Patent Abstract:
Provided is a bushing device capable of improving a tight-fitting structure in which a bushing is tightly pushed into a water-communicating hole. A bushing collar is placed between the bushing and an inner wall of the water-communicating hole. An outer surface of the bushing is tapered, and an inner surface of the bushing collar is tapered in accordance with the outer surface of the bushing. When the bushing is secured to the water-communicating hole, the bushing collar is tightly fit into the water-communicating hole as a result of the wedge-shaped effect exerted between the tapered surfaces of the bushing and the bushing collar. Since the tapered surface of the bushing and the bushing collar are tightly fit, it is possible to significantly improve a heat-conductive efficiency between the bushing and the bushing collar, and reducing procedures needed to exchange casings with a good usability.

Full Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0001]    The present invention relates to a bushing device, a water-communicating mechanism and a method of making the water-communicating mechanism in which an aqueous medium (coolant) is supplied to a water-communicating hole (cooling hole) which is formed on a device body or a metal die to cool the device body or the metal die. 
         [0002]    In a first prior art reference (Japanese Laid-open Patent Application No. 2006-289382), disclosed is a metal die cooling structure and a method of making the metal die cooling structure in which a heat-conductive layer is provided between a casing inserted into a cooling hole and an inner wall of the cooling hole. The heat-conductive layer is filled with a molten metal (referred to as a filler metal hereinafter) having a low melting temperature. 
         [0003]    More specific, a soldering material (alloyed metal having a low melting temperature) is provided between an outer surface of the casing and an inner surface of the cooling hole so as to obviate an air clearance therebetween. After the alloyed metal is cooled and solidified, the alloyed metal resultantly fixes the casing within the cooling hole (refer to paragraph [0012]). 
         [0004]    In a second prior art reference (Japanese Laid-open Patent Application No. 09-29416), disclosed is a molten-metal cooling pin used for a metal die in which an inner cylinder and an outer cylinder are provided in a double cylinder structure within a molten-metal cooling portion of the metal die. 
         [0005]    More particularly, the outer cylinder is made of an alloy tool steel, and the inner cylinder is made of a copper-based alloy or a stainless steel. 
         [0006]    In this instance, the inner cylinder is press fit into the outer cylinder through their inner and outer surfaces by means of a shrinkage-fit or cooling-fit procedure (refer to paragraph [0007]). 
         [0007]    The second prior art reference also discloses a tight-fitting heat-conductive layer in which a molten metal is solidified after the molten metal is poured into the air clearance between the inner cylinder and the outer cylinder. 
         [0008]    In general, since the metal die has a cavity into which the molten metal (e.g., molten aluminum) is poured, the metal die is subjected to a thermal shock due to an abrupt temperature rise. On the other hand, the metal die is subjected to a quick temperature drop caused by an evaporation heat of a separable agent applied to the metal die before separating a female die from a male die. This may cause numerous cracks (referred also to as “die cracks” hereinafter) appeared on the cavity of the metal die. 
         [0009]    The cooling hole formed on the metal die collects a cooling medium (e.g., cooling water) which causes a rust appeared to erode the metal die. The rust together with the thermal shock facilitates to further develop the die cracks. When the die cracks develop such a degree as to communicate with the cavity, products which are made by pouring the molten metal into the cavity deteriorate their quality to an unacceptable level. 
         [0010]    In order to prevent the cracks from occurring on the cavity, the casing and the inner cylinder (equivalent to the internal lining) are provided as mentioned in the first and second prior art references. 
         [0011]    In the first prior art reference in which the molten metal is poured into the cooling hole to improve the tight-fitting structure between the casing and the cooling hole, it requires a heating procedure to heat the metal die at a temperature (e.g., 600° C.) more than the filler metal can melt when the filler metal is taken out of the metal die upon exchanging the casings (refer to paragraph [0019]). Namely, it is necessary to implement the procedure to melt and solidify a proper amount of the filler metal so as to obviate the air clearance, thereby making the procedure laborious and time-consuming (not user-friendly). 
         [0012]    Upon implementing the maintenance of removing strains from the metal die, there would be a risk at the time of heating the filler metal that the filler metal will be molten to release the tight-fitting structure between the casing and the cooling hole. When the casing tightly engages against the inner wall of the cooling hole, there is a possibility of developing the die cracks and the casing being partly broken to resultantly lose the function of the internal lining. 
         [0013]    The second prior art reference which is represented by the tight-fitting heat-conductive layer in the molten-metal cooling pin used for the metal die, has the same problems as mentioned in the first prior art reference. 
         [0014]    The second prior art reference discloses a simplified structure in which the inner cylinder (made by a copper-based alloy or stainless steel) is press fit into the outer cylinder. Due to the spring-back phenomenon when press fitting the inner cylinder into the outer cylinder with an elastic deformation accompanied, there would be a possibility that the inner cylinder will not completely engage with the outer cylinder, which causes to reduce a heat-conductive efficiency between the two cylinders. This makes it difficult to favorably control the temperature of the metal die when cooling the metal die. 
         [0015]    Therefore, the present invention has been made with the above drawbacks in mind, it is a main object of the invention to provide a bushing device, a water-communicating mechanism and a method of making the water-communicating mechanism which are capable of achieving a tight-fitting structure between a device body and an inner wall of a water-communicating hole with a simplified structure. 
