Split bolt

Abstract

Disclosed is a split-bolt having an improved wedge for separating the two bolt sections into threaded engagement within a nut. The wedge can be easily extracted from between the separated bolt segments by grasping generally cylindrical bosses on the wedge. The bosses are also conveniently accessible with a tool when the wedge is tightly bound by the sections, and thus unextractable by hand.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an improved split-bolt for use in combination with an insert embedded in a concrete slab to provide for the attachment to the slab of a detachable means for lifting the object.

In recent years, a form of building construction referred to as the tilt-up slab method has come into rather wide usage. In a tilt-up slab building, large concrete slabs are cast on the floor of the building or on a level ground surface. The concrete slabs are then lifted to a vertical position and interconnected to form the walls of the building.

The means used for lifting the slabs must be removable after the slabs have been lifted into place to present a smooth surface on the walls of the building. Generally, the lifting attachments are installed and removed at the building site. Therefore, they should be easily and rapidly installed and removed in order to save the maximum time.

One practice is to embed a nut member or insert in the concrete slab and then to attach a lifting eye to the slab by passing a bolt through the eye and threading it into the nut member or insert. While this provides a satisfactory anchoring for the lifting eye, it requires threading the bolt into the insert. Since the insert is embedded in the concrete when the slab is originally poured, small particles of concrete may be deposited on the thread surfaces of the bolt means. The presence of concrete on the thread surfaces will probably require the use of a wrench to thread the bolt into the insert. Considerable time is expended resulting in increases in the time required to erect the walls. Additional time is expended when a wrench is required to remove the bolt.

U.S. Pat. No. 3,456,547 solves some of the above problems by providing a bolt means which is rapidly inserted in a nut means or insert and requires only a partial revolution to lock the bolt securely in place. The bolt means is formed from a pair of separate longitudinal cylindrical segments such as are formed when a conventional bolt is split along its longitudinal axis into two bolt halves. A portion of the bolt along the longitudinal axis is removed so that when the two segments are placed together, they may be easily inserted into the nut means.

After the two bolt segments are inserted in the nut means, a key member or wedge is positioned between the bolt segments to separate them into engagement with the female threads on the nut means. To remove the bolt, the key is withdrawn and the two segments of the bolt are brought together. This disengages the threaded surfaces and permits withdrawal of the bolt.

The split-bolt disclosed in U.S. Pat. No. 3,456,547 is highly effective, but it has a disadvantage in that the wedge, or "key" as it is referred to in the patent, is not readily removed once the bolt is in use. After the slab is lifted and installed, the wedge must be extracted from between the bolt segments in order to remove the bolt. Tab or ear means are disclosed in U.S. Pat. No. 3,456,547 for gripping and lifting the wedge, but these means have proved ineffective. The forces of installing and securing the bolt, as well as lifting and transporting the object frequently cause the key to become tightly gripped or wedged between the bolt portions. The tab or ear means of U.S. Pat. No. 3,456,547 are essentially flush with the sides of the bolt. As such, they are neither effective nor efficient for grasping the wedge, either by hand or with a tool. Since the purpose of using a split-bolt is to save time, the key disclosed in U.S. Pat. No. 3,456,547 tends to defeat that purpose.

A need therefore exists for an improved split-bolt having an improved key or wedge means which can be used to extract the wedge quickly, simply and effectively from between the bolt portions when the bolt must be removed from the opening in which it has been inserted, e.g., a coil insert.

SUMMARY OF THE INVENTION

The invention is directed to an improved bolt, and in particular to an improved split-bolt for use in combination with an embedded anchoring means for detachably securing a lifting means to concrete slab or the like.

