Patent Publication Number: US-6220069-B1

Title: Method and apparatus for bending tubing

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to bend dies, and more particularly, to bend dies which produce multiple bends within tubing. 
     Tubing often is used to carry pressurized fluids from one location to another. The tubing is installed after assembly of major components and must be routed around obstructions to complete a fluid circuit. Such routing may require compound bends in the tubing. 
     Typically, compound bends are formed using manual or automated bending machines. To form compound bends, the tubing often must be located in multiple pre-bending tubing positions to securely position the tubing while the tubing is bent. Multiple clamps are used to hold the tubing in place. However, a straight section of tubing between clamps typically is required to form the desired bends. The straight section length is typically a minimum of two to three times a diameter of the tubing. 
     To form a compound bend having bends closer together than possible with known manual or automated bending machines, a portion of the desired bends is formed on several pieces of tubing. The separate pieces are then welded together to form a single tube having the desired compound bends. Alternatively, a first portion of the compound bend is formed using a bending machine and a first clamp block, and a second clamp block is manufactured to include a second portion of the desired compound bend and used with the bending machine to form a second portion of the compound bend. The process is repeated with as many clamp blocks as necessary until the desired compound bend is formed in a single piece of tubing. 
     Welding multiple sections of tubing together to form a single tubing having the desired compound bends, produces tubing that does not have the structural integrity of non-welded tubing. Creating a compound bend using multiple clamp blocks forms a compound bend in tubing that maintains the structural integrity of non-welded tubing, but is much more laborious and cumbersome to form. Multiple assembly set-ups and clamp block manufacturing increases the time necessary to form a desired compound bend in tubing. 
     BRIEF SUMMARY OF THE INVENTION 
     In an exemplary embodiment, a bend die assembly facilitates the formation of a compound bend in a single tube in a single operation. The assembly includes a bend die, a base, and a clamp block assembly. The bend die is attached to the base and includes a t-shaped projection which extends outward from the bend die. The clamp block assembly includes a first clamp block and a second clamp block. The first clamp block includes a first opening, a plurality of second openings, and a plurality of projections. The first opening is substantially T-shaped and slidably receives the bend die projection. The plurality of second openings are disposed in a bottom surface of the first clamp block and engage a plurality of clamp block drive keys attached to the base. The first clamp block also includes a tube groove which includes a plurality of indentations which in combination with the second clamp block produce a desired compound bend in tubing. 
     In operation, the first clamp block is easily installed or removed from the bend die. Additionally, the first clamp block and the second clamp block each include a tube groove which mate together to hold and position the tube as the bend die forms the desired compound bend in one operation. Because all bending is accomplished with the use of the bend die and the clamp block assembly, no pre-bend setup steps are necessary. Furthermore, because no additional clamps are used to position the tubing, a straight length of tubing is not necessary between bends in the compound bend. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded top perspective view of a bend die assembly; and 
     FIG. 2 is an exploded bottom perspective view of the bend die assembly shown in FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is an exploded top perspective view of a bend die assembly  10  for use with a bending machine (not shown) in bending tubing  12 . Bend die assembly  10  includes a base  14 , a bend die  16 , a first clamp block  18 , and a second clamp block  20 . Base  14  includes a first side  22 , and a second side  24  attached to first side  22  with a third side  26  and a fourth side  28 . A first groove  40  extends from third side  26  towards fourth side  28  to a center opening  42 . Center opening  42  extends from a base top surface  44  to a base bottom surface (not shown in FIG.  1 ). A second groove  46  extends from first side  22  through center opening  42  to second side  24 . A third groove  48  extends from fourth side  28  to center opening  42 . Grooves  40 ,  46 , and  48  have a depth  50  which extends from base top surface  44  towards the base bottom surface. Depth  50  is less than a thickness  54  of base  14 . 
     Grooves  40 ,  46 , and  48  are sized to receive a bend die locator  60  when bend die assembly  10  is fully assembled. Bend die locator  60  is positioned between base  14  and bend die  16  and includes a first leg  62 , a second leg  64 , and a third leg  66 , each extending radially outward from a center ring  68 . Ring  68  includes an opening  70  which is positioned substantially concentrically with base center opening  42 . Bend die locator  60  has a thickness  71  extending between a locator top surface  72  and a locator bottom surface (not shown) which is uniform throughout bend die locator  60 . Thickness  71  is greater than depth  50  and as such, when bend die locator  60  is attached to base  14 , top surface  72  extends from base top surface  44  and engages bend die  16 . 