       SUMMARY OF THE INVENTION 
       [0016]    According to the present invention, there is provide a bushing device in which a bushing is provided on a device body to be in communication with a water-communicating hole, so that an aqueous medium is supplied to the bushing. A bushing collar is placed between the bushing and an inner wall of the water-communicating hole, and a diametrical dimension of the bushing collar is arranged to be identical to a diameter of the water-communicating hole when the bushing is secured to the water-communicating hole. An outer surface of the bushing is tapered, and an inner surface of the bushing collar is tapered in accordance with the outer surface of the bushing. 
         [0017]    The device body categorically includes the metal die, an engine and the equivalents. The metal die categorically includes a molten-metal cooling pin (e.g., the outer cylinder in the prior art) which directly comes in contact with molten metal. This is because the molten-metal cooling pin has a cooling hole to constitute a part of the metal die upon implementing the die-casting procedure. 
         [0018]    Namely, the bushing device may be inserted into the cooling hole defined on the molten-metal cooling pin. The metal die categorically includes a molten-metal pouring device placed on a stationary side of the metal die and a sub-flowing device placed on a movable side of the metal die. Namely, the bushing device may be inserted into the cooling hole provided on the metal die or the sub-flowing device. 
         [0019]    According to other aspect of the invention, the bushing device has the bushing collar formed by a material which is higher in thermal conductivity and ductility compared to a ferrous steel. It is preferable to select the material from aluminum, copper and the equivalents. 
         [0020]    According to other aspect of the invention, the bushing collar is divided into a plurality of collar parts cut along a longitudinal direction. 
         [0021]    More specific, the bushing collar is longitudinally cut at a maximum diameter of the bushing collar to make divided parts readily insert into the water-communicating hole. Plurality means more than two elements, and the bushing collar may be divided into three or four parts. The divided parts may be bonded at their front ends by means of a welding procedure. 
         [0022]    According to other aspect of the invention, the bushing collar is formed to have notched portions extended from a basal portion to a proximity of a front end portion of the bushing collar, and the front end portion is formed into a thinned or notched configuration. 
         [0023]    According to other aspect of the invention, the bushing has a cylindrical body and a flange portion secured to an open-ended portion of the cylindrical body by means of a welding procedure such as, for example, a brazing or soldering procedure. The cylindrical body may be formed integral with the flange portion by means of the metal die. 
         [0024]    According to other aspect of the invention, the bushing has a cylindrical body and a flange portion. The flange portion is removably mounted on an open-ended portion of the cylindrical body. The flange portion may be removably mounted on the cylindrical body through a hermetic sealing means such as, for example, a sealant, O-ring or screw. 
         [0025]    According to other aspect of the invention, a hooking means is mounted on the open-ended portion of the cylindrical body. The hooking means is represented by a screw by way of illustration. 
         [0026]    According to other aspect of the invention, a deformable filler is provided between the bushing and the water-communicating hole. The deformable filler is represented by a metallic paste such as, for example, metallic fibers, zinc or the equivalents. The deformation categorically includes phenomena when the metallic fiber plastically deforms, and the metallic paste flows. 
         [0027]    According to other aspect of the invention, there is provided a water-communicating mechanism in which a bushing is provided on a device body to be in communication with a water-communicating hole, so that an aqueous medium is supplied to the bushing. The bushing has an outer surface tapered. A bushing collar has an inner surface tapered in accordance with the outer surface of the bushing, and placed between the bushing and the water-communicating hole. A diametrical dimension of the bushing collar is arranged to be identical to a diameter of the water-communicating hole after the bushing is secured to the water-communicating hole. A water-communicating means is secured to the bushing to continuously supply an aqueous medium to the bushing. 
         [0028]    According to other aspect of the invention, a first deformable filler is provided between the bushing and an inner wall of the water-communicating hole, or a second deformable filler is provided between the bushing and the bushing collar. 
         [0029]    The first deformable filler and the second deformable filler may be appropriately inserted into the air clearance casually appeared on the metal die. 
         [0030]    According other aspect of the invention, there is provided a method of making a water-communicating mechanism in which a bushing is provided on a device body to be in communication with a water-communicating hole, so that an aqueous medium is supplied to the bushing. A bushing collar is inserted into the water-communicating hole. An inner surface of the bush collar is tapered, and a diametrical dimension of the bushing collar is identical to a diameter of the water-communicating hole. The bushing collar is inserted into the bushing. The bushing has an outer surface tapered in accordance with the inner surface of the bush collar. The bushing is pushed into the water-communicating hole by a predetermined depth so that the bushing collar is tightly fit against an inner wall of the water-communicating hole. 
         [0031]    According to other aspect of the invention, a water-communicating means is provided after the end of the tightly pushing step so as to continuously supply an aqueous medium to the bushing, and a water-communicating step is further provided to form a communication passage by means of the water-communicating means. 
         [0032]    The water-communicating step signifies a procedure of connecting a water source (e.g., a faucet of waterworks) through the water-communicating means. Alternatively, the water-communicating step signifies a procedure of flowing a heat-exchanged water to an exhaust basin so as to form a water flow passage (equivalent to a cooling circuit). 
         [0033]    According other aspect of the invention, at least either one of a first filling step before the end of inserting the bushing collar, or a second filling step is provided before the end of inserting the bushing. A first deformable filler is inserted at the first filling step, and a second deformable filler is inserted at the second filling step. 
         [0034]    Such is the structure that the bushing is pushed into the water-communicating hole by a predetermined depth so that the bushing collar is spread to tightly fit against an inner wall of the water-communicating hole. Due to the wedge-shaped effect of tapered surface in which the bushing pushes to spread the bushing collar, the bushing collar is brought to interpose between the bushing and the water-communicating hole with the bushing collar tightly engaged with the inner wall of the water-communicating hole. The bushing collar serves as an internal lining, and the bushing collar positively isolates the bushing from the inner wall of the water-communicating hole. 