The split-bolt of the invention is an improvement over the prior art split-bolts because it provides a simple and effective means for extracting the key or wedge which space the bolt segments. In the preferred embodiment, cylindrically shaped bosses are provided on both sides of one end of the wedge or key which is extended to protrude from between the bolt segments. When it is desired to remove the wedge, the bosses can be grasped by hand to remove the wedge quickly. If the wedge is held tightly between the bolt segments, an instrument or tool, e.g., a claw hammer, can be used to grasp the head of the wedge via the bosses to extract the wedge. The bosses provide a means for grasping the key to apply a longitudinal, or upward, force to the key to extract it from between the bolt segments.

Also, the bosses on the head of the wedge are arranged so that the head of the bolt will provide a convenient fulcrum against which a lever means, e.g., a claw hammer, can work to apply the upward force to the bosses and the wedge. Thus a means is provided for simply and quickly extracting the wedge. This in turn results in the bolt being quickly and conveniently removed from any threaded opening in which it may be installed.

It is therefore an object of this invention to provide an improved split-bolt having a readily removable wedge.

It is a further object of this invention to provide an improved split-bolt having a wedge having cylindrical bosses whereby the wedge may be extracted simply and quickly.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings

FIG. 1 is an exploded view of the improved split-bolt of the invention;

FIG. 2 is a perspective view of a split-bolt of the invention showing how the wedge may be readily removed;

FIG. 3 is an exploded perspective view of an insert for use with a split-bolt of the invention;

FIG. 4 is a perspective view of a split-bolt of the invention used to secure a lifting ring; and

FIG. 5 is a partial cross-sectional view of a split-bolt of the invention securing a lifting ring.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows the improved split-bolt 10 as comprised of substantially identical segments 11 and 12 which may be formed individually or may be formed by longitudinally splitting a bolt and removing a portion of it. The main requirement of the two bolt segments 11 and 12 is that when their opposing inner faces 13 and 14 are in contact, their overall diameter is slightly less than the diameter of the bolt at its full radial extension, i.e., the diameter of the original bolt or the total diameter of the bolt segments and the wedge inserted between the segments.

Edges 15-17 of segments 11 and 12 may be relieved so that the diameter across generally flat surfaces 13 and 14 is also slightly less than the diameter of the bolt when it is at its full radial extension. When the two bolt segments are formed as described, it is possible to insert the two segments into an opening the size of the bolt at its full radial extension, e.g., a threaded coil insert in a pre-cast concrete block. Thus in the example, the overall diameter of the two segments in face-to-face relationship will be less than the minor diameter of the thread in the coil insert.

The top of each bolt segments 11 and 12 comprises enlarged head portions 18 and 19 which when viewed overall resemble a normal bolt head. As illustrated in FIGS. 1 and 2, head sections 18 and 19 define, overall, a hexagonal head.

Wedge 22 is an extended generally rectangular piece or member, having generally flat, generally parallel faces, insertable between bolt segments 11 and 12 to expand and space them radially. Thus when split-bolt 10 is inserted into an opening, the insertion of wedge 22 spaces segments 11 and 12 apart and brings thread sections 20 and 21, on segments 11 and 12, into contact with the interior of the threads on the inside of a coil insert.

Wedge 22 has a head portion 23, which extends above bolt heads 18 and 19 when it is inserted in a coil and a generally wedge-shaped tip 24. Tip 24, because of its wedge shape, is useful in combination with sloped interior surfaces 25 and 26 of segments 11 and 12 to initiate the separation of segments 11 and 12 so that wedge 22 can be fully inserted.

A longitudinal slot 30 is provided intermediate the head 23 and tip 24 of wedge 22, and a pin 31 interconnects segments 11 and 12 with wedge 22 via slot 30. Pin 31 passes through pin hole 32, in head 19 of segment 12, through slot 30, and is threaded into bore 33 in head 18 of segment 11. Longitudinal slot 30 allows wedge 22 to be extracted from between surfaces 13 and 14 to almost its full length and yet to remain connected via pin 31 to segments 11 and 12. Interconnecting the parts is not necessary, as it is merely a convenient means for keeping the parts of the split-bolt in close proximity.