     Bend die  16  includes a top portion  80 , a bottom portion  82 , a body portion  84  extending between top portion  80  and bottom portion  82 , and a top outer edge  85 . Bend die  16  also includes a front wall  86  and a rear wall  88 . Rear wall  88  extends from front wall  86  such that top portion  80  and bottom portion  82  have planar semi-circular cross sectional profiles (not shown). 
     Top portion  80  includes a top surface  90  and a keyway  92 . Top surface  90  extends between front wall  86  and rear wall  88 . Keyway  92  includes a first groove  100 , a second groove  102 , and a third groove  104 . Grooves  100 ,  102 , and  104  extend radially outward from an annular shoulder  106  to top outer edge  85  of bend die  16 . Additionally, grooves  100 ,  102 , and  104  are sized to receive bend die locator legs  62 ,  64 , and  66 . Annular shoulder  106  extends circumferentially from a center opening  108 . Center opening  108  extends through bend die  16  from top portion top surface  90  through body portion  84  and through bottom portion  82 . 
     Bend die bottom portion  82  is constructed substantially identically to bend die top portion  80  and includes a keyway  110  constructed identically to keyway  92 . Keyway  110  includes a first groove  112 , a second groove (not shown in FIG.  1 ), and a third groove (not shown in FIG. 1) extending radially outward from center opening  108  through a bottom surface (not shown in FIG. 1) of bend die  16 . Keyways  110  and  92  are sized such that when bend die  16  is attached to bend die locator  60 , bend die locator legs  62 ,  64 , and  66  are received in keyway  92  or  110 . Legs  62 ,  64 , and  66  ensure bend die  16  is aligned and during a bending operation, legs  62 ,  64 , and  66  transfer loading induced into bend die  16  from the bending machine into base  14 . In one embodiment, when bend die  16  is attached to bend die locator  60 , bend die bottom portion keyway  110  engages legs  62 ,  64 , and  66 . Alternatively, bend die  16  is attached to bend die locator  60  such that bend die top portion keyway  92  engages legs  62 ,  64 , and  66 . 
     Body portion  84  includes a tube groove  120  circumscribing bend die top outer edge  85  along rear wall  88 . Tube groove  120  is substantially semi-circular and is sized to receive tubing  12 . Tube groove  120  extends approximately  180  degrees along rear wall  88  to front wall  86  such that adjacent front wall  86 , a first side  122  of tube grove  120  is substantially parallel to a second side  124  of tube groove  120 . 
     A projection  130  extends outward from bend die front wall  86  a distance  132 . Projection  130  is substantially T-shaped and has a first portion  134  and a second portion  136  extending from first portion  134 . Second portion  136  has a width  137  extending from a first side wall  138  to a second side wall (not shown in FIG.  1 ). Projection  130  is positioned between tube groove first side  122  and tube groove second side  124 . Additionally, projection  130  is continuous and extends from the bend die bottom surface to bend die top surface  90 . 
     A locator cap  140  is attached to bend die  16 . During a bending operation, locator cap  140  rotates simultaneously with bend die  16  and indicates an amount of bending that has been applied to tubing  12 . Locator cap  140  includes a center opening  142 , a top surface  144 , and a bottom surface (not shown in FIG.  1 ). When locator cap  140  is attached to bend die  16 , center-opening  142  is substantially concentric with center opening  108  such that when bend die assembly  10  is fully assembled, a bolt (not shown) extends through openings  42 ,  70 ,  108 , and  142  and is secured with a nut (not shown) which secures bend die assembly  10  together. 
     A projection  146  extends from the bottom surface of locator cap  140 . Projection  146  engages keyway annular shoulder  106  when locator cap  140  is attached to bend die  16 . In one embodiment, locator cap  140  is attached to bend die  16  such that the bottom surface of locator cap  140  contacts bend die top surface  90 . Alternatively, depending on the installation of bend die  16 , locator cap  140  may be installed such that the bottom surface of locator cap  140  contacts bend die bottom surface. 
