Abstract:
The present invention provides a internal pipe joints suitable for connection when pipes used under light-load conditions, or to be more concrete, plastic coated steel pipes having an external diameter ranging from about 28 mm to about 45 mm, which are produced by coating the outer surfaces of thin steel pipes with synthetic resin in a thin layer, are assembled into a planar or three-dimensional pipe structure, and more specifically, relates to pipe joints that have high strength in pipe connection and is excellent in design for having a simple appearance design in the position connecting the pipes. 
     The present invention comprises a joint body in which one or more connecting inset portions extending from the joint body and each inserted in an internal bore of a corresponding pipe to be connected are each formed to have a hollow structure, a plurality of long slit-like splits are formed in each of the connecting inset portions in a circumferential direction to axially extend from an end of the corresponding connecting inset portion, and the connecting inset portion is further provided in a hollow interior thereof with a tapered portion having an internal diameter decreasing from the end thereof toward the joint body; a tapered sleeve to be inserted in the hollow interior of the connecting inset portion; and a stop bolt having a conical portion in an end portion thereof.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates mainly to the technical field of internal pipe joints suitable for connection (or linking) when pipes used under light-load conditions, or to be more concrete, plastic coated steel pipes having an external diameter ranging from about 28 mm to about 45 mm, which are produced by coating the outer surfaces of thin steel pipes with synthetic resin in a thin layer, are assembled into a planar or three-dimensional pipe structure, and more specifically, relates to pipe joints that have high strength in pipe connection and is excellent in design for having a simple appearance design in the position connecting the pipes. 
         [0003]    2. Description of the Related Art 
         [0004]    As a joint for connecting pipes which assembles the pipes used under light-load conditions into a planar or three-dimensional pipe structure, an external joint in which a pipe is fitted to the socket of the joint has been conventionally known, for example, as disclosed in Japanese Design Registration No. 8811251 (hereinafter referred to as Patent Document 1). In this external joint, as seen in an enlarged sectional view in Patent Document 1, taken along line A-A′, the socket of the joint has a diameter larger than the external diameter of a pipe, and a long length of the socket is exposed. Steps produced by the different diameters of the socket and the pipes make the socket (joint) conspicuous, so that the appearance design of the pipe connection part is ungainly. Furthermore, due to a simple structure in which the pipes are merely fitted to the socket of the joint, it is difficult to physically and reliably increase the strength of connecting the pipes even if adhesive is used to tightly fit the pipes to the joint. Besides that, a stepped area between the joint and each pipe is liable to gather dust and is difficult to clean by cleansing. This causes the problem that the above-mentioned joint is not suitable for use in a pipe structure that is used in a situation, such as food industry, where sanitary regulations are strict. 
         [0005]    As disclosed in Japanese Unexamined Utility Model Publication No. 5-36114, in the case of an internal joint that is fitted to the internal bores of pipes, the joint in the pipe connection part is unnoticeable, which achieves a neat appearance design of the pipe connection part. However, due to a simple structure in which the pipes are merely fitted to the outer circumferences of the inset portions of the split joint, it is difficult to physically and reliably increase the strength of connecting the pipes even with adhesive. 
         [0006]    A pipe connector disclosed in Japanese Patent No. 2894404 is also one type of internal joints to be fitted to the internal bores of pipes. This pipe connector has a structure in which a chevron washer to be pressed against and firmly fixed to the inner surface of a pipe is operated by using a bolt and a nut. It is therefore surmised that the strength of connecting pipes can be physically and surely increased. On the other hand, the joint body must have through holes for a bolt-rotating tool to tighten bolts. These noticeable through holes spoil the design of the joint, that is, the appearance design of the pipe connection part, and they are prone to gather dust. In addition, even a firmly fastened bolt cannot dispel the concern that it may come loose and fall out in a long in-service period. 
       SUMMARY OF THE INVENTION 
       [0007]    As seen in Japanese Patent No. 2894404, there have conventionally been various types of joints that physically and surely increase the strength of connecting pipes by using bolts or the like. These joints, however, raise the concern that the bolts may come loose and fall out in a long in-service period. For example, a joint cannot be used in food industry as long as there is the concern that a bolt may fall out and get mixed into the food as foreign material. Therefore, there has been a demand for modification and improvement that dispel this concern. 
         [0008]    It is an object of the present invention to provide an internal joint having an excellent appearance design in a position connecting pipes. The pipe connection joint can be physically and surely increased in pipe-connecting strength to the necessary extent. Furthermore, in spite of using a bolt for pipe connection, there is no such concern that the bolt may come loose and fall out in a long in-service period, so that the joint is suitable for use even in food industry. At the same time, the pipes can be easily disconnected, which makes the joint excellent in recycling efficiency. 
         [0009]    In order to solve the above-mentioned concern, a first aspect of the invention provides a pipe joint including a joint body  11  in which one or more connecting inset portions  12  extending from the joint body  11  and each inserted in an internal bore  1   a  of a corresponding pipe to be connected  1  are each formed to have a hollow structure, a plurality of long slit-like splits  13  are formed in each of the connecting inset portions  12  in a circumferential direction to axially extend from an end of the corresponding connecting inset portion  12 , and the connecting inset portion  12  is further provided in a hollow interior thereof with a tapered portion  14  with an internal diameter decreasing from the end thereof toward the joint body  11 ; a tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12 ; and a stop bolt  3  having a conical portion  3   a  in an end portion thereof, wherein the tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12  has a rear part in which a tapered portion for diameter expansion  20  is formed, which has a diameter smaller than an external diameter of the connecting inset portion  12  and is brought into internal contact with the tapered portion  14  formed in the hollow interior of the connecting inset portion  12 , and the tapered sleeve  2  further has a front part in which a hole  21  to be inserted with the conical portion  3   a  of the stop bolt  3  is formed orthogonally to an axis of the tapered sleeve  2 ; wherein a screw hole  15  is formed in the joint body  11  orthogonally to an axis of the joint body  11 , screw hole  15  being located in a position reached by the hole  21  of the tapered sleeve  2  that has been inserted in the hollow interior of the connecting inset portion  12  up to a given position but so as to be slightly misaligned in a direction of inserting the tapered sleeve  2 ; and wherein the tapered sleeve  2  is inserted in the hollow interior of the connecting inset portion  12  up to the given position; the connecting inset portion  12  is inserted in the internal bore  1   a  of the pipe to be connected  1 ; and the stop bolt  3  is put into the screw hole  15  of the joint body  11  to make the conical portion  3   a  of the stop bolt  3  enter the hole  21  of the tapered sleeve  2 , with the result that the tapered sleeve  2  is pulled by an amount of the misalignment to increase the connecting inset portion  12  in diameter by wedge effect of the tapered portion for diameter expansion  20 , and the pipe  1  is then crimped and fixed from the inside to be connected. 
         [0010]    A second aspect of the invention provides the pipe joint  10  according to the first aspect, wherein the screw hole  15  formed in the joint body  11  is a non-through hole leading to the hole  21  of the tapered sleeve  2 ; the hole  21  of the tapered sleeve  2  is a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 ; and the stop bolt  3  has such length as to sink deep into an outer circumferential surface of the joint body  11  when the conical portion  3   a  is inserted into the tapered hole  21  of the tapered sleeve  2  to pull the tapered sleeve  2  by the amount of the misalignment. 