As illustrated in the drawings, slot 30 can also be used as a convenient means for limiting the insertion of said insert or wedge member such that the head end thereof extends a predetermined longitudinal distance from the outer ends of said bolt segments. Alternatively, the limiting means could be part of or the entire bottom of the recess, e.g., the bottom of a coil insert, a portion of one or both of the inner faces of the segements, which would act like a stop, or the like.

A means for extracting wedge 22 from between segments 11 and 12 is provided on head 23. As shown in FIG. 1, the means consists of cylindrical bosses 35 and 36 on either side of wedge 22. While the bosses are shown being cylindrical, the invention is not limited to that particular geometry, since other shapes may be used, such as semi-cylinders, octagons, etc. Also, the bosses may be either integral with or separate from wedge 22. As shown in FIG. 1, separate cylindrical pieces 35 and 36 are attached to wedge 22 by pin 37. Other fasteners or fastening means may also be employed. Thus, bosses 35 and 36 on head 23 provide the means by which wedge 22 may be extracted. As long as the means for extracting is within the teachings of the invention disclosed, the invention is not limited to the means illustrated.

When it is desired to remove split-bolt 10 from an opening in which it is installed, wedge 22 can be extracted by grasping bosses 35 and 36. If wedge 22 is tightly bound by inner surfaces 13 and 14 of segments 11 and 12, a tool may be used to extract wedge 22.

FIG. 2 shows the use, as an example, of a claw hammer 40 to extract wedge 22 via bosses 35-36 on head 23. If wedge 22 cannot be extracted by merely exerting an upward (longitudinal or axial) force, bolt head sections 18 and 19 will provide a convenient fulcrum for applying a levered force to head 23.

As an example of use, split-bolt 10 might be employed in combination with coil inserts which are embedded in concrete slabs to attach lift rings to the slabs. FIG. 3 shows a coil insert 50 which might be employed in combination with split-bolt 10. Generally, coil insert 50 will consist of a coil 51 and a plurality of legs 52 which support the coil. Coil 51 may be formed of a plurality of closely spaced turns of heavy wire or rod. The turns may or may not be welded together, as desired.

Coil 51 will have an internal screw thread structure 53 which will accept threads, e.g., threads 20 and 21 (FIGS. 1 and 2) on split-bolt 10. Legs 52 consist of a vertical section 54 which is welded to the exterior of coil 51. The vertical portion 54 of each of the legs is joined by an irregularly shaped portion 55 which extends initially in a generally horizontal direction and has an open hook shape at end 56.

Legs 52 support coil 51 when insert 50 is being placed within a concrete form or mold. Hook-shaped ends 56 may be used to support and space reinforcing members (not shown) for reinforcing the cast concrete object. Boots 57 may be provided at the bottom of the hook-shaped portions 56 to prevent irregular shaped portions 55 of legs 52 from being exposed during the casting process and to prevent any rust from insert 50 from reaching the cast concrete surface. Boots 57 can be cylindrically shaped stainless steel pieces or can be made from other metal or plastic materials. Other boot structures may be employed to prevent exposing leg portions 55, and, further, to prevent the accumulation of rust on the cast concrete surface.

The coil insert usually will be cast below the surface of the concrete object. This is best illustrated in FIG. 4 where coil insert 50 is shown embedded inside concrete block 70. Generally, the coil insert is embedded a predetermined distance below the surface of the concrete object, for example, about two inches below the surface.

Means must be provided to prevent concrete from filling threaded interior 53 of coil insert 50 during the casting process. As shown in FIG. 3, plastic caps or plugs 58 and 59 may be used to exclude concrete from interior 53. Plug 59 will be below the surface of the cast concrete block 70, so flag 65 is provided to show the location of the plug. After casting the concrete object, plug 59 is located via flag 65 and removed. This can be done by chipping away the thin layer, concrete covering and prying the plug out to expose threaded interior 53 of coil insert 50.

