Abstract:
The specification discloses a spacer for use with first and second wire reinforcing fabrics to space the first and second fabrics one from the other during the manufacture of wire reinforced concrete articles. The spacer includes a spacing member, first and second camming members extending from the spacing member in a generally common direction to cammingly engage the fabrics, and first and second locking portions operatively extending from the first and second camming members, respectively, to aid in positioning and securing the spacer on the fabrics. An assembly incorporating the spacer and a method of using the spacer are also disclosed.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a spacer for wire reinforcement used in the manufacture of welded wire reinforced concrete articles such as pipe, and more specifically to a spacer for maintaining concentric wire reinforcement cages in spaced relationship from each other and the pipe form when concrete is formed around the wire reinforcement. 
     A wire reinforcing assembly typically comprises wire fabric formed to generally conform to the shape of the article being produced. For example, in manufacturing a wire reinforced concrete pipe, the fabric is shaped into a generally cylindrical cage having a smaller diameter than the outer cylindrical pipe form in which the pipe is to be cast. Often, a second cylindrical cage having a diameter somewhat smaller than that of the first cylindrical cage is included to further reinforce the concrete pipe. 
     In the manufacture of a wire reinforced concrete pipe, it is important that the cage assembly be located in the pipe form a spaced distance from the pipe form wall or walls. When a single external wall form is used and the pipe is dry cast in a packer head machine, the cage assembly must be spaced from the external wall. When a double wall form is utilized and the concrete is to be cast around the cage assembly, the assembly must be spaced from both the inner and outer walls. Further, to insure the structural integrity of the pipe, it is important that the two cylindrical cages in the assembly be maintained in fixed concentric relationship with respect to each other during manufacture. Various spacing devices exist in the prior art for performing these spacing functions, but none is completely satisfactory. 
     Often, the two concentric cages are tied with wire ties to common spacer bars oriented generally radially with respect to the cages. These spacer bars extend radially outwardly beyond the outer cage and/or radially inwardly beyond the inner cage to engage the pipe form to maintain the cage assembly in proper spaced orientation within the form during casting. Alternatively, the spacer bars can be welded to the cylindrical cages. In any event, the attachment of these spacer bars to the cages is extremely time consuming, whether they are tied using wire ties or welded. Additionally, the unfinished rod ends which engage the pipe form to space the assembly from the form may scratch, or score, the form destroying its smooth surface. Further, these rods can be bent when the cage assembly is inserted into the form or during subsequent casting, which destroys the desired accurate spacing between the cage and the pipe form. 
     Another spacer for maintaining cylindrical cages in concentric relationship includes an elongated spacer member having a J-hook at one end and a C-hook at an opposite end. (U.S. Pat. No. 3,440,792 to Schmidgall which issued Apr. 29, 1969) The J-hook is looped around a wire of one cage while the C-hook is cammed onto a wire of the second cage. A portion of the C-hook extends beyond the second cage to engage the pipe form. However, because the spacers include no locking structure at either one end, they do not positively retain the inner and outer cages in fixed relation. Further, because the spacer includes structure at only one end of the elongated member for spacing the cage assembly from the form, these spacers must be carefully alternated in orientation on the inner and outer cages to provide proper spacing within the pipe form. 
     Yet another spacer includes a bent metal member having first and second flanges extending from opposite sides thereof. The flanges are welded to inner and outer cages in order to properly maintain the inner and outer cages in proper orientation with respect to each other. The required welding is extremely time consuming and expensive. Further, these spacers do not include any provision for spacing the assembly from either of the form walls. Therefore, either the cage assembly is not properly oriented within the form or additional spacing means must be installed on the assembly in order to properly orient the assembly within the form. 
     SUMMARY OF THE INVENTION 
     The aforementioned problems are solved by the present invention wherein a cage spacer is provided including a spacing member having first and second ends, and first and second mounting structure operably connected to the first and second ends, respectively, for mounting and locking the spacer on the inner and outer cages. A plurality of spacers are mounted about the concentric cages to maintain the cages in spaced relationship with respect to one another during casting. In a preferred embodiment, the first and second mounting structure include first and second camming structure, respectively, for camming the spacer into engagement with the concentric cages. 
     Because the spacer of the present invention provides mounting, or camming, structure for securing the spacer to both the inner and outer cages, the spacer is positively secured on the cages to maintain them in fixed, concentric relationship. Further, the spacer may be readily installed on a cage assembly because it is simply cammed into position on both the inner and outer cages. No subsequent operations are required such as welding or wire typing to maintain the spacer on the cages. 