         [0011]    A third aspect of the invention provides a pipe joint including a joint body  11  in which one or more connecting inset portions  12  extending from the joint body  11  and each inserted in an internal bore of a corresponding pipe to be connected  1  are each formed to have a hollow structure, a plurality of long slit-like splits are formed in each of the connecting inset portions  12  in a circumferential direction to axially extend from an end of the corresponding connecting inset portion  12 , and the connecting inset portions  12  is further provided in a hollow interior thereof with a tapered portion  14  having an internal diameter that is gradually reduced from the end thereof toward the joint body; a tapered sleeve  2  to be inserted in the hollow interior of the corresponding connecting inset portion  12 ; and a stop bolt  3  having a conical portion  3   a  in an end portion thereof, wherein the tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12  has a rear part in which a tapered portion for diameter expansion  20  is formed, which has a diameter smaller than an external diameter of the connecting inset portion  12  and is brought into internal contact with the tapered portion  14  formed in the hollow interior of the connecting inset portion  12 , and the tapered sleeve  2  further has a front part in which a hole  21  to be inserted with the conical portion  3   a  of the stop bolt  3  is formed orthogonally to an axis of the tapered sleeve  2 ; wherein a screw hole  16  is formed in the connecting inset portion orthogonally to an axis of the connecting inset portion  12 , the screw hole  16  being located in a position reached by the hole  21  of the tapered sleeve  2  that has been inserted in the hollow interior of the connecting inset portion up to a given position but so as to be slightly misaligned in a direction of inserting the tapered sleeve  2 ; and wherein the tapered sleeve  2  is inserted in the hollow interior of the connecting inset portion  12  up to the given position; the stop bolt  3  is put into the screw hole  16  of the connecting inset portion  12  until sinking into an outer circumferential surface of the connecting inset portion; the connecting inset portion  12  is inserted into the internal bore of the pipe to be connected  1  so that a through hole  1   b  that has previously been formed in the pipe  1  is aligned with the screw hole  16  of the connecting inset portion  12 ; the stop bolt  3  inserted in the connecting inset portion  12  is tightened with a tool inserted from the through hole  1   b  of the pipe  1  to make the conical portion  3   a  enter the hole  21  of the tapered sleeve  2 , with the result that the tapered sleeve  2  is pulled by an amount of the misalignment to increase the connecting inset portion  12  in diameter by wedge effect of the tapered portion for diameter expansion  20 , and the pipe  1  is then crimped and fixed from the inside to be connected. 
         [0012]    A fourth aspect of the invention provides the pipe joint according to the third aspect, wherein the through hole  1   b  that has previously been formed in the pipe  1  has a minimum diameter to allow the tool to be inserted and turn the stop bolt  3  that has been put into the screw hole  16  of the connecting inset portion  12 ; wherein the stop bolt  3  has an entire length including the conical portion  3   a,  which is equal to or slightly more than an entire length of the screw hole  16  of the connecting inset portion  12 ; and wherein the hole  21  formed in the front part of the tapered sleeve  2  is a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 . 
         [0013]    A fifth aspect of the invention provides a pipe joint including a joint body  11  in which one or more connecting inset portions  12  extending from the joint body  11  and each inserted in an internal bore of a corresponding pipe to be connected  1  are each formed to have a hollow structure, a plurality of long slit-like splits are formed in each of the connecting inset portions  12  in a circumferential direction to axially extend from an end of the corresponding connecting inset portion  12 , and the connecting inset portion  12  is further provided in a hollow interior thereof with a tapered portion  14  having an internal diameter decreasing from the end thereof toward the joint body  11 ; a tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12 ; and a stop bolt  3  having a conical portion  3   a  in an end portion thereof, wherein the tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12  has a rear part in which a tapered portion for diameter expansion  20  is formed, which has a diameter smaller than an external diameter of the connecting inset portion  12  and is brought into internal contact with the tapered portion  14  formed in the hollow interior of the connecting inset portion  12 , and the tapered sleeve  2  further has a front part in which a screw hole  22  formed through the tapered sleeve  2  so as to extend orthogonally to an axis of the tapered sleeve  2 ; wherein a through hole  18  is formed in the joint body  11  orthogonally to an axis of the joint body  11 , the through hole  18  being located in a position reached by the screw hole  22  of the tapered sleeve  2  that has been inserted in the hollow interior of the connecting inset portion  12  up to a given position but so as to be slightly misaligned in a direction of inserting the tapered sleeve  2 , and wherein the stop bolt  3  is previously put into the screw hole  22  of the tapered sleeve  2  until sinking into an outer circumferential surface of the tapered sleeve  2 ; the tapered sleeve  2  is inserted into the hollow interior of the connecting inset portion  12  up to the given position; the connecting inset portion  12  is inserted into the internal bore of the pipe to be connected  1 ; and the stop bolt  3  of the tapered sleeve  2  is tightened with a tool inserted from the through hole  18  of the joint body  11  to make the conical portion  3   a  enter the hole  18   a  of the joint body  11 , with the result that the tapered sleeve  2  is pulled by an amount of the misalignment to increase the connecting inset portion  12  in diameter by wedge effect of the tapered portion for diameter expansions  20 , and the pipe  1  is then crimped and fixed from the inside to be connected. 
         [0014]    A sixth aspect of the invention provides the pipe joint according to the fifth aspect, wherein the through hole  18  of the joint body  11  is formed as a hole  18  extending from an open end thereof and leading to the screw hole of the tapered sleeve, and a hole  1   a  extending from the above hole has a bottom and is formed as a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 ; and wherein the stop bolt  3  has an entire length including the conical portion  3   a,  which is equal to or less than an entire length of the screw hole  22  of the tapered sleeve  2 . 
         [0015]    A seventh aspect of the invention provides a pipe joint including a joint body  11  in which one or more connecting inset portions  12  extending from the joint body  11  and each inserted in an internal bore of a corresponding pipe to be connected  1  are each formed to have a hollow structure, a plurality of long slit-like splits are formed in each of the connecting inset portions  12  in a circumferential direction to axially extend from an end of the corresponding connecting inset portion  12 , and the connecting inset portion  12  is further provided in a hollow interior thereof with a tapered portion  14  having an internal diameter decreasing from the end thereof toward the joint body  11 ; a tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12 ; and a stop bolt  3  having a conical portion  3   a  in an end portion thereof; wherein the tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12  has a rear part in which a tapered portion for diameter expansion  20  is formed, which has a diameter smaller than an external diameter of the connecting inset portion  12  and is brought into internal contact with the tapered portion  14  formed in the hollow interior of the connecting inset portion  12 , and the tapered sleeve  2  further has a front part in which a screw hole  22  is formed through the tapered sleeve  2  so as to extend orthogonally to an axis of the tapered sleeve  2 ; wherein a through hole  19  is formed in the connecting inset portion orthogonally to an axis of the connecting inset portion  12 , the through hole  19  being located in a position reached by the screw hole  22  of the tapered sleeve  2  that has been inserted in the hollow interior of the connecting inset portion  12  up to a given position but so as to be slightly misaligned in a direction of inserting the tapered sleeve  2 ; and wherein the stop bolt  3  is previously put in the screw hole  22  of the tapered sleeve  2  until sinking into an outer circumferential surface of the tapered sleeve  2 ; the tapered sleeve  2  is inserted in the hollow interior of the connecting inset portion  12  up to the given position; the connecting inset portion  12  is inserted in the internal bore of the pipe to be connected  1  so that a through hole  1   b  that has previously been formed in the pipe  1  is aligned with the through hole  19  of the connecting inset portion  12 ; and the stop bolt  3  inserted in the tapered sleeve  2  is tightened with a tool inserted from the through holes  1   b  and  19  to make the conical portion  3   a  enter a hole  19   a  of the connecting inset portion  12 , with the result that the tapered sleeve is pulled by an amount of the misalignment to increase the connecting inset portion  12  in diameter by wedge effect of the tapered portion for diameter expansion, and the pipe  1  is then crimped and fixed from the inside to be connected. 
