves with the outer circumfer­ ence or inner wall of said through mounting holes (5a) of the mounting member (5) for securely fixing said mounting member (5) to said fixed member (3).

Description: This invention relates to a fixing structure in which free mounting members are secured to fixed members using screw engagement members. Openings provided on distributing boards, machines and the like for maintenance purposes are conventionally fixed with covers (mounting members) to seal those openings. To fix a cover on an opening it has been a common practice to insert setscrews (screw engagement members) into female thread portions tapped around the opening on the body (fixed member) of a machine for example, through a plurality of mounting holes provided in the outer circumference of the cover, so that the head portions of the set screws will hold down the surface of the cover. In the fixing structure mentioned above, the bore diameter of the mounting holes is larger than the outer diameter of the set screws' male thread portions. At the same time, the bore diameter of the mounting holes is generally made smaller than the head portions of the setscrews. Because of this, when the cover is removed from the opening of the machine to do maintenance for example, all of the setscrews should be completely pulled out from the female thread portions. This tends to make the removal of the cover take time and to cause a risk of losing the setscrews which have been once pulled out. Furthermore, a fixing structure assembly comprising a fixed member provided with a female thread portion, a fixing structure and a mounting member which has a through mounting hole and which is to be fixed by the fixing structure on the fixed member is known from GB-A-2045377. This known fixing structure comprises: an engaging member of elastic material which has a free size outer diameter nearly equal to or smaller than the diameter of the through mounting hole; and a screw engagement member having a head and a male thread portion, the male thread portion being designed for threaded engagement with the mating female thread portion in the fixed member from the side of the fixed member facing the mounting member, the head having an outer diameter which is smaller than the diameter of the through mounting hole, and the head, at the side thereof adjacent to the male thread portion, having a surface portion for engaging and radially expanding the engaging member as the head is moved toward engagement with the fixed member. In this known fixing structure assembly the engaging member is a bush which has a cylindrical circumferential outer surface and an outwardly tapered conical through passage. The bush is received within the through mounting hole of the mounting member, and the wall of the conical through passage thereof is engaged by a complementary conical outer surface portion of the head of the screw engagement member. Upon tightening of the screw engagement member radial forces only are applied by the engaging member on the mounting member. Therefore the mounting member must have a substantial thickness to enable the application of a sufficient mounting force. In practical applications this requirement frequently is not fulfilled. This invention aims at removing the above mentioned disadvantages and providing an improved fixing structure. In conformity with one aspect of the present invention a fixing structure assembly comprising a fixed member provided with a female thread portion, a fixing structure and a mounting member which has a through mounting hole and which is to be fixed by said fixing structure on said fixed member, said fixing structure comprising: an engaging member of elastic material which has a free size outer diameter nearly equal to or smaller than the diameter of said through mounting hole; and a screw engagement member having a head and a male thread portion, said male thread portion being designed for threaded engagement with the mating female thread portion in said fixed member from the side of said fixed member facing said mounting member, said head having an outer diameter which is smaller than the diameter of said through mounting hole, and said head, at the side thereof adjacent to said male thread portion, having a surface portion for engaging and radially expanding said engaging member as said head is moved toward engagement with said fixed member, is characterized in that said engaging member is a ring-shaped metal spring having a circular, square or rectangular cross-section; and that said fixing structure further comprises a washer which has a thickness equal to that of said mounting member, has an outer diameter equal to that of said head, and is disposed on said male thread portion for supporting said engaging member between said inclined surface portion and said washer, such that upon tightening of said screw engagement member said radially expanding engaging member is urged against the end of said through mounting hole facing said head. In conformity with another aspect of the present invention a fixing structure assembly comprising a fixed member provided with a female thread portion, a fixing structure, and a mounting member which has a through mounting hole and which is to be fixed by said fixing structure on said fixed member, said fixing structure comprising: an engaging member of elastic material which has a free size outer diameter nearly equal to or smaller than the diameter of said through mounting hole; and a screw engagement member having a head and a male thread portion, said male thread portion being designed for threaded engagement with the mating female thread portion in said fixed member from the side of said fixed member facing said mounting