     In another preferred embodiment, an integral spacer portion extends from at least one of the first and second mounting structure to space the cage assembly from one or both of the inner and outer form walls. This embodiment eliminates the need for separate spacer members to space the cage assembly from the form. 
    
    
     These and other objects, advantages, and features of the invention will be more readily understood and appreciated by reference to the written specification and appended drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a wire reinforcing cage with reinforcement spacers constructed in accordance with the present invention installed thereon inserted within a concrete form having inner and outer walls; 
     FIG. 2 is a perspective view of one spacer mounted on the wire fabric; 
     FIG. 3 is a view taken along plane III--III in FIG. 2; 
     FIG. 4 is a view taken along plane IV--IV in FIG. 2; 
     FIG. 5 is a view similar to FIG. 2 showing the spacer only partially installed on the wire fabric; 
     FIG. 6 is a sectional view of a wire reinforcing cage with alternative embodiment reinforcement spacers installed thereon inserted within a concrete form having a single outer wall; 
     FIG. 7 is a perspective view of one alternative spacer mounted on the wire fabric; 
     FIG. 8 is a view taken along plane VIII--VIII in FIG. 7; 
     FIG. 9 is a view taken along plane IX--IX in FIG. 7; and 
     FIG. 10 is a view similar to FIG. 7 showing the spacer only partially installed on the wire fabric. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1, a plurality of spacers 10 are shown utilized in a conventional environment for constructing a reinforced concrete pipe. Outer form halves 12a and 12b are joined together to define outer form 12. Likewise, inner form halves 14a and 14b are connected to form inner form 14. Both outer form 12 and inner form 14 are generally circular in cross section and oriented generally concentrically. When this double wall type form is used, the concrete is cast, or poured, between forms 12 and 14 to fabricate the concrete pipe. Cage or fabric assembly 16 is mounted between forms 12 and 14. Consequently, when the concrete is cast between forms 12 and 14, the concrete and cage assembly 16 together form a reiforced concrete pipe. Such a pipe is later removed from the form by separating outer form halves 12a and 12b and withdrawing inner form 14 from the interior of the cast pipe. 
     Cage assembly 16 (FIG. 1) generally comprises inner cage 18, outer cage 20, and spacers 10 interconnecting the two cages. Inner cage 18 is formed by forming wire fabric comprised of longitudinal, or transverse, wires 22 and circumferential wires 24 into a cylindrical configuration. Similarly, outer cage 20 is formed by forming wire fabric comprised of longitudinal or transverse wires 26 and circumferential wires 28 into a similar cylindrical configuration. As shown, longitudinals 22 and 26 are on the outside of circumferentials 24 and 28, respectively, but it is understood that spacer 10 of the present invention works equally well if longitudinals 22 and 26 are on the inside of the circumferentials. Spacers 10 are typically mounted on the circumferentials 24 and 28 of cages 18 and 20 at spaced points around and along the length of the cages. 
     Each spacer 10 (FIGS. 3 and 4) is fabricated from low carbon, cold drawn steel and comprises a bar 30 which serves to space inner cage 18 from outer cage 20. Extending in a generally common lateral direction from bar 30 are camming members or portions 32a and 32b. Extending generally oppositely from camming portions 32a and 32b, respectively, are spacing portions 34a and 34b. Then extending generally towards one another from spacing portions 34a and 34b are wire-engaging (or positioning or locking) portions 36a and 36b. When spacers 10 are mounted on cage assembly 16 (FIG. 1), camming portions 32a and 32b and locking portions 36a and 36b cooperate to cause spacer 10 to be securely clipped to assembly 16. Further, spacing portions 34a and 34b engage inner and outer forms 14 and 12, respectively, to maintain assembly 16 in the proper position within the form. 
     As shown in FIGS. 1, 2, 3, and 4, spacers 10 are positioned on longitudinal wires 22 and 26 of the inner and outer cages. When so positioned, camming portions 32a and 32b cammingly engage circumferentials 24 and 28, respectively, and locking portions 36a and 36b extend around these longitudinals. Spacers 20 may alternatively be mounted on longitudinals 22 and 26 just as easily if the longitudinals happen to be located generally opposite one another when the cages are positioned one within the other. However, spacer 10 will be described as mounted only on circumferentials with the description being equally applicable when spacer 10 is mounted on longitudinals, since the circumferentials will always be generally opposite one another. 