         [0016]    An eighth aspect of the invention provides the pipe joint according to the seventh aspect, wherein the through hole  19  of the connecting inset portion  12  is formed as a hole extending from an open end thereof and leading to the screw hole  22  of the tapered sleeve  2 , and a hole  19   a  extending from the above hole has a bottom and is formed as a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 ; wherein the through hole  1   b  that has previously been formed in the pipe  1  has a minimum diameter to allow the tool to be inserted and turn the stop bolt  3  that has been put into the screw hole  22  of the tapered sleeve  2 ; and wherein the stop bolt  3  has an entire length including the conical portion  3   a,  which is equal to or less than an entire length of the screw hole  22  of the tapered sleeve  2 . 
         [0017]    A ninth aspect of the invention provides a pipe joint including a joint body  11  in which one or more connecting inset portions  12 ′ extending from the joint body  11  and each inserted in an internal bore of a corresponding pipe to be connected  1  are each formed to have a hollow structure, and an outer circumferential surface of the joint body  11  has a tapered shape; a pin sleeve  2 ′ to be inserted in the hollow interior of the corresponding connecting inset portion  12 ′, a split sleeve  40  including one axial split  41 , having an inner circumferential surface in a tapered shape identical to the tapered shape of an outer circumferential surface of the connecting inset portion  12 ′ and an outer circumferential surface that has a substantially uniform external diameter in internal contact with the internal bore of the pipe  1 ; and a stop bolt  3  having a conical portion  3   a  in an end portion thereof; wherein the pin sleeve  2 ′ to be inserted in the hollow interior of the connecting inset portion  12 ′ has a rear part in which a flange-shaped head  23  is formed, and further has a front part in which a hole  21  inserted with the conical portion  3   a  of the stop bolt is formed orthogonally to an axis of the pin sleeve, wherein a screw hole  15  is formed in the joint body  11  orthogonally to an axis of the joint body  11 , the screw hole  15  being located in a position reached by the hole  21  of the pin sleeve  2 ′ that has been inserted in the hollow interior of the connecting inset portion  12 ′ up to a given position but so as to be slightly misaligned in a direction of inserting the pin sleeve  2 ′; and wherein the split sleeve  40  is fitted to the outer circumferential surface of the connecting inset portion  12 ′ so that the tapered shape of the split sleeve  40  and that of the connecting inset portion  12 ′ coincide with each other; the pin sleeve  2 ′ is inserted into the hollow interior of the connecting inset portion up to the given position; the connecting inset portion  12 ′ is inserted in the internal bore of the pipe to be connected  1 ; the stop bolt  3  is put into the screw hole  15  of the joint body  11  to make the conical portion  3   a  of the stop bolt  3  enter the hole  21  of the pin sleeve  2 ′, with the result that the pin sleeve  2 ′ is pulled by an amount of the misalignment; the split sleeve  40  is further moved in the same direction to increase the split sleeve  40  in diameter by inclination of the tapered portion, and the pipe  1  is then crimped and fixed from the inside to be connected. 
         [0018]    A tenth aspect of the invention provides the pipe joint according to the ninth aspect, wherein the screw hole  15  of the joint body  11  is formed as a non-through hole leading to the hole of the pin sleeve  2 ′; wherein the hole  21  formed in the front part of the pin sleeve  2 ′ is a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 ; wherein the stop bolt  3  has such length as to sink deep into an outer circumferential surface of the joint body  11  when the conical portion  3   a  is inserted into the tapered hole  21  of the tapered sleeve  2  to pull the pin sleeve  2 ′ by the amount of the misalignment; and wherein the tapered shape of the inner circumferential surface of the split sleeve  40  is of such size that a rear end of the split sleeve  40  protrudes from an end of the connecting inset portion  12 ′ in a position where the split sleeve  40  is fitted onto the outer circumferential surface of the connecting inset portion  12 ′ so that the tapered shape of the split sleeve  40  and that of the connecting inset portion  12 ′ coincide with each other, and is of such length that the split sleeve  40  is out of contact with a base of the connecting inset portion  12 ′ when pulled by the pin sleeve by an amount of the misalignment. 
         [0019]    An eleventh aspect of the invention provides a pipe joint including a joint body  11  in which one or more connecting inset portions  12 ′ extending from the joint body  11  and each inserted in an internal bore of a corresponding pipe to be connected  1  are each formed to have a hollow structure, and an outer circumferential surface of the joint body  11  has a tapered shape; a pin sleeve  2 ′ to be inserted in the hollow interior of the connecting inset portion  12 ′; a split sleeve  40  with one axial split  41 , which has an inner circumferential portion in a tapered shape identical to the tapered shape of the outer circumferential surface of the connecting inset portion  12 ′ and an outer circumferential surface with a substantially uniform external diameter that is in internal contact with the internal bore of the pipe  1 ; and a stop bolt  3  having a conical portion  3   a  in an end portion thereof; wherein the pin sleeve  2 ′ to be inserted in the hollow interior of the connecting inset portion  12 ′ has a rear end in which a flange-shaped head is formed and a front part in which a hole  21  inserted with the conical portion  3   a  of the stop bolt  3  is formed orthogonally to an axis of the pin sleeve  2 ′; wherein a screw hole  16  is formed in the connecting inset portions  12 ′ orthogonally to an axis of the corresponding connecting inset portion  12 ′, the screw hole  16  being located in a position reached by the hole  21  of the pin sleeve  2 ′ that has been inserted in the hollow interior of the connecting inset portion  12 ′ up to a given position but so as to be slightly misaligned in a direction of inserting the pin sleeve  2 ′; and wherein the split sleeve  40  is fitted to the outer circumferential surface of the connecting inset portion  12 ′ so that the tapered shape of the split sleeve  40  and that of the connecting inset portion  12 ′ coincide with each other; the pin sleeve  2 ′ is inserted into the hollow interior of the connecting inset portion up to the given position; the stop bolt  3  is put into the screw hole  16  of the connecting inset portion  12 ′ until a rear end of the stop bolt  3  sinks to a position where the pipe  1  can be inserted; the connecting inset portion  12 ′ is then inserted into the internal bore of the pipe to be connected  1  so that a through hole  1   b  that has previously been formed in the pipe  1  is aligned with the screw hole  16  of the connecting inset portion  12 ′; the stop bolt  3  inserted in the connecting inset portion  12 ′ is tightened with a tool inserted from the through hole  1   b  of the pipe  1  to make the conical portion  3   a  enter the hole  21  of the pin sleeve  2 ′, with the result that the pin sleeve  2 ′ is pulled by an amount of the misalignment; the split sleeve  40  is further moved in the same direction to increase the split sleeve  40  in diameter by inclination of the tapered portion, and the pipe  1  is then crimped and fixed from the inside to be connected. 