member, said head having an outer diameter which is smaller than the diameter of said through mounting hole, and said head, at the side thereof adjacent to said male thread portion, having a surface portion for engaging and radially expanding said engaging member as said head is moved toward engagement with said fixed member, is characterized in that said engaging member is a ring-shaped metal spring having a circular, square or rectangular cross-section; and that the circumferential wall of said through mounting hole is outwardly tapered such that upon tightening of said screw engagement member said radially expanding engaging member is urged against said outwardly tapered mounting hole wall. The elastic engaging members then radially expand as the screw engagement members move toward engagement with the fixed member to engage themselves with the outer circumference or inner wall of said through mounting holes of the mounting member for securely fixing said mounting member to said fixed member. In the above mentioned fixing structure assemblies the screw engagement members which will be always in engagement with the engaging members are previously screwed into the fixed member, upon which the mounting member with the engaging members is mounted through the holes provided therein. By tightening the screw engagement members the engaging members radially expand as the screw engagement members move toward engagement with the fixed member to engage themselves with the outer circumference or inner wall of said through mounting holes of the mounting member, so that said mounting member is held to the fixed member. When the screw engagement members are moved toward disengagement for removing the mounting member from the fixed member, the engaging members engaged with the mounting member will shrink radially to release themselves from the mounting member. Thus the mounting member can be removed from the fixed member without pulling out the screw engagement members. Therefore, by applying the above mentioned structure to the fixing means of a cover on the opening of a machine for example, the loading and unloading of the cover can be made very simple, and in addition, a risk of losing the screw engagement members is securely avoided. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view showing one embodiment of the fixing structure according to the present invention; Fig. 2 is a perspective view of screw engagement members, engaging members and washers which compose said fixing structure; Fig. 3 is an explanatory drawing showing the steps of fixing a mounting member to a fixed member by way of said fixing structure; Fig. 4 is a sectional view showing another embodiment of the fixing structure according to the present invention; and Fig. 5 is a sectional view showing still another embodiment of the fixing structure according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment of the fixing structure A, as shown in Figs. 1 and 2, when a cover (mounting member) 5 is fixed to the body (fixed member) 3 of a machine for example using setscrews (screw engagement members) 4 to be screwed into mating thread portions 3a formed around the opening (not shown) of the body 3 through a plurality of mounting holes 5a provided in the cover 5 whose bore diameter is larger than the outer diameter of the head 4a of each setscrew 4, there are utilized engaging members 6 of elastic material, which have a free size outer diameter nearly equal to or smaller than the bore diameter of each mounting hole 5a and are engaged with the heads 4a of the setscrews 4, radially expand as the setscrews 4 move toward engagement with the body 3 (direction shown by the arrow 8) to engage themselves with the outer circumference of said through mounting through holes 5a of the cover 5, so it is fixed to the body 3. At the lower circumference of the head 4a of the setscrew 4 is formed a supporting part 4b having an inclined plane in contact with the inner circumference of each said engaging member 6 for radially expanding the engaging member 6, and at the central portion under the head 4a is formed a male thread portion 4c. Over the male thread portion 4c is inserted a washer 7 for supporting the engaging member 6 with the supporting part 4b. The washer 7 is made to have a thickness equal to that of the cover 5 and an outer diameter equal to that of the head 4a of the setscrew 4. Each of the through hole 5a of the cover 5 is used for inserting through the head 4a of the setscrew 4, engaging member 6 and washer 7 when the cover 5 is mounted to or removed from the body 3. The engaging member 6 is made of an elastic material such as a metal spring member of a circular sectional view which is formed into a ring, and radially expands as the setscrew 4 moves toward engagement with the body 3 to engage the lower surface thereof with the outer circumference of the through mounting hole 5a at the upper surface of the cover 5, so that the cover 5 is held to the body 3. The procedures to setup the fixing structure A will now be explained referring to Fig. 3. In the first place, the engaging member 6 and washer 7 are fitted to the setscrew 4, and this setscrew 4 is then screwed into each one of the mating thread portions 3a of the body 3 until the engaging member 6 is about to be expanded by the insertion of the setscrew 4 with the supporting part 4b. The cover 5 is placed over the body 3 with each of the through hole 5a thereof passed through with the head 4a of the setscrew 4, engaging member 6 and washer 7. The set-screw 4 is then further screwed down in the direction of the arrow 8. This makes that the engaging member 6 radially expands with the supporting part 4b of the setscrew 4 to cause the lower surface of the