         [0035]    With a combination structure in which the bushing makes its tapered surface fit with the tapered surface of the bushing collar, it becomes possible to tightly engage the bushing with the inner wall of the water-communicating hole through the bushing collar. This makes it possible to control the temperature of the device body (e.g., metal die) without losing a high heat-conductive efficiency. 
         [0036]    With a simplified mechanical structure in which the bushing makes its tapered surface fit with the tapered surface of the bushing collar, it makes the structure more labor-saving and convenient to use at the time of implementing the maintenance when exchanging the casings, compared to the prior art counterpart in which the molten metal is poured into the air clearance appeared on the cooling hole and the runner cooling pin. 
         [0037]    With the simplified mechanical structure in which the bushing makes the bushing collar tightly engage with the inner wall of the water-communicating hole when inserting the bushing into the water-communicating hole, it becomes possible to obviate the spring-back phenomenon to strengthen the tight-fitting structure, as opposed to the prior art counterpart in which the inner cylinder is press fit into the outer cylinder. 
         [0038]    Because the bushing collar positively isolates the bushing from the inner wall of the water-communicating hole, it is possible to keep the bushing off the water-communicating hole, thereby preventing the aqueous medium from seeping into the water-communicating hole even when the die cracks occur on the metal die. 
         [0039]    Upon removably mounting the flange portion on the cylindrical body, it becomes possible to insert the cylindrical body into the water-communicating hole even if the flange portion is non-concentric with the cylindrical body and the water-communicating hole. This makes it possible to quickly assemble the flange portion to the cylindrical body and the water-communicating hole. 
         [0040]    By obviating the need of concentrically aligning the cylindrical body with the cylindrical body and the water-communicating hole, and also obviating the need of using a welding jig to prevent the cylindrical body from being unfavorably deformed, it is possible to readily reduce the bushing device into mass production. 
         [0041]    By mounting the flange portion on the cylindrical body through the hermetic sealing means, it is possible to tightly engage the flange portion with the cylindrical body, thereby positively preventing a water leakage between the flange portion and the cylindrical body. By attaching the hooking means on the open-ended portion of the cylindrical body, it becomes possible to easily take the cylindrical body out of the water-communicating hole by catching the hooking means with a special tool. 
         [0042]    By inserting the deformable filler into the air clearance between the bushing and the bushing collar, it render unnecessary to demand exact dimensional sizes for the bushing and the water-communicating hole, thereby making it easy to check and control the products. 
         [0043]    By inserting the metallic paste such as, for example, the metallic fibers and zinc into the air clearance between the bushing and the bushing collar, it is possible to prevent the rust from occurring on the bushing and the bushing collar, while improving the heat-conductive efficiency therebetween. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0044]    A preferred form of the present invention are illustrated in the accompanying drawings in which: 
           [0045]      FIG. 1  is a schematic view of a water-communicating mechanism according to an embodiment of the invention; 
           [0046]      FIG. 2  is a longitudinal cross sectional view of a water-communicating hole in the water-communicating mechanism; 
           [0047]      FIG. 3  is a longitudinal cross sectional view of a bush collar which is inserted into the water-communicating hole; 
           [0048]      FIG. 4  is a longitudinal cross sectional view of a bushing which is inserted into the bushing collar installed in the water-communicating hole; 
           [0049]      FIG. 5  is a longitudinal cross sectional view of a bushing secured to the metal die by means of a lock nut; 
           [0050]      FIG. 6  is a longitudinal cross sectional view of the bushing in which the lock nut is tightened by a predetermined amount of turns; 
           [0051]      FIG. 7  is a side elevational view of a coupler pipe; 
           [0052]      FIGS. 8-10  are longitudinal cross sectional views of a part of the bushing collar according to modification forms A-C of the invention; 
           [0053]      FIGS. 11-17  are exploded cross sectional views of the bushing according to modification forms D-I of the invention; 
           [0054]      FIG. 18  is a longitudinal cross sectional view of a filler which is inserted into the water-communicating hole according to a modification form K of the invention; 
           [0055]      FIG. 19  is a longitudinal cross sectional view of the filler which is inserted between the bushing and the bushing collar; 
           [0056]      FIG. 20  is a plan view of a flange portion according to a modification form M of the invention; 
           [0057]      FIG. 21  is a side elevational view of the flange portion; 
           [0058]      FIG. 22  is a longitudinal cross sectional view of the flange portion which is secured by means of the lock nut; and 
           [0059]      FIG. 23  is a plan view of the bushing device which is mounted on an engine. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0060]    In the following description of the depicted embodiments, the same reference numerals are used for features of the same type. Positions and directions of the various members are used to correspond to right-left sides, and up-down sides of the attached drawings throughout each embodiment of the invention. 
         [0061]    Referring to  FIGS. 1 through 7  which shows a bushing device, a water-communicating mechanism and a method of making the water-communicating mechanism, the bushing device serves as a cooling type bushing device  10 , and the water-communicating mechanism serves as a metal die cooling mechanism S according to an embodiment of the invention. 
         [0062]    A metal die  80  is incorporated into the metal die cooling mechanism, and categorically covered by a device body as an item to be cooled. As shown in  FIGS. 1 and 2 , the metal die  80  has a cavity side  81 A which configures the item to be cast, and having a die side  81 B placed opposite to the cavity side  81 A to have a cooling hole  82  cylindrically formed as a water-communicating hole. 