         [0020]    A twelfth aspect of the invention provides the pipe joint according to the eleventh aspect, wherein the through hole  1   b  that has previously formed in the pipe  1  has a minimum diameter to allow the tool to be inserted and turn the stop bolt  3  that has been put into the screw hole  16  of the connecting inset portion  12 ′; wherein the stop bolt  3  has an entire length including the conical portion  3   a,  which is equal to or slightly more than an entire length of the screw hole  16  of the connecting inset portion  12 ′; wherein the hole  21  formed in the front part of the pin sleeve  2 ′ is a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 ; and wherein the screw hole  16  of the connecting inset portion  12 ′ is located close to a base of the connecting inset portion  12 ′. 
         [0021]    A thirteenth aspect of the invention provides the pipe joint according to any one of the aspects 1 to 12, wherein the joint body  11  has an outline of the same shape and size as the pipe  1 . 
         [0022]    Since the joint according to the invention is an internal type that inserts the connecting inset portion  12  extending from the joint body  11  into the internal bore of the pipe to be connected  1 , the joint body  11  is inconspicuous. Therefore, the joint is excellent in appearance design when connecting the pipe  1 . 
         [0023]    The stop bolt  3  for pulling the tapered sleeve  2  or  2 ′ is used as means for surely increasing the strength of connecting the pipe  1  to the necessary extent. In the invention according to the third and fourth aspects or the fifth and sixth aspects, and the eleventh and twelfth aspects, the hole  1   b  with a diameter smaller than the external diameter of the stop bolt  3  certainly prevents the stop bolt  3  from falling out. This completely dispels the concern that the stop bolt  3  may come off and fall out in a long in-service period. Consequently, the joint according to the invention can be suitably used even in food industry that is intolerant of the possibility that foreign material may get mixed into the food. 
         [0024]    In addition, according to the joint of the invention, the pipe  1  can be disconnected without difficulty by loosening the stop bolt  3  with a screw-turning tool such as a wrench  4 . This makes the joint excellent in recycling efficiency. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1  is an exploded perspective view showing a joint of the invention according to Embodiment 1; 
           [0026]      FIG. 2  is a plan view showing pipe connection using the joint; 
           [0027]      FIG. 3  is a sectional view, taken along line A-A of  FIG. 2 ; 
           [0028]      FIG. 4  is a perspective view of a variation in which a joint body is modified in shape; 
           [0029]      FIG. 5A  is a perspective view of a variation in which a joint body is modified in shape; 
           [0030]      FIG. 5B  is a perspective view of a variation in which a joint body is modified in shape; 
           [0031]      FIG. 6A  is a perspective view of a variation in which a joint body is modified in shape; 
           [0032]      FIG. 6B  is a perspective view of a variation in which a joint body is modified in shape; 
           [0033]      FIG. 7  is a sectional view of a joint of the invention according to Embodiment 2 in a use state; 
           [0034]      FIG. 8  is a sectional view of a joint of the invention according to Embodiment 3 in a use state; 
           [0035]      FIG. 9  is a sectional view of a joint of the invention according to Embodiment 4 in a use state; 
           [0036]      FIG. 10  is an exploded perspective view of a joint of the invention according to Embodiment 5; 
           [0037]      FIG. 11  is a sectional view showing pipe connection using the joint; 
           [0038]      FIG. 12  is an exploded perspective view of a joint of the invention according to Embodiment 6; and 
           [0039]      FIG. 13  is a sectional view of pipe connection using the joint. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0040]    A joint  10  includes a joint body  11  in which one or more connecting inset portions  12  extending from the joint body  11  and each inserted in an internal bore  1   a  of a corresponding pipe to be connected  1  are each formed to have a hollow structure, a plurality of long slit-like splits  13  are circumferentially formed in each of the connecting inset portions  12  to axially extend from an end of the corresponding connecting inset portion  12 , and the connecting inset portions  12  is provided in a hollow interior thereof with a tapered portion  14  having an internal diameter decreasing from the end thereof toward the joint body  11 ; a tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12 ; and a stop bolt  3  having a conical portion  3   a  in an end portion thereof. 
         [0041]    In a rear part of the tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12 , there is formed a tapered portion for diameter expansion  20  having a diameter smaller than an external diameter of the connecting inset portion  12  and brought into internal contact with the tapered portion  14  formed in the hollow interior of the connecting inset portion  12 . Also in a front part of the tapered sleeve  2 , a hole  21  to be inserted with the conical portion  3   a  of the stop bolt  3  is formed orthogonally to an axis of the tapered sleeve  2 . 
         [0042]    A screw hole  15  is formed in the joint body  11  orthogonally to an axis of the joint body  11 . The screw hole  15  is located in a position reached by the hole  21  of the tapered sleeve  2  that has been inserted in the hollow interior of the connecting inset portion  12  up to a given position but so as to be slightly misaligned in a direction of inserting the tapered sleeve  2 . 
         [0043]    First, the tapered sleeve  2  is inserted in the hollow interior of the connecting inset portion  12  up to the given position, and the connecting inset portion  12  is subsequently inserted in the internal bore  1   a  of the pipe to be connected  1 . Secondly, the stop bolt  3  is put into the screw hole  15  of the joint body  11  so that the conical portion  3   a  of the stop bolt  3  enters the hole  21  of the tapered sleeve  2 , to thereby pull the tapered sleeve  2  by an amount of the misalignment. As a result, the connecting inset portion  12  is increased in diameter by wedge effect of the tapered portion for diameter expansion  20 . The pipe  1  is consequently crimped and fixed from the inside to be connected to the joint body  11 . Since the tapered sleeve  2  is pulled into the connecting inset portion  12 , the stop bolt  3  is applied with force acting orthogonally to a bolt-escaping direction and a frictional force. This creates large resistance that prevents the stop bolt  3  from coming loose and falling out. 
       Embodiment 1 
       [0044]    The invention will be described below according to embodiments illustrated in the drawings. 
         [0045]      FIGS. 1 to 3  show an embodiment of the invention according to the first and second aspects. In a pipe joint  10  of the embodiment, three connecting inset portions  12 , according to the embodiment shown in  FIG. 1 , which extend from a joint body  11  and are inserted in internal bores  1   a  of respective pipes to be connected  1 , are each formed to have a hollow structure. A plurality of long slit-like splits  13  are formed in each of the connecting inset portions  12  at substantially regular intervals as viewed in a circumferential direction so as to axially extend from an end of the corresponding connecting inset portion  12  almost over an entire length of the connecting inset portion  12 . This provides the connecting inset portion  12  with radial flexibility. The flexibility of the connecting inset portion  12  makes it easy to fit the connecting inset portion  12  into an internal bore  1   a  of a corresponding pipe  1 , and is also convenient for facilitating diameter expansion by wedge effect of a tapered portion for diameter expansion which is formed in a tapered sleeve  2  mentioned below. As is apparent from  FIG. 3 , for example, the connecting inset portion  12  is provided in a hollow interior thereof with a tapered portion  14  having an internal diameter decreasing from the end thereof toward the joint body  11 . The joint  10  has the tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion and a stop bolt  3  including a conical portion  3   a  in an end portion thereof. 
