PROTECTIVE CAP FOR BOLTS WITH NUTS

Abstract: A cap (1) for protecting bolts (8) and nuts (9) protruding from a surface (11) against damaging effects from their surrounding environment in and on water and on land. The cap comprises an internally threaded sleeve (2), closed at one end thereof and joined to a skirt (3) at the opposite, open end thereof. The interior of the sleeve is provided with at least one longitudinal groove (6), and a protective agent, for example grease, is provided inside the sleeve (2). When the cap (1) is screwed down over a bolt (8) and nut (9) that protrude from a surface (11), this action forces the protective agent, via the groove (6), to penetrate into the mating threaded sections (5, 8') of the sleeve (2) and bolt (8) and to flow down the walls of the skirt and around the free surfaces of the nut (9), as well as to penetrate into the mating threaded sections of the nut (9) and bolt (8) and in between the nut (9) and the surface (11), because the bottom edge of the skirt (3), as the cap is screwed down onto the bolt (8), is forced into contact against the surface (11), thereby causing increased pressure on the protective agent inside the skirt (3).

Description: PROTECTIVE CAP FOR BOLTS WITH NUTS The present invention relates to a cap for protecting a nut and bolt projecting outwardly from a surface against damage from the surrounding environment, consisting of an inter- nally threaded sleeve, closed at one . end thereof, for engagement with the bolt, and a skirt connected to the open end of the sleeve for covering and surrounding the free surfaces of the nut. A protective cap of this type is disclosed in German Patent DOS No. 3,126,959 A-l. According to the patent specifica¬ tion, the sleeve and skirt are made as two separate parts of, respectively, a rigid plastic material and a softer plastic material, the two parts being provided with mating coupling means. The two parts can be snapped together to join them and after coupling they can also be rotated in relation to each other. The skirt is formed with a hexagonal cross section adapted to the hexagonal nut config uration. At the closed end, the sleeve is provided with a lubrication nipple for the injection of grease. It also has an opening covered by a membrane in the interior of the sleeve, and the membrane will bulge out through the opening to indicate an overpressure in the sleeve. When this cap is being used, the sleeve is screwed onto the outwardly protruding bolt as the skirt is brought into alignment with the nut, and the skirt is pressed further down on the nut as the sleeve is screwed down. When the sleeve has been screwed down as far as it will go, the skirt will not fully reach down to the surface from which the bolt protrudes. Thereafter, grease is injected into the sleeve through the lubrication nipple, filling the cavity of the sleeve, penetrating into the mating threaded sections of the sleeve and bolt, and will also be forced into the space between the skirt and the free surfaces of the nut, eventually exiting at the bottom edge of the cap between the free edge of the skirt and the plate. The pressure of the lubricant will cause the membrane to bulge out slightly through the opening at the closed end of the sleeve, providing visual indication that the protective agent, i.e. grease, has been injected into the protective cap. The prior art protective cap consists of two separate parts which must be manufactured separately and assembled prior to use. Furthermore, after the cap has been screwed down over the bolt and nut, the protective lubricant must be injected through the nipple by means of a grease gun or the like, which thus must be brought to the location where the cap is to be installed. The object of the present invention is to provide a pro- tective cap which has a simpler construction, thus making it less expensive to manufacture, and which enables a simultaneous injection of protective lubricant as the cap is being screwed down over the bolt. The lubricant will penetrate into the mating threaded sections of the sleeve and bolt as well as around the free surfaces of the nut, and will also partially penetrate into the space between the mating threaded sections of the bolt and nut and between the nut and the adjacent surface or plate through which the bolt protrudes. The above objects are obtained by means of the character¬ izing features recited in the characterizing clause of the appurtenant independent claim 1 and the succeeding dependent claims. An embodiment of the invention will be described in greater detail in the following with reference to the accompanying drawings, wherein: Figure 1 shows the cap in side view, and Figure 2 shows the cap in axial cross section, installed on OMPI ^NATlO a bolt and nut that project upwardly from a plate. The cap shown in Figures 1 and 2 consists of an internally threaded sleeve 2, preferably made of plastic and closed at one end 2* , which in the exemplary embodiment is formed wit a faceted configuration corresponding to a hexagonal nut an is intended for engagement with a similarly-formed tool for screwing the cap onto the bolt. The opposite, open end 2" of the sleeve 2 is joined to a skirt 3 via a conical trans- ition section 4 whose wall thickness gradually diminishes from the sleeve 2 toward the skirt 3. The inside wall of the sleeve 2, which is provided with threads 5, also has at least one, and preferably two, longitudinal grooves 6 that extend from the closed end 2 * of the sleeve 2 to its open end 2". The grooves preferably have a depth corresponding to the depth of the screw threads. The cap is intended to be delivered with the protective agent/lubricant 7 already provided in the sleeve 2. When the cap 1 is screwed down over a bolt 8 with a nut 9 which project through a hole 10 in a plate 11, the cavity within the sleeve 2 above the end of the bolt 8 will be reduced in volume. Thus the grease 7 within the sleeve 2 will be forced to enter the grooves 6 and will penetrate into the mating threaded sections, 8' and 5, of the bolt 8 and sleeve 2 respectively, and into the space defined by the skirt 3 with the conical transition section 4 and the free surfaces of the nut 9. The lubricant will therefore cover the accessible parts of the bolt 8 and nut 9, and it will also seek to penetrate into the mating threaded sections of the bolt 8 and nut 9 as well as into the space between the nut 9 and plate 11, because as the cap is being screwed down over the bolt 8, the skirt will be urged against the surface 11, thereby forming an enclosed space within the skirt 3 which becomes filled with lubricant, the latter having been forced to enter the abovesaid areas owing to the increased pressure on the lubricant as the cap 1 is screwed down. In the embodiment described above, the skirt 3 can be made of a rigid material, since the skirt, as mentioned, has a larger diameter than the maximum cross section of the nut 9. Alternately, the skirt 3 can be made with a thinner wall thickness than the wall thickness of the sleeve 2, such that the wall of the skirt 3 will be flexible, especially when the cap is manufactured of a plastics material. In that case, the skirt 3 can be made with a somewhat smaller inside diameter than the diameter of the circle circum¬ scribed by the nut, and the skirt 3, as the cap 1 is being screwed onto the bolt 8, will conform to the side surfaces of the nut 9, with the result that less lubricant will be required for filling the space between the skirt 3 and the nut 9. The skirt 3 can also be made flexible by abricating it of a softer material than the rigid material of the sleeve 2. During fabrication, for example by pressure die- casting, these materials are caused to conjoin at the transition section 4 between the skirt 3 and sleeve 2. The protective cap according to the present invention can be manufactured in a single operation. The cap 1, when it has been screwed down over the bolt 8 and nut 9, comprises a cavity above the end of the bolt 8 which is filled with a protective agent, for example grease. The pressure caused by the action of screwing down the cap onto the bolt 8 causes the lubricant to penetrate into the mating threaded sections 8',5 of the bolt 8 and sleeve 2, as well as to cover the free surfaces of the nut 9 and to penetrate partly into the mating threaded sections of the nut 9 and bolt 8, as well as into the space between the nut 9 and the adjacent plate surface 11 containing the hole 10 through which the bolt passes. OMP τ