         [0063]    At an upper end portion of the cooling hole  82 , a female thread portion  83  is circumferentially provided as clearly shown in  FIG. 2 . From the female thread portion  83  downward, the downward hole  82 A is consecutively provided. An inner diameter of the female thread portion  83  is identical to an inner diameter D 1  of the downward hole  82 A. The cooling hole  82  has a bottomed portion which is defined as a semi-spherical portion  82 B. 
         [0064]    As shown in  FIG. 1 , the metal die cooling mechanism S has the cooling type bushing device  10  and a lock nut  22 , the latter of which positively places the bushing device  10  in position within the cooling hole  82 . A coupler pipe  24  is connected to the bushing device  10 . The bushing device  10  together with the coupler pipe  24  partly forms a water communication passage (equivalent to a cooling circuit) which continuously supplies and drains a coolant as an aqueous medium (water-communicating medium). 
         [0065]    As shown in  FIG. 4 , the cooling type bushing device  10  is a combination of a cooling type bushing collar  12  and a cooling type bushing  14 . The cooling type bushing collar  12  serves as a bushing collar which can be merely referred to as a collar hereinafter. The collar  12  and the bushing  14  are configured in accordance with contours of the cooling hole  82 . The collar  12  is cut along a longitudinal direction to be divided into two symmetrical parts as shown at phantom lines in  FIG. 2 . 
         [0066]    The collar  12  is cut in a manner to divide a maximum diameter (equivalent to a diametrical portion) of the collar  12  into a pair of collar pieces  12 A,  12 B cut along the longitudinal direction. 
         [0067]    When the collar  12  is inserted in the cooling hole  82 , a gap distance T 1  appears between longitudinal sides of the collar pieces  12 A,  12 B as shown at solid lines in  FIG. 3 . For this reason, each of the collar pieces  12 A,  12 B is shaven at the diametrical portion by half of the gap distance T 1  along their longitudinal sides. 
         [0068]    The collar  12  is preferably made by pressing a metallic material such as, for example, copper and aluminum which are higher in both heat-conductivity and ductility compared to a ferrous steel metal. By making the identical collar pieces  12 A,  12 B by means of a pressing procedure, it is possible to manufacture the collar  12  with a lower cost. 
         [0069]    After the collar  12  and the cooling type bushing  14  are each inserted into the cooling hole  82 , the collar  12  forms a cylindrical configuration having a bottomed portion which aligns along an axial line P of the cooling hole  82  as shown at dot-dash lines in  FIG. 2 . A leading portion of the collar  12  is configured in conformity with the semi-spherical portion  82 B of the cooling hole  82 . 
         [0070]    Namely, a leading end of the collar  12  forms a semi-spherical end portion  12 C as shown in  FIG. 4 . The collar  12  has a length L which is somewhat smaller than a total length of the downward hole  82 A and the semi-spherical portion  82 B as shown in  FIG. 3 . 
         [0071]    A diametrical dimension of the collar  12  is arranged to be identical to the inner diameter D 1  of the downward hole  82 A when the cooling type bushing  14  is secured to the cooling hole  82  as shown in  FIG. 6 . 
         [0072]    As shown at the phantom lines in  FIG. 2 , the collar  12  has an outer surface aligned along the axial line P. The collar  12  is arranged to bring the outer surface into tight-fitting engagement with an inner surface of the cooling hole  82 . Instead of the word of tight-fitting engagement, the word of engagement is used as the same meaning hereinafter unless particularly specified. 
         [0073]    In the meanwhile, as shown in  FIG. 4 , an inner surface of the collar  12  forms a tapered surface  12 D which slants against the axial line P. The collar  12  has a thickness which progressively increases as approaching the semi-spherical end portion  12 C from an insert opening  13  which serves as an open end of the collar  12 . For this reason, the tapered surface  12 D inclines against the axial line P from the insert opening  13  to the semi-spherical end portion  12 C. This means that the collar  12  has the inner surface configured to be tapered off toward the semi-spherical end portion  12 C. By way of illustration, the collar  12  is bored so that the tapered surface  12 D has a gradient by a rate of 1/200. 
         [0074]    As shown in  FIG. 4 , the cooling type bushing  14  has a bottom-ended cylindrical body  16  and a flange portion  18 , the latter of which is secured (fixedly attached) to an open end  17  of the cylindrical body  16  by means of welding procedure (e.g., soldering means). The cylindrical body  16  serves as an internal lining of the water-communicating mechanism. 
         [0075]    As shown in  FIG. 5 , the flange portion  18  has an insert portion  19  and which is to be in communication with the open end  17  of the cylindrical body  16 . The flange portion  18  also has a circumferential portion, around which a male thread portion  20  is provided to be diametrically greater than the insert portion  19 . The flange portion  18  makes its male thread portion  20  tightened into the female thread portion  83  of the cooling hole  82 . 
         [0076]    It is to be noted that the outer diameter of the insert portion  19  is somewhat smaller than an inner diameter of the open end  17 , so that the flange portion  18  can be inserted into the cylindrical body  16 . 
         [0077]    The flange portion  18  has a hexagonal wrench hole  18 A, to which the Allen wrench (a.k.a. a hexagonal wrench, but not shown) is applied. The wrench hole  18 A lies in registration with the male thread portion  20 . Under the wrench hole  18 A, the flange portion  18  has a female thread portion  18 B to be in communication with the wrench hole  18 A. The female thread portion  18 B is adapted to mesh with a male thread portion  34 A which is provided on an outer surface of the coupler pipe  24  as shown in  FIG. 1 . 