Once the cast concrete object is set and interior threads 53 of insert 50 are exposed, a means for lifting, moving and installing the concrete object can be attached. FIGS. 4 and 5 illustrate the attachment of such a means generally, and specifically the attachment of a lifting ring 71 to concrete block 70.

Lifting ring 71 may take many and various forms, for example, hinged rings or eyes, or special attachments that are designed to cooperate with a particular type of hoisting means. As illustrated in FIGS. 4 and 5, lifting ring 71 consists of a flat rectangular shaped base 72 to which is attached a central boss member 73. The boss member 73 is provided with a central opening 64 having substantially the same diameter as the overall diameter of the bolt means. The boss member may be formed integrally with the base plate as by means of casting or may be formed separately and attached to the base plate by means of welding and the like. The boss 73 is provided with two outwardly extending horizontal pin members 74 and 76.

A lifting ring or eye 77, provided with bosses 78 and 79 at its lower end, is pivotally mounted on the pins 75 and 76. The lifting ring or eye 77 may be held in position by peening over the ends 80 and 81 of the pins 75 and 76. While the pins 75 and 76 are shown as being formed integrally with the boss member 73, it may be preferable to form the pins separately, and then to attach the lifting ring 77 to the boss by driving the ends of the pins into holes bored in the boss member. When a unitary structure is used for the boss and pins, it will be necessary to open the rings 77 so that the ends of the ring can be placed over the pins. The ring can then be closed to its original position.

In use, lifting ring 71 is positioned to align its central opening 74 with the threads 53 of coil 51. By withdrawing wedge 22 from between segments 11 and 12, surfaces 13 and 14 can be brought into contact. The "collapsed" bolt is then readily inserted into opening 74 and threads 53. When wedge 22 is inserted between segments 11 and 12, they are spaced apart, expanding radially, causing threads 20 and 21 to engage threads 53. A slight twist of bolt 10 will tighten down lifting ring 71.

Once the concrete panel has been lifted, moved and installed, the lifting ring is removed. By grasping bosses 35 and 36 on head 23, wedge 22 can be extracted allowing segments 11 and 12 to be collapsed. Bolt 10 can then be readily withdrawn. If wedge 22 is bound tightly by segments 11 and 12, it can be grasped by a claw hammer to pull it free. After lifting ring 71 is removed, a hole remains which was created by removing plug 59, and it can be filled with concrete to create a smooth, continuous surface on the panel.

While the form of apparatus herein described constitutes a preferred embodiment of this invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention.

Claims

What is claimed is:

1. A bolt of the character described, comprising bolt segments which when brought together render said bolt readily insertable into a complementary threaded recess, which have outer surfaces threadably engageable with such recess when said segments are spaced apart and which have head portions, and an elongated wedge member insertable between said segments to space said segments into such threadable relation, said wedge member having a generally elongated rectangular shape and substantially flat major faces and having a head end, means limiting insertion of said wedge member between said segments to a position wherein said wedge head end extends a predetermined longitudinal distance from the outer ends of said bolt segments and said bolt head portions, and boss means on said head end of said wedge member and located on said flat major faces a predetermined longitudinal distance from said bolt head portions for grasping and removing said wedge member from between said segments, said boss means and said head portions of said bolt segments being arranged so that a lever means can be used to apply a force between said boss means and said head portions to remove said wedge member.

2. A bolt as in claim 1 wherein said boss means comprise substantially cylindrical bosses.

3. A bolt as in claim 1 wherein the other end of said wedge member is generally wedge-shaped to initiate the spacing of said segments upon insertion thereof between said segments.

4. A bolt as in claim 1 wherein said bosses are on said major faces, whereby said insert means can be extracted from between said bolt segments by hand or by using a tool.

5. A bolt as in claim 4 wherein said bosses are generally cylindrically shaped.