     Cage spacer 10, as shown in FIGS. 2, 3, and 4, is made of a single piece of wire shaped to form bar 30, with bar ends 38a and 38b, camming members 32, spacing portions 34 and positioning portions 36. The length of generally linear bar 30 is selected to conform with the desired spacing between inner cage 18 and outer cage 20 in the concrete pipe. This spacing will vary with the diameter of the pipe, the thickness of the pipe wall, and the desired strength, among other considerations. 
     Camming members 32a and 32b extend from bar 30 at bar ends 38a and 38b, respectively. Camming members 32 extend in a generally common lateral direction, for example, as shown in FIG. 4, downwardly. Camming members 32a and 32b extend slightly inwardly toward each other to define pockets 40a and 40b, respectively, and then outwardly away from each other to define camming lobes 42a and 42b, respectively. When spacer 10 is properly mounted on cage assembly 16, circumferentials 24 and 28 are secured within pockets 40a and 40b. 
     U-shaped spacing portions 34a and 34b extend from camming lobes 42a and 42b, respectively. Lower legs 44a and 44b of spacing portions 34 are generally parallel to bar 30. Form-engaging bights 46a and 46b extend from lower legs 44 and continue into upper legs 48a and 48b, which are also generally parallel to bar 30 and engage circumferentials 24 and 28 when spacer 10 is mounted on assembly 16. 
     Locking portions 36a and 36b extend about opposite sides of circumferentials 24 and 28, respectively, to aid in preventing spacer 10 from shifting transversely of, or with respect to, the circumferentials. Indeed locking portions 36a and 36b help prevent cages 18 and 20 from shifting toward or away from one another. Portions 36a and 36b include bights 50a and 50b, which extend from upper legs 48a and 48b around circumferentials 24 and 28 and positioning legs 52a and 52b, which are opposite upper legs 48a and 48b. Positioning legs 52a and 52b are laterally offset from bar 30, permitting the circumferentials to be positioned therebetween during installation as will be described. Bights 50 are located generally opposite pockets 40. 
     OPERATION 
     Spacer 10 is mounted on cage assembly 16 by first abutting spacing portions 34a and 34b against circumferentials 24 and 28, respectively, as shown in FIG. 5. When so oriented, positioning portions 36 extend beyond a plane defined by circumferentials 24 and 28, and bar 30 is oriented at a nonperpendicular angle to circumferentials 24 and 28. Next, spacer portion 34b is slid along circumferential 28 toward longitudinal 26b and spacer portion 34a is slid along circumferential 24 toward longitudinal 22a until bar 30 is oriented generally perpendicularly to both circumferentials. At this point, circumferentials 24 and 28 are positioned between bar 30 and legs 52a and 52b, respectively; and camming lobes 42a and 42b abut the circumferentials. Spacer 10 is then rotated about an axis passing through positioning legs 52a and 52b so that camming lobes 42a and 42b cam onto circumferentials 24 and 28 until the circumferentials are positioned in pockets 40. 
     When so mounted, spacer 10 is securely retained on assembly 16. Circumferential 24 is secured within both pocket 40a and locking portion 36a; and circumferential 28 is secured within both pocket 40b and positioning portion 36b. Locking portions 36 prevent spacer 10 from being inadvertently knocked off the circumferentials. Preferably, each spacer 10 is located near a longitudinal wire which helps prevent spacer 10 from shifting along the length of the circumferential. Before assembly 16 is positioned within form 12, a plurality of spacers 10 are mounted along both the length and circumference of assembly 16 at strategic positions. Cage 16 is then inserted within form 12 so that each of form-engaging bights 46b engages interior surface 54 of outer form 12 and each of form-engaging bights 46a engage the exterior surface 56 of inner form 14. When assembled in this manner, assembly 16 is properly spaced from both forms 12 and 14. Further, inner and outer cages 18 and 20 are maintained in fixed relationship with respect to one another and with respect to forms 12 and 14. Finally, concrete is cast between forms 12 and 14 and around assembly 16 so as to form a section of concrete pipe. 
     ALTERNATIVE EMBODIMENT 
     An alternative embodiment 110 of the cage spacer is shown in FIGS. 6-10, wherein elements identical to elements in FIGS. 1-5 have numbers identical thereto preceded by a 1 (e.g., outer pipe form 112 in FIG. 6 corresponds to outer form 12 in FIG. 1). The major difference between alternative embodiment 110 and previous embodiment 10 is that spacing portion 34b is not included on the alternative embodiment. Consequently, lower arm 144b extending from camming lobe 142b extends into locking portion 136b rather than a spacing portion. Consequently, cage spacer 110 provides means for spacing assembly 116 from only an exterior form 112. 