         [0078]    It is noted that a welded portion in which the flange portion  18  is bonded to the cylindrical body  16  is located at an outer surface of the cylindrical body  16  in registration with the insert portion  19 . 
         [0079]    The cylindrical body  16  has a straight portion  16 A, a tapered surface  16 B and a semi-spherical bottom  16 C as shown in  FIG. 5 . The straight portion  16 A which secures the flange portion  18 , equi-diametrically extends by a length L 2  from the open end  17  of the cylindrical body  16  as shown in dot-dash lines in  FIG. 5 . 
         [0080]    The tapered surface  16 B works to pushingly spread the collar pieces  12 A,  12 B against an inner surface of the cooling hole  82 . The semi-spherical bottom  16 C is to be in registration with the semi-spherical end portion  12 C of the collar  12 . The cylindrical body  16  is integrally formed by a high-tension steel metal sheet such as, for example, a mild steel metal by means of the pressing procedure. 
         [0081]    It is noted that the cylindrical body  16  may be formed by means of a boring procedure or swaging procedure, in lieu of the pressing procedure. 
         [0082]    The tapered surface  16 B formed at an inner surface of the cylindrical body  16 , is tapered away in accordance with the tapered surface  12 D of the collar  12  as observed by dot-dash lines Y which extends downward from the straight portion  16 A in  FIG. 4 . The tapered surface  16 B renders its inner diameter somewhat greater that an inner diameter of the tapered surface  12 D of the collar  12 . 
         [0083]    This is because the tapered surface  12 B is pushingly spread to be brought into tight-fitting engagement with an inner wall (i.e., inner surface) of the cooling hole  82  upon inserting the cooling type bushing  14  into the collar  12 . 
         [0084]    As shown in  FIG. 6 , a lock nut  22  is provided to mesh with the female thread portion  83  of the cooling hole  82 , so as to prevent the male thread portion  20  from being inadvertently loosened. The lock nut  22  has a hexagonal wrench hole  22 A formed similar to the wrench hole  18 A of the flange portion  18 . 
         [0085]    For this reason, it is possible to concurrently secure the lock nut  22  and the cooling type bushing  14  to the cylindrical body  16  by putting the wrench into the two holes  18 A,  22 A at the same time. 
         [0086]    As shown in  FIG. 7 , the coupler pipe  24  serves as a water-communicating means, and having a supply connector  28  which continuously supplies a coolant (e.g., aqueous medium, water) to the cooling type bushing  14 . Connected to the supply connector  28  is a supply pipe  30 . 
         [0087]    A drainage connector  32  is to guide the heat-exchanged drain water to an exhaust basin (not shown). Connected to the drainage connector  32  is a water-chute pipe  34 . To the supply connector  28 , a water-communicating pipe (not shown) is connected which comes from a water source (e.g., faucet of waterworks). The coupler pipe  24  extends the supply pipe  30  to a proximity of a semi-spherical bottom portion  16 D of the cylindrical body  16  as shown in  FIG. 1 . 
         [0088]    Into the wrench holes  18 A,  22 A, a columnar support pipe  26  is inserted to be held upright as shown in  FIG. 1 . The water-chute pipe  34  which is located under the support pipe  26 , is diameter-reduced more than the support pipe  26 . To an outer surface of the water-chute pipe  34 , a male thread portion  34 A is formed. The support pipe  26  is formed into a circular cylinder, so that the support pipe  26  is inserted into and extended through the wrench holes  18 A,  22 A. 
         [0089]    A method of making the metal die cooling mechanism S is described as a method of assembling the metal die cooling mechanism S. 
         [0090]    At a collar-insert step, the collar  12  is inserted into the cooling hole  82 . At a bushing-insert step, the cooling type bushing  14  is inserted into the collar  12  placed within the cooling hole  82 . 
         [0091]    At a tight-fitting step (tightly fitting step), the cooling type bushing  14  is pushed further into the cooling hole  82  to assemble the cooling type bushing device  10 . After assembling the cooling type bushing device  10 , the coupler pipe  24  is installed to the cooling type bushing device  10  at a water-communicating step, so as to finish the assemble of the metal die cooling mechanism S. 
         [0092]    At the collar insert step as shown at the phantom lines in  FIG. 3 , the collar  12  is inserted into the cooling hole  82  with the collar pieces  12 A,  12 B joined together, so as to make the collar pieces  12 A,  12 B engaged with the inner wall of the cooling hole  82 . 
         [0093]    According to the embodiment of the invention, the collar pieces  12 A,  12 B are formed by dividing the collar  12  into two parts, and the collar pieces  12 A,  12 B are shaven at the longitudinal sides. This makes the outer diameter of the joined pieces  12 A,  12 B smaller than the inner diameter of the cooling hole  82 , thereby making it possible to readily insert the collar  12  into and take the collar  12  out of the cooling hole  82 . This also prevents the inner wall of the cooling hole  82  from being injured at the time of inserting the collar  12  into and take the collar  12  out of the cooling hole  82 . 
         [0094]    At the bushing insert step as shown in  FIG. 4 , the cooling type bushing  14  is placed at the insert opening  13  of the collar  12 , and tighten the male thread portion  20  around the female thread portion  83  with the use of the Allen wrench (not shown). 