     First clamp block  18  includes an opening  150  which has a width  151 . Opening  150  is substantially T-shaped and includes a first opening portion  152  and a second opening portion  153 . Second opening portion  153  has a width approximately equal to width  137  of bend die projection second portion  136 . As such, opening  150  is sized to slidably receive bend die projection  130  to create an interfit (not shown) between projection  130  and opening  150 . The interfit connection secures first clamp block  18  to bend die  16  such that during a bending operation, first clamp block  18  cannot rotate independently of bend die  16 . Additionally, the interfit permits clamp block  18  to be easily removed from bend die  16  when a different clamp block (not shown) is being installed. 
     Opening  150  is disposed within a front surface (not shown in FIG. 1) of first clamp block  18  and extends from a top surface  154  of first clamp block  18  to a bottom surface (not shown in FIG. 1) of first clamp block  18 . A distance (not shown in FIG. 1) between top surface  154  and the bottom surface of first clamp block  18  is substantially equal to a distance  160  extending between bend die top surface  90  and the bend die bottom surface. First clamp block  18  also includes a plurality of guide pins  162  and a channel opening (not shown in FIG.  1 ). Guide pins  162  extend outward from a first side (not shown in FIG. 1) of first clamp block  18  and during a bending operation, engage second clamp block  20 . The channel opening is disposed in the bottom surface of first clamp block  18  and are sized to receive a pair of clamp block drive keys  170  and  172 . 
     Clamp block drive keys  170  and  172  are constructed identically and each includes a screw  174  and a channel block  176 . Each channel block  176  has a width  178  approximately equal to a width  180  of base first groove  40 . Additionally, each channel block has a thickness  182  larger than first groove depth  50 . As such, each channel block  176  is slidably received in first groove  40 . Furthermore, each channel block  176  includes an opening  184  sized to receive screw  174  which secures channel block  176  in place on bend die assembly base  14 . Channel block  176  is counterbored such that when screw  174  is fully inserted within channel block  176 , a head portion  188  is fully inserted within channel block  176 . When first clamp block  18  is attached to bend die  16 , channel block  176  engages the openings disposed in the bottom surface of first clamp block  18 . During a bending operation, the combination of the interfit between first clamp block  18  and bend die  16  and the interaction between channel blocks  176  and clamp block  18 , transfers loads induced by the bending machine into bend die assembly base  14 . 
     First clamp block  18  also includes a tube groove  190 . Tube groove  190  is semi-circular in shape and is positioned such that when first clamp block  18  is fully attached to bend die  16 , a first end (not shown) of tube groove  190  adjacent top surface  154  is substantially co-planar and aligned with bend die tube groove  120 . In one embodiment, the first end of tube groove  190  is aligned with second side  124  of tube groove  120 . Alternatively, depending on the installation of bend die  16 , the first end of tube groove  190  is aligned with first side  122  of bend die tube groove  120 . Tube groove  190  includes a plurality of indentations (not shown) which engage tubing  12  during a bending operation. 
     Second clamp block  20  is attached to the bending machine. A plurality of openings  199  are disposed in a side wall  200  of second clamp block  20  and are sized to receive a plurality of guide pins  162  extending from first clamp block  18 . Side wall  200  also includes a tube groove  202  semi-circular in shape and shaped to align and mate with tube groove  190  of first clamp block  18 . As such, tube groove  202  includes a plurality of indentations (not shown in FIG.  1 ), which correspond to the indentations within tube groove  190 . 
     In operation, base  14  is positioned in close proximity to the bending machine and bend die locator  60  is attached to base  14  such that bend die locator legs  62 ,  64 , and  66  engage base grooves  40 ,  46 , and  48 . Bend die  16  is attached to bend die locator  60  such that either bend die top surface  90  or the bend die bottom surface is in contact with bend die locator  60 . Locator cap  140  is attached to bend die  16  and a first clamp block, i.e.  18 , and a mating second clamp block, i.e.  20 , are selected which include the tube groove indentations which will engage desired bends  196  in tubing  12 . Clamp block drive keys  170  and  172  are installed within base groove  40  and the first clamp block is slidably attached to bend die  16  such that an interfit is created between bend die T-shaped projection  130  and the corresponding T-shaped opening, i.e.,  150  of the first clamp block, and such that the first clamp block engages clamp block drive keys  170  and  172 . Tubing  12  is positioned within bend die tube groove  120  and within a tube groove, i.e.  190 , disposed within the first clamp block selected. The mating second clamp block is attached to the bending machine, and during operation is forced against tubing  12  to secure tubing  12  between the clamp blocks selected such that the bending machine may produce bends  196  within tubing  12  with bend die  16 . 
