You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND OF THE INVENTION 
     This invention relates in general to anchor bolt forms and deals more particularly with improved pipe sleeves for anchor bolts and the like. 
     A typical pipe sleeve of the type commonly used in the construction industry to form a void around an anchor bolt embedded in concrete comprises a length of cylindrical pipe which has a plate tack welded across its lower end. An anchor bolt is inserted upwardly through a pre-drilled or punched hole in the plate and through the sleeve. The pipe sleeve is then secured to the bolt in a predetermined axial position by tack welding the plate to the shank of the bolt. The sleeve is open at its upper end, however, it is customary to stuff the open end with waste to prevent foreign material and moisture from entering the void formed by the sleeve until such time as the void is filled with concrete or other suitable material. 
     While pipe sleeves of the aforedescribed general type have gained wide acceptance in the construction industry, there are recognized disadvantages in the use of such sleeve structures. Apart from the relatively high cost of materials, skilled labor is needed to perform the necessary welding operations to fabricate such sleeves and assemble the sleeves with bolts. If welding equipment is not available at the construction site, sleeves must be assembled with anchor bolts elsewhere and transported to the job site in assembled condition which introduces problems in transportation and handling. After a pipe sleeve has been welded into assembly with a bolt, it can no longer be adjusted relative to the bolt to compensate for an unexpected condition encountered when the assembly is put in position at the job site. Further, the practice of stuffing the open ends of pipe sleeves to prevent contamination is generally recognized as an unsatisfactory solution to the problem. If the sleeve openings are not stuffed, or if the stuffing material becomes dislodged, the voids are likely to become contaminated with foreign material or moisture which must be removed before finishing operations can be completed. 
     It is the general aim of the present invention to provide improved pipe sleeves for anchor bolts which may be readily assembled on bolts by persons of ordinary skill and without special tools or equipment. It is the further aim of the invention to provide improved pipe sleeves which may be readily adjusted relative to bolts to compensate for variations in job site conditions and which positively prevent void contamination. A still further aim of the invention is to provide a pipe sleeve adapter assembly for use with standard pipe to form an adjustable anchor bolt sleeve. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, an improved adjustable sleeve for an anchor bolt is provided which comprises a length of cylindrical pipe for receiving the bolt therethrough and an adapter assembly which includes an outer part for threadable connection with the upper end of the pipe and an inner part for threadable engagement with the upper end of the bolt. The inner and outer parts have co-engageable bearing surfaces which cooperate to maintain the pipe sleeve in coaxial alignment with the bolt and support it in predetermined axial position relative to the bolt. The inner and outer parts further cooperate to provide a closure for the upper end of the pipe and are readily removable to expose the void within the pipe. After the adapter assembly has been removed from the pipe, it may be used with another length of pipe to form another pipe sleeve. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary side elevational view of a pipe sleeve embodying the present invention shown mounted on an anchor bolt and partially in vertical axial section. 
     FIG. 2 is a sectional view taken along the line 2--2 of FIG. 1. 
     FIG. 3 is similar to FIG. 1, but shows another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings, an anchor bolt form or a pipe sleeve embodying the present invention and indicated generally by the reference numeral 10 in FIGS. 1 and 2 is shown mounted on an anchor bolt designated generally by the numeral 12. The illustrated bolt 12, shown oriented in an axially vertical position, has an elongated shank 14 and a threaded upper end portion indicated at 16. The lower end of the bolt may be of any suitable configuration, however, the illustrated bolt 12 is threaded at its lower end to receive a nut. 
     The pipe sleeve 10 generally comprises a length of cylindrical pipe 18 which has an internal thread 19 at its upper end and an adapter assembly 20 for threadable connection to the upper end of the pipe and to the anchor bolt 12 to support the pipe 18 in depending position on the bolt and to maintain it in generally coaxial alignment with the bolt. Preferably, and as shown, the pipe sleeve 10 also includes a bottom member or plate 22 which provides a closure for the lower end of the pipe 18. The plate 22 is welded or otherwise attached to the lower end of the pipe 18 and has a central hole 23 for receiving the bolt shank 14 therethrough. The diameter of the hole 23 is substantially equal to or slightly larger than the diameter of the bolt shank so that the bolt shank may pass freely therethrough. 