         [0095]    In this situation, the lock nut  22  is tightened to push the cooling type bushing  14  until the lock nut  22  makes its head surface in flush with the die surface  81 B of the metal die  80  as shown in  FIG. 5 . 
         [0096]    At the time when the lock nut  22  occupies the flush position, a clearance appears between an apex of the semi-spherical bottom  16 C and an innermost concave portion of the semi-spherical end portion  12 C as designated at a predetermined distance L 3  in  FIG. 5 . 
         [0097]    At the tight-fitting step as shown in  FIG. 6 , the cooling type bushing  14  is further inserted by the distance L 3 , the lock nut  22  sinks by the distance L 3  under the die surface  81 B. This makes the collar  12  (collar pieces  12 A,  12 B) pushingly spread and tightly engage with the inner wall (i.e., circumferential wall) of the cooling hole  82 . 
         [0098]    Namely, the cooling type bushing  14  pushes the collar  12  deeper against the inner wall of the cooling hole  82 , while at the same time, guiding the tapered surface  16 B along the tapered surface  12 D of the collar  12  as shown in  FIG. 4 . 
         [0099]    It is to be noted that in order to locate the cooling type bushing  14  in position at a predetermined place as shown in  FIG. 6 , only the lock nut  22  may be further tightened. 
         [0100]    The collar  12  which is pushingly spread against the inner wall of the cooling hole  82 , is divided into the collar pieces  12 A,  12 B as shown in  FIG. 3 . The collar  12  can be made of the copper metal which is higher in both heat-conductivity and ductility compared to the ferrous steel metal. This makes the collar pieces  12 A,  12 B elastically deformable to obviate the gap distance T 1  to tightly join the collar pieces  12 A,  12 B together. 
         [0101]    At the time of pouring the molten metal into the cavity of the metal die  80 , the metal die  80  is heated to rise its temperature. Because the collar  12  thermally expands more than both the metal die  80  and the cooling type bushing  14 , the collar pieces  12 A,  12 B elastically deforms to tightly join the collar pieces  12 A,  12 B together all the more. 
         [0102]    With the result that the cooling type bushing  14  pushingly spreads the collar  12  due to the wedge-shaped effect, the effect brings the collar  12  into tight engagement with the inner wall of the cooling hole  82 . This makes it possible to attain the tight-fitting structure between the bushing device  10  and the cooling hole  82  with a simplified construction. 
         [0103]    With the collar  12  separating the cooling type bushing  14  from the inner wall of the cooling hole  82 , it is possible for the collar  12  to prevent the cooling type bushing  14  from being directly in contact with the inner wall of the cooling hole  82 . This makes it possible to avoid the aqueous medium from leaking off the cooling type bushing  14  to the cooling hole even when the die cracks occur on the metal die  80 . 
         [0104]    With a combined structure that the cooling type bushing  14  engages its tapered surface  16 B with the tapered surface  12 D of the collar  12 , it becomes possible to tightly engage the bushing device  10  with the inner wall of the cooling hole. This makes it possible to achieve a high heat-conductive efficiency therebetween, which is quite favorable when controlling the temperature of the metal die  80 . 
         [0105]    With the tight-fitting structure simplified between the bushing device  10  and the cooling hole  82 , it becomes possible to exchange the bushing devices with less laborious and less time-consuming procedure compared with the prior art counterpart which interposes the molten metal between the cooling hole and the molten-metal cooling pin. 
         [0106]    Such is the structure that upon inserting the cooling type bushing  14  into the cooling hole  82 , the cooling type bushing  14  tightly engages its tapered surface  12 D against the inner wall of the cooling hole  82 . This makes it possible to mitigate the spring-back phenomenon, thereby maintaining the tight-fitting structure for an extended period of time, as opposed to the prior art counterpart in which the inner cylinder is press fit into the outer cylinder by means of the shrinkage-fit or cooling-fit procedure. 
         [0107]    At the water-communicating step, the coupler pipe  24  is attached to the cooling type bushing  14  after the end of the tight-fitting procedure. 
         [0108]    Namely, upon mounting the coupler pipe  24  on the cooling type bushing  14 , the supply pipe  30  is inserted into the cooling type bushing  14  as shown in  FIG. 1 . At the same time, the support pipe  26  is inserted into the wrench hole  18 A,  22 A of the lock nut  22 . Thereafter, the coupler pipe  24  brings its male thread portion  34 A to mesh with the female thread portion  18 B of the flange portion  18 , thereby concurrently preventing the aqueous medium from leaking off the support pipe  26 . 
         [0109]    In order to complete the water-communicating conduit, the supply connector  28  is attached to the spigot of the waterworks (not shown) through a communication pipe (not shown), and the drainage connector  32  is led to a catchment basin through a communication pipe (not shown). 
         [0110]    The tapwater from the waterworks is continuously supplied to the cylindrical body  16  of the cooling type bushing  14  through the supply connector  28  and the supply pipe  30 , and drained to the catchment basin through the water-chute pipe  34  and the drainage connector  32  as shown at an arrow in  FIG. 1 . 
         [0111]    During the process in which the tapwater is supplied as the aqueous medium to the cooling type bushing  14 , the tapwater cools the metal die  80  through the cooling type bushing  14  when the molten-metal is poured into the cavity. The water heat-exchanged with the die metal is drained outside through the water-chute pipe  34 . 
         [0112]    As shown in  FIGS. 8-10 , it is to be noted that the collar  12  may be integrally formed in one piece, in lieu of dividing it into two collar pieces  12 A,  12 B. 