     In FIG. 6, reference numeral 112 designates a single, external form utilized in construction of concrete pipe by use of a packer head machine. In the use of this single, form, the concrete is packed by the packer head on the inner surface 154 of form 112. Cage assembly 116 is mounted inside form 112 and spaced form inner surface 154 so that when the concrete is packed against inner surface 154, the concrete will be packed around assembly 116 so as to form a reinforced concrete pipe. Concentric inner and outer cages 118 and 120 are included to insure the structural integrity of the resulting pipe. The cured pipe is removed from form 112 by separating the form halves 112a and 112b. 
     Spacers 110 are shown positioned on circumferential wires 124 and 128 along both the circumference and length of assembly 116. As with the previously described embodiment, alternative spacers 110 can be mounted with equal applicability on longitudinals 122 and 126 if they are favorably located in the assembly. 
     Bar 130, camming member 132a, form-spacing portion 134a, and locking portion 136a of alternative spacer 110 are identical to their counterparts in previous spacer 10. Consequently, a detailed description of their structure and function is not necessary. 
     However, the structure extending from spacer bar 130 at bar end 138b is different from the corresponding structure in the previously described spacer 10. Camming member 132b extends from bar end 138b and extends first toward camming portion 132a to form pocket 140b and then away from camming portion 132a to define camming lobe 142b. Side arm 158a extends downwardly from camming lobe 142b. Lower leg 144b extends laterally from arm 158a, and side arm 158b extends upwardly from leg 144b. Side arms 158a and 158b are generally parallel to one another and perpendicular to lower leg 144b. Side arm 158b terminates in camming lobe 142c which engages circumferential 128 in the same fashion as its counterpart 142b. Spacer 110 then continues to define pocket 140c and extends around circumferential 128 to form upper leg 148b. Bight 150b extends from upper leg 148b around circumferential 128, terminating in positioning leg 152b positioned proximate circumferential 128 parallel to and opposite spacer bar 130. 
     Alternative spacer 110 is mounted on circumferentials 124 and 128 by first abutting spacing portion 134a against circumferential 128 and side arm 158b against circumferential 124 as shown in FIG. 10. In this position, both positioning legs 152a and 152b lie on the opposite side of a plane defined by the circumferentials from spacer bar 130. Next, locking portion 134b is slid along circumferential 128 toward longitudinal 126b and side arm 158b is slid along circumferential 124 toward longitudinal 122a until spacer bar 130 is generally perpendicular to both of the circumferentials. At this point, circumferentials 124 and 128 are positioned between upper legs 148 and positioning legs 152, and camming lobes 142a and 142c engage circumferentials 124 and 128, respectively. Alternative spacer 110 is then rotated about an axis extending through upper arms 148 so that camming lobes 142a, 142b, and 142c all cam onto the circumferentials so that circumferential 124 is positioned in pocket 140a and circumferential 128 is positioned in pockets 140b and 140c. 
     When so installed, alternative spacer 110 is securely retained on inner and outer cages 18 and 20. Camming members 132 prevent alternative spacer 110 from moving laterally with respect to the circumferentials, and locking portions 136 prevent alternative spacer 110 from moving radially to any significant extent with respect to the circumferentials. Before assembly 116 is mounted inside form 12, a plurality of spacers 110 are mounted along both the circumference and the length of the assembly at strategic positions. Assembly 116 is then inserted into form 112 so that each of spacing portions 134a engages interior surface 154 of form 112. When assembled in this manner, assembly 116 is properly spaced from form 112, and inner and outer cages 118 and 120 are maintained in fixed concentric relationship. Finally, a packer head (not shown) packs concrete around assembly 116 so as to form a section of concrete pipe. 
     It should be understood that the above description is intended to be that of preferred embodiments of the invention. For example, spacers 10 and 110 can be used to space flat sheets of fabric assemblies of tied or supported rod or rebar rod, the inner and outer reinforcements of a box culvert or like reinforcement means. In that regard, the term &#34;wire&#34; as used in the claims is also intended to encompass &#34;rod&#34;. 
     As shown in the drawings, locking portions 36 are shown as generally &#34;U&#34; shaped members. However, they could be more circular or arcuate in configuration. Manufacture might be facilitated with the more circular shape. The term &#34;generally U-shaped&#34; as used in the claims is intended to cover this variation as well. Also, the types of concrete forms used could vary, as well as methods for removing same. Instead of opening the inner and outer forms, overhead stripping techniques could be used. 
     Thus, various changes and alterations might be made without departing from the spirit and broader aspects of the invention as set forth in the appended claims, which are to be interpreted in accordance with the principles of patent law, including the doctrine of equivalents.