         [0046]    In a rear part of the tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12 , there is formed a tapered portion for diameter expansion  20  which has a diameter smaller than an external diameter of the connecting inset portion  12  and is brought into substantially tight internal contact with the tapered portion  14  formed in the hollow interior of the connecting inset portion  12  as illustrated in  FIG. 3 . In a front part of the tapered sleeve  2 , there is formed a hole  21  in which the conical portion  3   a  of the stop bolt  3  is inserted orthogonally to an axis of the tapered sleeve  2  as illustrated in  FIG. 3 . 
         [0047]    The joint body  11  includes a screw hole  15  that extends orthogonally to an axis of the joint body  11 . The screw hole  15  is located in a position reached by the hole  21  of the tapered sleeve  2  that has been inserted in the hollow interior of the connecting inset portion  12  up to a given position (predetermined position) but so as to be slightly misaligned in a direction of inserting the tapered sleeve  2  (see the left-side part of  FIG. 3 ). 
         [0048]    A method of connecting the pipe  1  using the joint  10  thus constructed will be described below. 
         [0049]    First, the tapered sleeve  2  is inserted into the hollow interior of the corresponding connecting inset portion  12  up to the given position (predetermined position). After a center alignment is carried out between the hole  21  formed in the front part of the tapered sleeve  2  and the screw hole  15  of the joint body  11 , the connecting inset portion  12  is inserted into the internal bore  1   a  of the corresponding pipe to be connected  1 . Secondly, the stop bolt  3  having the conical portion  3   a  in the end portion thereof is firmly tightened into the screw hole  15  of the joint body  11  with a screw-turning tool such as a wrench  4  shown in  FIG. 1  so that the conical portion  3   a  enters the hole  21  of the tapered sleeve  2 . As a result, the tapered sleeve  2  is pulled by an amount of the misalignment between the screw hole  15  and the hole  21 . In proportion to the pulling amount, the tapered portion for diameter expansion  20  moves into the tapered portion  14  of the connecting inset portion  12 , thereby exerting the wedge effect that bends the connecting inset portion  12  in a radial outward direction. In other words, an end portion of the connecting inset portion  12  is increased in diameter as a whole, so that a bore surface of the pipe  1  is crimped hard from the inside and fixed by frictional force. Consequently, the pipe  1  can be firmly connected to the joint body  11 .  FIG. 2  shows a state in which three pipes  1  are connected to the joint body  11  in the above-described manner. 
         [0050]    According to Embodiment 1, the screw hole  15  formed in the joint body  11  is a hole that is open only at an upper end and reaches the hollow interior so as to lead to the hole  21  of the tapered sleeve  2  as illustrated in  FIG. 3 . In order to connect the three pipes  1 , the joint body  11  is provided with three screw holes  15  located close to the respective connecting inset portion  12 , and open ends of the screw holes  15  are seen. This provides the advantage that an external design is good as a joint, and that there are not many concave portions that are prone to gather dust. 
         [0051]    The joint body  11  has an outline of the same shape and size as the pipe  1 . That is to say, the joint body  11  has such a structure that no step, which is caused by different diameters, is produced between the joint body  11  and the pipe  1 . In this respect, too, the external design of a pipe-connecting structure is good. In addition, because of the connecting structure that scarcely gathers dust, the joint  10  is suitable to be used in food industry that is intolerant of dust. 
         [0052]    Embodiment 1 illustrated in the drawings has such a design that both the pipe  1  and the joint body  11  have a generally circular outline. In stead of the circular shape, however, it is possible to carry out Embodiment 1 with a square or polygonal outline. These matters will also apply to other embodiments described below. 
         [0053]    The hole  21  of the tapered sleeve  2  in Embodiment 1 is a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3  (that is, substantially the same shape and size) as is evident especially from the left-side part of  FIG. 3 . For this reason, in spite that the screw hole  15  and the tapered hole  21  are slightly misaligned with each other, the conical portion  3   a  of the stop bolt  3  smoothly enters the tapered hole  21 . Both the conical portion  3   a  and the tapered hole  21  are brought into almost line or surface contact with each other, and pulls the tapered sleeve  2  into the hollow interior of the connecting inset portion  12  by the amount of the misalignment without difficulty. In this way, the screw hole  15  and the tapered hole  21  contribute a firm connection between the pipe  1  and the joint body  11 . 
         [0054]    The stop bolt  3  has such length that the rear end (upper end) thereof becomes a flush surface with or sinks a little deep into the outer circumferential surface of the joint body  11  as illustrated in the right-side part of  FIG. 3  when the tapered potion  3   a  enters the hole  21  of the tapered sleeve  2  to the necessary extent. Accordingly, the connecting structure of the pipe  1  and the joint body  11  is not obtrusive in appearance, and has not any protrusions having unpleasant touch. In this respect, Embodiment 1 has an excellent design and is comfortable in use. 
         [0055]      FIGS. 4 ,  5  and  6  show design forms of the joint body  11 , and more specifically, a basic form of the joint body  11  and main variations of the design form, in which the number of connecting inset portions  12  extending to be connected to pipes  1  and the extending directions of the connecting inset portions  12  are varied. 
         [0056]    First, a joint body  11 A illustrated in  FIG. 4  has a shape of a straight tube. Two connecting inset portions  12  extend from respective ends of the joint body  11 A. 
         [0057]    The joint body  11 B illustrated in  FIG. 5A  is of a so-called elbow type that is bent substantially at a right angle. Two connecting inset portions  12  extend from respective ends of the joint body  11 B. 
         [0058]    A joint body  11 C illustrated in  FIG. 5B  is of a three-axis type having an elbowed portion that is bent substantially at a right angle in a horizontal direction and a portion stretching in a perpendicularly downward (or upward) direction. Three connecting inset portions  12  extend from respective ends of the joint body  11 C. 
         [0059]    A joint body  11 D illustrated in  FIG. 6A  is of a three-axis type having a so-called T-shaped portion stretching in a horizontal direction and a portion stretching in a perpendicularly downward (or upward) direction. Four connecting inset portions  12  extend from respective ends of the joint body  11 D. 
         [0060]    A joint body  11 E illustrated in  FIG. 6B  is of a three-axis type having portions stretching in a horizontal direction to cross each other at right angles and a portion stretching in a perpendicularly downward (or upward) direction. Five connecting inset portions  12  extend from respective ends of the joint body  11 E. 
         [0061]    The above-described variations of the design form are merely specific examples of the basic form of the joint body  11  and the forms in which the number of connecting inset portions  12  and the direction in which the connecting inset portions  12  extend from the joint body  11  are different, and are not limited to the foregoing. 
         [0062]    The same design variations will also apply to other embodiments described below. 
       Embodiment 2 
       [0063]      FIG. 7  shows an embodiment of the invention according to the third and fourth aspects. 
         [0064]    A joint of Embodiment 2 ( FIG. 7 ) has a basic structure identical in many points to Embodiment 1. To be concrete, a connecting inset portion  12  extending from a joint body  11  and inserted in an internal bore of a pipe to be connected  1  is formed to have a hollow structure. The connecting inset portion  12  has a plurality of long slit-like splits circumferentially arranged at substantially regular intervals so as to axially extend from an end of the connecting inset portion  12 . In a hollow interior of the connecting inset portion  12 , there is formed a tapered portion  14  having an internal diameter decreasing from the end thereof toward the joint body  11 . The joint includes a tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12  of the joint body  11  and a stop bolt  3  having a conical portion  3   a  in an end portion thereof. 