Claims: Patent Claims 1. A cap (1) for protecting bolts (8) and nuts (9) protruding from a surface (11). against damage from the surrounding environment, consisting of an internally threaded sleeve (2)., closed at one end (2') thereof and intended to engage with the bolt (8) , and a skirt (3) joined to the opposite, open end (2") of the sleeve (2) and intended to cover and surround the free surfaces of the nut (9)., wherein said cap, when installed in the screwed- down position on the bolt, comprises a cavity above the end of the bolt (8) that is filled with a protective agent, i.e grease, and wherein said protective agent as a result of the applied pressure as the cap is being screwed down is forced to penetrate into the mating threaded sections (8', 5) of the bolt (8) and sleeve (2) and to cover the free surfaces of the nut (9) , characterized in that the sleeve (2). and skirt (3) constitute a single, integral member, wherein the effective depth of the skirt (3) is at least equal to the height of the nut (9) , and wherein the inter¬ nally threaded interior wall surface (5) of the sleeve (2) has at least one longitudinal groove (6). extending from the closed end (2*) to the open end (2") of the sleeve. 2. A protective cap according to claim 1, character¬ ized in that the skirt (3) is flexible and has an inside diameter that is smaller than the diameter of the circle circumscribed by the nut (9).. 3. A protective cap according to claim 2, character¬ ized in that the wall of the skirt (3). is thinner than the wall of the sleeve (2). 4. A protective cap according to claim 3, character- ized by a conical transition section (4) between the sleeve (2) and skirt (3). whose wall thickness gradually diminishes from the sleeve (2) toward the skirt (3).. "gTTRE , OMPI < IPO 5. A protective cap according to any of the preceding claims, characterized in that the sleeve (2) of the cap (1). contains a protective agent (71, for example grease.

Inventors: JANSEN JOHAN, JANSEN, JOHAN
Applicants: SOERLANDETS ALUMINIUMPROD, A/S SOERLANDETS ALUMINIUMPRODUKTER
Application year: 1984
Main classification: F16B37
IPC codes: F16B33, F16B37