         [0113]    In a first modification form A depicted in  FIG. 8 , a notched portion  38  is formed along the axial direction of the collar  12 . The notched portion  38  extends from the insert opening  13  to the proximity of the apex of the semi-spherical end portion  12 C. 
         [0114]    The apex of the semi-spherical end portion  12 C may be formed into a thickness-reduced configuration as designated by a thickness-reduced connection  40  in  FIG. 8 . The thickness-reduced connection  40  is smaller in thickness by ⅓ than the semi-spherical end portion  12 C. 
         [0115]    Upon inserting the collar  12  into the cooling hole  82 , the collar  12  flexes its basal portion, thereby making it readily to insert the collar  12  into and take the collar  12  out of the cooling hole  82 . The integrally formed collar  12  prevents the collar  12  from being advertently lost, as opposed to the case in which the collar  12  is divided into the collar pieces  12 A,  12 B. 
         [0116]    In a second modification form B depicted in  FIG. 9 , the thickness-reduced connection  40  serves as a kerf  42  which is V-shaped in cross section. 
         [0117]    The kerf  42  has a depth dimension which is equivalent to one-third of the thickness measured at the apex of the semi-spherical end portion  12 C. In the second modification form B, the same advantages are achieved as accomplished in the first modification form A. 
         [0118]    In a third modification form C depicted in  FIG. 10 , the leading end portions (apexes) of the collar pieces  12 A,  12 B are bonded together to form a bonded connection  44  by means of such as, for example, the welding procedure. 
         [0119]    The bonded connection  44  has a thickness dimension which is equivalent to one-third of the thickness measured at the apex of the semi-spherical end portion  12 C. In the third modification form C, the same advantages are achieved as accomplished in the first modification form A. 
         [0120]      FIGS. 11 and 12  respectively show modification forms D and E represented by the cooling type bushing  14  in  FIG. 5 . 
         [0121]    In the modification form D depicted in  FIG. 11 , an extension pipe  46  is provided to connect between the flange portion  18  and the cylindrical body  16 . 
         [0122]    This is because the extension pipe  46  is used when the cooling type bushing  14  is greater in length than the cooling hole  82  in  FIG. 1 . The extension pipe  46  is fixedly connected to each of the flange portion  18  and the cylindrical body  16  by means of the welding procedure. The other structure than the extension pipe  46  is the same as described in the embodiment of  FIG. 4 , describing the identical structure is omitted. 
         [0123]    In the modification form E depicted in  FIG. 12 , a criss-cross groove  48  is provided on an upper surface of the flange portion  18 . The criss-cross groove  48  is used when screwing the cooling type bushing  14  into the cooling hole  82 . 
         [0124]    In this instance, in lieu of the wrench hole  18 A in  FIG. 5 , a circular hole may be provided which is in communication with the female thread portion  18 B of the flange portion  18 . The other structure than the criss-cross groove  48  is the same as described in the embodiment of  FIG. 4 , describing the identical structure is omitted. 
         [0125]      FIGS. 13 and 14  respectively show modification forms F and G represented by the cooling type bushing  14  in  FIG. 5 . In both the modification forms F and G, the flange portion  18  is removable mounted on the cylindrical body  16 . 
         [0126]    The modification forms F and G are employed to the case in which the flange portion  18  defies to concentrically align in the cylindrical body  16  when the flange portion  18  is bonded to the cylindrical body  16  by means of the welding procedure (e.g., soldering or brazing procedure) as observed in the preceding embodiment. 
         [0127]    In the modification form F depicted in  FIG. 13 , an upper end of the cooling type bushing  14  has an outer flange  16 D in perpendicular to the axial direction integrally formed upon drawing the cooling type bushing  14 . The outer flange  16 D is placed such as not to interfere in the female thread portion  83  of the cooling hole  82 . 
         [0128]    In the flange portion  18  of the insert portion  19 , the insert portion  19  determines its outer diameter somewhat greater than an inner diameter of the straight portion  16 A of the cylindrical body  16 . 
         [0129]    Into an outer surface of the insert portion  19 , an annular sealant  50  is inserted as a hermetic sealing means. The sealant  50  which is slightly greater in axial length than the insert portion  19 , is provided by molding a synthetic resin by way of illustration. 
         [0130]    The sealant  50  has an inner diameter which is slightly smaller than an outer diameter of the insert portion  19 . For this reason, the sealant  50  is fixedly installed on the flange portion  18  to tightly fit against the insert portion  19  and the flange portion  18 . 
         [0131]    Namely, the sealant  50  is fixedly pressed against the outer flange  16 D of the cylindrical body  16 , while at the same time, a lower side of the insert portion  19  comes in contact with the outer flange  16 D. This makes it possible to air-tightly seal between the flange portion  18  and the outer flange  16 D, thereby preventing the coolant (aqueous medium) from leaking through therebetween. 
         [0132]    With the flange portion  18  removably mounted on the cylindrical body  16 , it is possible to insert the cooling type bushing  14  into the cooling hole  82  even when the flange portion  18  defies to concentrically align in the cylindrical body  16 . This also makes it possible to readily assemble the flange portion  18  to the cylindrical body  16 . 
         [0133]    The above structure enables users to obviate the concentrically aligning procedure against the cylindrical body  16 , while at the same time, removing the need of handling a welding jig to prevent the cylindrical body from being unfavorably deformed, it is possible to readily reduce the cooling type of bushing  14  into mass production with an improved efficiency. The other structure than the removably mounting components is the same as described in the embodiment of  FIG. 5 , describing the identical structure is omitted. 