engaging member 6 to engage with the outer circumference of the through hole 5a, so that the cover 5 is fixed to the body 3. When the cover 5 is removed from the body 3, the reverse of the procedures mentioned above will be performed. That is, the setscrew 4 is moved toward disengagement (direction shown by the arrow 9) to cause the engaging member 6 to shrink radially for releasing the engagement between the lower surface of the engaging member 6 and the outer circumference of the through hole 5a. Thus the cover 5 can easily be removed from the body 3 without pulling out the setscrew 4 therefrom. In the fixing structure A it is one of the essential factors for the setup thereof that the engaging member 6 should be expanded as the setscrew 4 moves toward engagement. To this end the shape of the support part 4b of the setscrew 4 may not be limited to have an inclined plane as in the above embodiment. Also, the cross sectional view of the engaging member 6 may not be limited to be circular. Therefore, it may be square or rectangular. The other embodiments of the fixing structures B, C, and D according to the present invention will now be explained in order referring to Figs. 4, 5, and 6. The fixing structure B has, as shown in Fig. 4, a through hole 5a whose inner circumference wall is tapered upward. The engagement of this tapered inner circumference wall of the through hole 5a with an engaging member 6 which radially expands with the movement of a setscrew 4 will fix a cover 5 to a body 3. In the fixing structure C, as shown in Fig. 5, there is provided a washer 7 similar to that in the fixing structure A but is made integral with a body 3. Although using setscrews as the screw engagement member has been described in the embodiments shown above, nuts for mating male screws (bolts for example) proviously provided in the body may also be utilized to compose the fixing structure according to the present invention. The fixing structure of the invention can be applied to any system in which a mounting member is fixed to a fixed member without being limited by the embodiments shown above in which a cover is fixed to a machine body.

Claims: A fixing structure assembly comprising a fixed member (3) provided with a female thread portion (3a), a fixing structure (A, C) and a mounting member (5) which has a through mounting hole (5a) and which is to be fixed by said fixing structure on said fixed member, said fixing structure comprising: an engaging member (6) of elastic material which has a free size outer diameter nearly equal to or smaller than the diameter of said through mounting hole (5a); and a screw engagement member (4) having a head (4a) and a male thread portion (4c), said male thread portion (4c) being designed for threaded engagement with the mating female thread portion (3a) in said fixed member (3) from the side of said fixed member (3) facing said mounting member (5), said head (4a) having an outer diameter which is smaller than the diameter of said through mounting hole (5a), and said head (4a), at the side thereof adjacent to said male thread portion (4c), having a surface portion (4b) for engaging and radially expanding said engaging member (6) as said head (4a) is moved toward engagement with said fixed member (3), characterized in that said engaging member (6) is a ring-shaped metal spring having a circular, square or rectangular cross-section; and that said fixing structure (A, C) further comprises a washer (7) which has a thickness equal to that of said mounting member (5), has an outer diameter equal to that of said head (4a), and is disposed on said male thread portion (4c) for supporting said engaging member (6) between said inclined surface portion (4b) and said washer (7), such that upon tightening of said screw engagement member (4) said radially expanding engaging member (6) is urged against the end of said through mounting hole (5a) facing said head (4a). The fixing structure assembly of claim 1 wherein said washer (7) is a separate part. The fixing structure assembly of claim 1 wherein said washer (7) is integral with said fixed member (3). A fixing structure assembly comprising a fixed member (3) provided with a female thread portion (3a), a fixing structure (B), and a mounting member (5) which has a through mounting hole (5a) and which is to be fixed by said fixing structure on said fixed member, said fixing structure comprising: an engaging member (6) of elastic material which has a free size outer diameter nearly equal to or smaller than the diameter of said through mounting hole (5a); and a screw engagement member (4) having a head (4a) and a male thread portion (4c), said male thread portion (4c) being designed for threaded engagement with the mating female thread portion (3a) in said fixed member (3) from the side of said fixed member (3) facing said mounting member (5), said head (4a) having an outer diameter which is smaller than the diameter of said through mounting hole (5a), and said head (4a), at the side thereof adjacent to said male thread portion (4c), having a surface portion (4b) for engaging and radially expanding said engaging member (6) as said head (4a) is moved toward engagement with said fixed member (3), characterized in that said engaging member (6) is a ring-shaped metal spring having a circular, square or rectangular cross-section; and that the circumferential wall of said through mounting hole (5a) is outwardly tapered such that upon tightening of said screw engagement member (4) said radially expanding engaging member (6) is urged against said outwardly tapered mounting hole wall.

Inventors: KANAZAWA, HIDEKI
Applicants: KANAZAWA, HIDEKI
Application year: 1988
Main classification: F16B5
IPC codes: F16B5, F16B43