     FIG. 2 is an exploded bottom perspective view of bend die assembly  10  including base  14 , bend die  16 , first clamp block  18 , and second clamp block  20 . Base  14  includes center opening  42  and a plurality of openings  210 . Center opening  42  extends from base top surface  44  to a base bottom surface  212  and is sized to receive a bolt used to secure bend die  16  and locator cap  140  to base  14 . Openings  210  are disposed within base first groove  40  (shown in FIG. 1) and extend from base top surface  44  to base bottom surface  212 . Openings  210  are sized to receive clamp block drive key screws  174  to secure clamp block drive keys  170  and  172  to base  14 . Base bottom surface  212  includes a groove  214  which extends from base third side  26  to an indentation  216 . Indentation  216  circumferentially surrounds center opening  42  and has a depth  220  which is less than base thickness  54  and is uniform throughout groove  214  and indentation  216 . Groove  214  and indentation  216  are sized to mount to a bending machine (not shown). 
     Bend die  16  includes bottom portion  82 , top portion  80  (shown in FIG.  1 ), and projection  130 . Bottom portion  82  is constructed substantially identically to top portion  80  and includes keyway  110 . Keyway  110  includes first groove  112 , a second groove  230 , and a third groove  232 . Grooves  112 ,  230 , and  232  extend radially outward from an annular shoulder  234  to a bottom outer edge  235  of bend die  16 . Additionally, grooves  112 ,  230 , and  232  are sized to receive bend die locator legs  62 ,  64 , and  66 . Annular shoulder  234  extends circumferentially from center opening  108  and has a depth  236  extending inward from a bottom surface  238 . Bend die projection  130  extends outward from bend die front wall  86  (shown in FIG. 1) and includes first side wall  138  and a second side wall  240 . Projection  130  is positioned between tube groove first side  122  (shown in FIG. 1) and tube groove second side  124 . 
     Locator cap  140  includes center opening  142 , top surface  144  (shown in FIG.  1 ), and a bottom surface  242 . Bottom surface  242  includes a projection  244  which circumferentially surrounds center opening  142  and extends from bottom surface  242  a distance  246 . Projection  244  is sized to fit within bend die keyway  92  (shown in FIG. 1) or bend die keyway  110  when locator cap  140  is attached to bend die  16 . 
     First clamp block  18  includes opening  150  sized to receive bend die projection  130  and is disposed within a front surface  250  of first clamp block  18 . First clamp block top surface  154  (shown in FIG. 1) is a distance  252  from a first clamp block bottom surface  254 . Distance  252  is substantially equal to a distance  160  (shown in FIG. 1) extending between bend die top surface  90  (shown in FIG. 1) and bend die bottom surface  238 . First clamp block  18  also includes guide pins  162  and a channel opening  255 . Channel opening  255  extends a distance  260  inward from first clamp block bottom surface  254  and is sized to receive clamp block drive keys  170  and  172 . Guide pins  162  extend from a first side  264  of first clamp block  18  and during a bending operation engage second clamp block  20 . 
     Second clamp block  20  includes openings  199  sized to receive guide pins  162 . Additionally, second clamp block  20  includes tube groove  202 . Tube groove  202  is sized to receive tubing  12  and includes a plurality of indentations  266  which correspond to indentations (not shown) within first clamp block tube groove  190 . 
     The above-described bend die assembly is cost-effective and highly reliable. The bend die assembly is easily assembled and includes components which are reversible and increase the option available to a user. The components are slidably attached and are quickly interchanged. As a result, a bend die assembly is provided which permits the formation of a compound bend in a single tube in a single operation. Thus, a structurally sound tube is produced without a laborious and time-consuming operation. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.