         [0065]    In Embodiment 2, as in Embodiment 1, the tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12  of the joint body  11  is provided in a rear part with a tapered portion for diameter expansion  20  which has a diameter smaller than an external diameter of the connecting inset portion  12  and is brought into internal contact with the tapered portion  14  formed in the hollow interior of the connecting inset portion  12 . In a front part (shaft portion) of the tapered sleeve  2 , a hole  21  to be inserted with a conical portion  3   a  of a stop bolt  3  is formed orthogonally to an axis of the tapered sleeve  2 . The hole  21  shown in  FIG. 7  is formed as a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 . 
         [0066]    According to Embodiment 2, a screw hole  16  is formed in the connecting inset portion  12  orthogonally to an axis of the connecting inset portion  12  to run through to the hollow interior. The screw hole is located in a position reached by the hole  21  of the tapered sleeve  2  that has been inserted in the hollow interior of the connecting inset portion  12  up to a given position (predetermined position) but so as to be slightly misaligned in a direction of inserting the tapered sleeve  2 . Therefore, in Embodiment 2, when the connecting inset portion  12  is interfitted in the pipe  1 , the screw hole  16  is hidden by the pipe  1 , and so is the stop bolt  3  that has been put into the screw hole  16 . 
         [0067]    In order to tighten the stop bolt  3  in the screw hole  16 , the pipe  1  is previously provided in a required place with a through hole  1   b  that allows a screw-turning tool, such as the wrench  4  shown in  FIG. 1  as an example, to pass therethrough. 
         [0068]    A method for connecting the pipe  1  using the joint thus constructed will be described below. 
         [0069]    To connect the pipe  1  by using the joint of Embodiment 2, the tapered sleeve  2  is first inserted into the hollow interior of the connecting inset portion  12  up to the given position (predetermined position), and center alignment is carried out between the hole  21  formed in the front part of the tapered sleeve  2  and the screw hole  16  of the connecting inset portion  12 . The stop bolt  3  having the conical portion  3   a  in the end portion thereof is put into the screw hole  16  of the connecting inset portion  12  so that at least a rear end of the stop bolt  3  sinks into an outer circumferential surface of the connecting inset portion  12 . The connecting inset portion  12  is subsequently inserted into the internal bore of the pipe  1 , and the through hole  1   b  that has previously been formed in the pipe  1  is aligned with the screw hole  16  (see the left-side part of the  FIG. 7 ). Thereafter, the wrench  4  is inserted through the through hole  1   b,  and the stop bolt  3  in the screw hole  16  of the connecting inset portion  12  is tightened to make the conical portion  3   a  enter the tapered hole  21  of the tapered sleeve  2 . By so doing, the tapered sleeve  2  is pulled by the stop bolt  3  by an amount of the misalignment. The connecting inset portion  12  is increased in diameter due to a wedge effect of the tapered portion for diameter expansion  20 , and is then crimped and fixed to the pipe  1  from the inside. A firm connection between the pipe  1  and the joint body  11  can be thus achieved as in Embodiment 1. 
         [0070]    In Embodiment 2, the through hole  1   b  that has previously been formed in the pipe  1  preferably has a minimum diameter to allow the screw-turning tool such as the wrench  4  to be inserted and turn the stop bolt  3  that has been put into the screw hole  16  of the connecting inset portion  12  as illustrated in  FIG. 7  (the through hole  1   b  has a diameter of about 3 mm, for example, when the stop bolt  3  has an external diameter of about 6 mm). This makes the through hole  1   b  unnoticeable and therefore provides a good design in terms of appearance of the pipe  1 . Furthermore, the through hole  1   b  is not likely to gather dust. More importantly, since the diameter of the through hole  1   b  is smaller than the external diameter of the stop bolt  3 , even if the stop bolt  3  comes loose and is backed off, the rear end of the bolt  3  hits against a bore surface of the pipe  1 . As a result, and the bolt  3  is mechanically prevented from being further backed off, and there is no such concern that the bolt  3  may fall out. 
         [0071]    For a practical reason, the stop bolt  3  of Embodiment 2 has an entire length including the conical portion  3   a,  which is slightly more than an entire length of the screw hole  16  of the connecting inset portion  12  (see the left-side part of  FIG. 7 ). 
         [0072]    The hole  21  formed in the front part of the tapered sleeve  2  is a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 . The point of doing so is as described under Embodiment 1. 
       Embodiment 3 
       [0073]      FIG. 8  shows an embodiment of the invention according to the fifth and sixth aspects. 
         [0074]    A joint of Embodiment 3 has a basic structure identical in many points to Embodiments 1 and 2. More specifically, a connecting inset portion  12  extending from a joint body  11  and inserted in an internal bore of a pipe to be connected  1  is formed to have a hollow structure. The connecting inset portion  12  also has a plurality of long slit-like splits that are circumferentially arranged to axially extend from an end of the connecting inset portion  12 . The connecting inset portion  12  is provided in a hollow interior thereof with a tapered portion  14  having an internal diameter decreasing from the end thereof toward the joint body. The joint includes a tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12  of the joint body  11  and a stop bolt  3  having a conical portion  3   a  in an end portion thereof. 
         [0075]    In a rear part of the tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12 , there is formed a tapered portion for diameter expansion  20  which has a diameter smaller than an external diameter of the connecting inset portion  12  and is brought into internal contact with the tapered portion  14  formed in the hollow interior of the connecting inset portion  12 . In a front part of the tapered sleeve  2 , a screw hole  22  is formed through the tapered sleeve  2  orthogonally to an axis of the tapered sleeve  2 . 
         [0076]    The joint body  11  includes a through hole  18  formed orthogonally to an axis of the joint body  11 . The through hole  18  is located in a position reached by the screw hole  22  of the tapered sleeve  2  that has been inserted in the hollow interior of the connecting inset portion  12  up to a given position but so as to be slightly misaligned in a direction of inserting the tapered sleeve  2 . 
         [0077]    To connect the pipe  1  by using the joint of Embodiment 3, first of all, a stop bolt  3  is previously put into the screw hole  22  of the tapered sleeve  2  and is brought into a position sinking into the outer circumferential surface of the tapered sleeve  2 . The tapered sleeve  2  in the above-mentioned state is inserted into the hollow interior of the connecting inset portion  12  up to the given position, and the hole  18  of the joint body  11  is aligned with the screw hole  22 . The connecting inset portion  12  is inserted into the internal bore of the pipe  1 . A screw-turning tool such as the wrench  4  shown in  FIG. 1  is inserted through the through hole  18  of the joint body  11  to tighten the stop bolt  3  inserted in the tapered sleeve  2 , to thereby make the conical portion  3   a  of the stop bolt  3  enter a hole  18   a  of the joint body  11 . As a result, the tapered sleeve  2  is pulled by an amount of the misalignment. The connecting inset portion  12  is then increased in diameter due to a wedge effect of the tapered portion for diameter expansion  20 . Consequently, the connecting inset portion  12  is crimped and fixed to the inside of the pipe  1 , which makes it possible to firmly connect the pipe  1 . 