     The adapter assembly 20 may be made from any suitable material, but preferably and as shown, it is molded from plastic and comprises an outer part or ring member 24 and an inner part or nut member 26. The ring member 24 has a thread 25 on its annular peripheral surface for engaging the thread 19. A stepped bore extends coaxially through the ring member 24 and defines a plurality of bearing surfaces which include radially inwardly facing bearing surfaces 30 and 32, respectively, defined by the lower and upper portions of the bore and an axially downwardly facing bearing surface 34 intermediate the upper and lower portions. The nut member 26 comprises a generally cylindrical nut threaded for engagement with the upper end of the bolt 12. The annular peripheral surfaces of the nut 26 generally complement the surfaces of the bore 29. More specifically, the nut 26 has generally radially outwardly facing annular bearing surfaces 36 and 38 for complementary engagement with the inwardly facing bearing surfaces 30 and 32. The nut 26 further defines a generally axially upwardly facing bearing surface 40 which substantially complements the downwardly facing bearing surface 34 on the ring member. When the nut member 26 is assembled with the bolt 12 and the ring member 24 is connected to the pipe 18, the co-engageable bearing surfaces on the two members 24 and 26 co-operate to maintain the pipe 18 in coaxial alignment with the bolt 12. 
     In assemblying the pipe sleeve 10 with the bolt 12, the bolt is inserted upwardly through the hole 23 and through the pipe 18. Thereafter, the nut member 26 is then threaded onto the upper end of the bolt 12 to an approximate position of adjustment. The ring member 24 is then threaded into the upper end of the pipe 18 until the upper surface of the ring member is substantially disposed within the plane of the upper end of the pipe. It should be noted that when the pipe sleeve 10 is assembled with the bolt 12 the ring member 24 and the nut member 26 cooperate to provide a closure or the upper end of the pipe 18. Further, the upper surface of the ring member and the nut member lie substantially within the plane of the upper end of the pipe to provide a substantially planar surface. In the assembled condition, shown in FIG. 1, the upper end of the nut member 26 is accessible externally of the pipe 18 so that the nut member 26 may be rotated in one or in an opposite direction relative to the bolt 12 to adjust the angular positioning of the sleeve 10 relative to the bolt. 
     After the bolt 12 and the pipe sleeve 10 have been embedded in a concrete foundation or the like, the adapter assembly 20 may be removed to expose the void around the bolt. The ring member 24 is first threaded out of engagement with the pipe 18. Thereafter, the nut member may be threaded out of engagement with the bolt 12. The adapter assembly 20 may then be used with another length of pipe and another bolt to form another pipe sleeve assembly. 
     The present invention may be practiced with a standard pipe which is either internally or externally threaded at its upper end. Referring now to FIG. 3 another pipe sleeve embodying the present invention and indicated generally by the reference numeral 10a is shown connected to an anchor bolt 12a which has an L-shaped head at its lower end to provide a firm footing in a concrete foundation or the like. The sleeve 10a includes an axially elongated length of pipe designated 18a which has an external thread at its upper end. The pipe sleeve 10a further includes an adapter assembly 20a substantially identical to the adapter assembly 20 previously described. A threaded coupling member which comprises a standard pipe coupling 44 is used to connect the adapter assembly 20a to the upper end of the pipe 18a, substantially as shown. Thus, the same adapter assembly may be utilized with either type of pipe. 
     The pipe assembly 10a also has a bottom member of plug 22a which provides a closure for the lower end of the pipe. The plug 22a is adapted for force fit engagement within the lower end of the pipe 18a. Preferably, and as shown, it is molded from plastic material and has a central hole 23a for receiving the bolt 12a therethrough. The annular peripheral surface of the plug 22a designated by the numeral 46 is or may be slightly tapered to facilitate forceable assembly within the lower end of the pipe.

Summary:
An adjustable pipe sleeve for an anchor bolt comprises a length of cylindrical pipe supported in depending position on an anchor bolt by an adapter assembly which includes one part threaded onto an upper end portion of the bolt and another part threadably engaged with the upper end of the pipe. Coengagable bearing surfaces on the parts cooperate to maintain the pipe in an adjusted axial position and in coaxial alignment with the bolt.