         [0078]    In the joint according to Embodiment 3, as clearly seen in the left-side part of  FIG. 8 , the through hole  18  of the joint body  11  leads from an upper open end thereof to the screw hole  22  of the tapered sleeve  2 , whereas the lower hole  18   a  located on an extended line of the hole  18  has a bottom. The hole  18   a  is also formed as a tapered hole that follows the shape of the tapered potion  3   a  of the stop bolt  3 . Accordingly, the through hole  18  formed in the joint body  11  needs only one open end. This improves an external design of the joint body  11  and provides an operation of pulling the tapered sleeve  2  by the amount of the misalignment. Moreover, there is an advantage of reducing places liable to gather dust. 
         [0079]    The stop bolt  3  according to Embodiment 3 is formed under such a use condition that an entire length including the conical portion  3   a  is set equal to or less than an entire length of the screw hole  22  of the tapered sleeve  2  as clearly illustrated in the left-side part of  FIG. 8 . 
       Embodiment 4 
       [0080]      FIG. 9  shows an embodiment of the invention according to the seventh and eighth aspects. 
         [0081]    A joint of Embodiment 4 is, so to speak, a combination of Embodiments 2 and 3, so that it has a structure common in many points with Embodiments 2 and 3. To be more specific, a connecting inset portion  12  extending from a joint body  11  and inserted in an internal bore of a pipe to be connected  1  is formed to have a hollow structure. The connecting inset portion  12  has a plurality of long slit-like splits circumferentially arranged to axially extend from an end of the connecting inset portion  12 . In a hollow interior of the connecting inset portion  12 , there is formed a tapered portion  14  having an internal diameter decreasing from the end thereof toward the joint body  11 . The joint includes a tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12  of the joint body  11  and a stop bolt  3  having a conical portion  3   a  in an end portion thereof. 
         [0082]    In a rear part of the tapered sleeve  2  to be inserted in the hollow interior of the connecting inset portion  12 , there is formed a tapered portion for diameter expansion  20  which has a diameter smaller than an external diameter of the connecting inset portion  12  and is brought into internal contact with the tapered portion  14  formed in the hollow interior of the connecting inset portion  12 . In a front part of the tapered sleeve  2 , a screw hole  22  is formed through the tapered sleeve  2  orthogonally to an axis of the tapered sleeve  2 . 
         [0083]    The connecting inset portion  12  is provided with a through hole  19  that extends orthogonally to an axis of the connecting inset portion  12 . The through hole  19  is located in a position reached by the screw hole  22  of the tapered sleeve  2  that has been inserted in the hollow interior of the connecting inset portion  12  up to a given position but so as to be slightly misaligned in a direction of inserting the tapered sleeve  2 . 
         [0084]    To connect the joint thus constructed and the pipe  1  to each other, first of all, the stop bolt  3  is previously put into the screw hole  22  of the tapered sleeve  2 . As illustrated in the left-side part of  FIG. 9 , after the stop bolt  3  is caused to sink completely into an outer circumferential surface of the tapered sleeve  2 , the tapered sleeve  2  is inserted into the hollow interior of the connecting inset portion  12  up to the given position. The screw hole  22  is aligned with the through hole  19  of the connecting inset portion  12 . The connecting inset portion  12  is subsequently inserted into the internal bore of the pipe  1  so that a through hole  1   b  that has previously been formed in the pipe  1  is aligned with the hole  19  of the connecting inset portion  12 . A screw-turning tool such as the wrench  4  is inserted from the through hole  1   b  of the pipe  1  through the hole  19  of the connecting inset portion  12 , and the stop bolt  3  inserted in the tapered sleeve  2  is tightened and installed with the wrench  4 , to thereby insert the conical portion  3   a  into a hole  19   a  of the connecting inset portion  12 . By so doing, the tapered sleeve  2  is pulled by an amount of the misalignment. The connecting inset portion  12  is increased in diameter due to a wedge effect of the tapered portion for diameter expansion  20 , and is then crimped and fixed to the pipe  1 . Consequently, the pipe  1  can be firmly connected. 
         [0085]    In the joint according to Embodiment 4, as clearly illustrated in the left-side part of  FIG. 9 , the through hole  19  of the connecting inset portion  12  is formed as a through hole communicating with the screw hole  22  of the tapered sleeve  2  in a portion between an upper open end thereof and the hollow interior. The lower hole  19   a  formed on an extended line of the hole  19  is a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 . This is suitable for pulling the tapered sleeve  2  by the amount of the misalignment. 
         [0086]    According to Embodiment 4, the through holes  19  and  19   a  formed in the connecting inset portion  12  are covered with the pipe  1  at the time point when inserted into the pipe  1  and cannot be viewed from outside. The through hole  1   b  that has previously been formed in the pipe  1  has a minimum diameter to allow a screw-turning tool to be inserted and turn the stop bolt  3  that has been put into the screw hole  22  of the tapered sleeve  2 . For this reason, the through hole  1   b  that is viewed in the appearance of a pipe-connecting structure is inconspicuous, which provides a good design and reduces places liable to gather dust. If the stop bolt  3  comes loose and is backed off, the pipe  1  mechanically and entirely prevents the stop bolt  3  from falling out. 
         [0087]    As clearly illustrated in the left-side part of  FIG. 9 , the stop bolt  3  of Embodiment 4 has an entire length including the conical portion  3   a  which is equal to or less than an entire length of the screw hole  22  of the tapered sleeve  2 . 
       Embodiment 5 
       [0088]      FIGS. 10 and 11  show an embodiment of the invention according to the ninth and tenth aspects. 
         [0089]    In a joint of Embodiment 5, as symbolically illustrated in  FIG. 10 , two connecting inset portions  12 ′ extending from a joint body  11  and inserted in internal bores of respective pipes to be connected  1  are each formed to have a hollow structure. Each of the connecting inset portions  12 ′ has an outer circumferential surface in a tapered shape. The joint includes a pin sleeve  2 ′ to be inserted in a hollow interior of the connecting inset portion  12 ′ of the joint body  11 , a split sleeve  40  with one axial split  41 , which has an inner circumferential surface in a tapered shape identical to the tapered shape of the outer circumferential surface of the connecting inset portion  12 ′ and an outer circumferential surface with a substantially uniform external diameter that is in internal contact with the internal bore of the pipe  1  (see  FIG. 11 ), and a stop bolt  3  having a conical portion  3   a  in an end portion thereof. 
         [0090]    The pin sleeve  2 ′ to be inserted in the hollow interior of the connecting inset portion  12 ′ has a rear part provided with a simple flange-shaped head  23 . In a front part of the pin sleeve  2 ′, there is formed a hole  21  into which the conical portion  3   a  of the stop bolt  3  is inserted orthogonally to an axis of the pin sleeve. 
         [0091]    A screw hole  15  is formed in the joint body  11  orthogonally to an axis of the joint body  11 . The screw hole  15  is located in a position reached by the hole  21  of the pin sleeve  2 ′ that has been inserted in the hollow interior of the connecting inset portion  12 ′ up to a given position but so as to be slightly misaligned in a direction of inserting the pin sleeve  2 ′. 
         [0092]    To connect the joint of Embodiment 5 and the pipe  1  to each other, first of all, the split sleeve  40  is fitted to the outer circumferential surface of the connecting inset portion  12 ′ up to the position where the tapered shape of the split sleeve  40  coincides with that of the connecting inset portion  12 ′. Secondly, the pin sleeve  2 ′ is inserted into the hollow interior up to the given position so that the hole  21  formed in the front part of the pin sleeve  2 ′ is aligned with the screw hole  15  of the joint body  11 . The connecting inset portion  12 ′ is subsequently inserted into the internal bore of the pipe  1 . The stop bolt  3  is put into the screw hole  15  of the joint body  11  so as to make the conical portion  3   a  of the stop bolt  3  enter the hole  21  of the pin sleeve  2 ′. The pin sleeve  2 ′ is then pulled by an amount of the misalignment, which makes the split sleeve  40  move in the same direction. As a result, the split sleeve  40  is increased in diameter due to inclination of the tapered portion. Consequently, the pipe  1  is crimped and fixed from the inside, thereby being firmly connected. 
         [0093]    In the joint of Embodiment 5, as illustrated in  FIG. 11 , the screw hole  15  formed in the joint body  11  is a non-through hole leading to the hole  21  of the pin sleeve  2 ′ (half-through hole reaching the hollow interior). Therefore, the screw hole  15  has one open end. 
         [0094]    The hole  21  formed in the front part of the pin sleeve  2 ′ is a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 . This makes it possible to smoothly and reliably pull the pin sleeve  2 ′ by the amount of the misalignment. 
         [0095]    The stop bolt  3  has such length as to sink deep into the outer circumferential surface of the joint body  11  when the conical portion  3   a  is inserted into the tapered hole  21  of the pin sleeve  2 ′, and the pin sleeve  2 ′ is pulled by the amount of the misalignment. Therefore, the stop bolt  3  is not protruding from the outer circumferential surface of the joint body  11 , which provides a good external design. 
         [0096]    As illustrated in the left-side part of  FIG. 11 , the tapered shape of the inner circumferential surface of the split sleeve  40  is of such size that a rear end of the split sleeve  40  projects from the end of the connecting inset portion  12 ′ only by length m that is a several mm in the position where the split sleeve  40  is fitted to the outer circumferential surface of the connecting inset portion  12 ′ so as to fit the tapered shapes of the both. The tapered shape of the inner circumferential surface of the split sleeve  40  also has such length that, even if the split sleeve  40  is pulled by the pin sleeve  2 ′ by the amount of the misalignment, the split sleeve  40  is out of contact with a base of the connecting inset portion  12 ′, that is, a boundary step between the split sleeve  40  and the joint body  11 . It is then possible to easily and reliably carry out the pulling operation using the pin sleeve  2 ′ by the amount of the misalignment. 
       Embodiment 6 
       [0097]      FIGS. 12 and 13  show an embodiment of the invention according to the eleventh and twelfth aspects. 
         [0098]    A joint of Embodiment 6 differs from that of Embodiment 5 although a screw hole  16  for being inserted with a stop bolt  3  is formed in a connecting inset portion  12 ′ of a joint body  11 . 
         [0099]    The connecting inset portion  12 ′ extending from the joint body  11  and inserted in an internal bore of a pipe to be connected  1  is also formed to have a hollow structure. The connecting inset portion  12 ′ has an outer circumferential surface in a tapered shape. The joint includes a pin sleeve  2 ′ to be inserted in a hollow interior of the connecting inset portion  12 ′ of the joint body  11 , a split sleeve  40  with one axial split  41 , which has an inner circumferential surface in a tapered shape identical to the tapered shape of an outer circumferential surface of the connecting inset portion  12 ′ and an outer circumferential surface with a substantially uniform external diameter that is in internal contact with the internal bore of the pipe  1 , and a stop bolt  3  having a conical portion  3   a  in an end portion thereof. 
         [0100]    A flange-shaped head  23  is formed in a rear end of the pin sleeve  2 ′ to be inserted in the hollow interior of the connecting inset portion  12 ′. The pin sleeve  2 ′ is also provided in a front part thereof with a hole  21  for being inserted with the conical portion  3   a  of the stop bolt  3  orthogonally to an axis of the pin sleeve  2 ′. 
         [0101]    A screw hole  16  is formed in the connecting inset portion  12 ′ orthogonally to an axis of the connecting inset portion  12 ′. The screw hole  16  is located in a position reached by the hole  21  of the pin sleeve  2 ′ that has been inserted in the hollow interior of the connecting inset portion  12 ′ up to a given position but so as to be slightly misaligned in a direction of inserting the pin sleeve  2 ′. 
         [0102]    To connect the joint of Embodiment 6 and the pipe  1  to each other, first of all, the split sleeve  40  is fitted to the outer circumferential surface of the connecting inset portion  12 ′ up to a position where the tapered shapes of the both coincide with each other. The pin sleeve  2 ′ is inserted into the hollow interior of the connecting inset portion  12 ′ up to the given position. Center alignment of the hole  21  of the pin sleeve  2 ′ and the screw hole  16  of the connecting inset portion  12 ′ is carried out. The stop bolt  3  is put into the screw hole  16  of the connecting inset portion  12 ′ until a rear end (external end) of the stop bolt  3  is screwed down to a position where the pipe  1  is insertable. In this state, the connecting inset portion  12 ′ is inserted into the internal bore of the pipe  1 , and a through hole  1   b  that has previously been formed in the pipe  1  is aligned with the screw hole  16  of the connecting inset portion  12 ′. In the next place, the stop bolt  3  inserted in the connecting inset portion  12 ′ is tightened by a screw-turning tool such as the wrench  4  which is inserted from the through hole  1   b  of the pipe  1 . In this manner, the conical portion  3   a  is inserted into the hole  21  of the pin sleeve  2 ′. This causes the pin sleeve  2 ′ to be pulled by an amount of the misalignment, and the split sleeve  40  moves in the same direction. As a result, the split sleeve  40  is increased in diameter due to inclination of the tapered portion. Consequently, the pipe  1  is crimped and fixed from the inside to be firmly connected. 
         [0103]    In the joint of Embodiment 6, the through hole  1   b  that has previously been formed in the pipe  1  has a minimum diameter to allow a tool such as the wrench  4  to be inserted and turn the stop bolt  3  that has been put in the screw hole  16  of the connecting inset portion  12 ′. Therefore, the through hole  1   b  that is viewed in an appearance of a pipe-connecting structure is inconspicuous, so that the design is excellent. In the event that the stop bolt  3  comes loose and is backed off, the stop bolt  3  is mechanically and entirely prevented by the pipe  1  from falling out. 
         [0104]    The stop bolt  3  of Embodiment 6 has an entire length including the conical portion  3   a,  which is equal to or slightly more than an entire length of the screw hole  16  of the connecting inset portion  12 ′. 
         [0105]    The hole  21  formed in the front part of the pin sleeve  2 ′ is a tapered hole that follows the shape of the conical portion  3   a  of the stop bolt  3 . Accordingly, the pin sleeve  2 ′ can be easily and reliably pulled by the amount of the misalignment. 
         [0106]    Embodiment 6 has a structure in which the screw hole  16  of the connecting inset portion  12  is formed as close to a base of the connecting inset portion  12 ′ as possible, and is exposed in a more inward position than at least an inner end of the split sleeve  40 . 
         [0107]    Although the invention has been described above with reference to the embodiments illustrated in the drawings, the invention is not thus limited but is susceptible of design changes, and other modifications and application, which are made by those skilled in the art as needed.