         [0134]    It is further to be noted that the sealant  50  may be determined to be smaller in axial length than the insert portion  19 , so that the insert portion  19  can be dimensionally determined to be insertable into an inner surface of the cylindrical body  16 . 
         [0135]    In the modification form G depicted in  FIG. 14 , the cooling type of bushing  14  makes an O-ring  52  place around an outer surface of the insert portion  19 . On the outer surface of the insert portion  19 , a circumferential groove is provided into which the O-ring  52  is interfit. The insert portion  19  together with the O-ring  52  is inserted into (i.e., connected to) the cylindrical body  16 . 
         [0136]    In this situation, it is to be noted that the outer flange  16 D can be omitted from the cylindrical body  16 . The other structure than the O-ring  52  and the groove is the same as described in the modification form F, describing the identical structure is omitted. 
         [0137]    In the modification form H depicted in  FIG. 15 , the flange portion  18  is removably mounted on the cylindrical body  16  by means of a screw component provided as the hermetic sealing means. 
         [0138]    As mentioned in the modification forms depicted in  FIGS. 13 and 14 , the modification form H makes it possible to insert the flange portion  18  into the cylindrical body  16  even when the flange portion  18  does not concentrically align with the cylindrical body  16 . 
         [0139]    In the modification form H, a screw collar  54  is welded as a reinforcement to an inner side of the straight portion  16 A (open-ended portion  17 ) of the cylindrical body  16 . The screw collar  54  is formed into an annular configuration, and having an inner surface which is formed into a female thread portion  54 A to serve as a hooking means. 
         [0140]    On an outer surface of the insert portion  19 , a male thread portion  18 C is provided which meshes with the female thread portion  54 A, so as to resultantly secure the flange portion  18  to the cylindrical body  16  through the screw collar  54  as shown in  FIG. 16 . 
         [0141]    The screw collar  54  has an outer diameter determined to be slightly greater than an inner diameter of the straight portion  16 A. The screw collar  54  press fits its outer surface circumferentially into an upper end portion of the straight portion  16 A as shown at phantom lines in  FIG. 15 . Weldment is applied entirely to a press fitting area between the screw collar  54  and the straight portion  16 A by means of the welding procedure. 
         [0142]    With the screw collar  54  press fit into the cylindrical body  16 , it is possible to minimize the deformation caused by the thermal influence, to which the cylindrical body  16  is subjected due to the welding procedure (fixing means). 
         [0143]    Thereafter, the cylindrical body  16  is inserted into the cooling hole  82 , and then the flange portion  18  is secured to the screw collar  54  by meshing the male thread portion  18 C with the female thread portion  54 A. 
         [0144]    In this situation, a heat-resistant sealant (not shown) may be applied to the male thread portion  18 C or the female thread portion  54 A to hold an air-tightness therebetween. 
         [0145]    In the modification form H, such is the structure that the flange portion  18  is inserted into the cylindrical body  16  through the screw collar  54 . This makes it possible to omit the axially aligning procedure between the flange portion  18  and the cylindrical body  16 , thereby enabling the users to improve an assemble efficiency when reduced to mass production. 
         [0146]    Upon meshing the male thread portion  18 C with the female thread portion  54 A, the Allen wrench (not shown) is applied to the hexagonal hole  18 A as observed in  FIG. 16 . The other structure than the screw collar  54  and the male thread portion  18 C is the same as described in the modification forms F and G, describing the identical structure is omitted. 
         [0147]    It is to be noted that the flange portion  18  may be provisionally welded to the cylindrical body  16 . 
         [0148]    In this instance, the flange portion  18  is welded at four locations at regular intervals (e.g., 90 degrees) to the outer surface of the cylindrical body  16 , the locations of which correspond to the insert portion  19 . 
         [0149]    Even with the provisional welding procedure applied to the cylindrical body  16 , it is sufficient to fixedly secure the flange portion  18  to the cylindrical body  16 , while minimizing the unfavorable deformation due to the welding procedure. The screw collar  54  may be used to the cylindrical body  16  formed integral with the outer flange  16 D. 
         [0150]      FIG. 17  shows a modification form I of the cooling type bushing  14  in which the flange portion  18  is removably mounted on the cylindrical body  16 . A female thread portion  16 E is directly formed on the inner surface of the straight portion  16 A to serve as a part of the hermetic sealing means. 
         [0151]    The insert portion  19  has an outer diameter corresponding to the female thread portion  16 E. The outer surface of the insert portion  19  has the male thread portion  18 C (referred to  FIG. 15 ) to serve as a part of the hermetic sealing means or the hooking means. 
         [0152]    The flange portion  18  brings the male thread portion  18 C to mesh with the female thread portion  16 E upon securing the flange portion  18  to the cylindrical body  16 . In this situation, the heat-resistant sealant (not shown) may be applied to the male thread portion  18 C or the female thread portion  16 E to hold the air-tightness therebetween. The sealant  50  as observed in  FIG. 13  may be used to a basal end of the insert portion  19 . 
         [0153]    In order to take the cylindrical body  16  out of the cooling hole  82 , the flange portion  18  is first taken from the cylindrical body  16  by applying the Allen wrench to the hexagonal hole  18 A (refer to  FIG. 15 ). Then, a special tool  90  (knock-release tool) is used to take the cylindrical body  16  out of the cooling hole  82 . The special tool  90  has a slidable weight which produces an impact when slid along a rail (not shown) to release an item (cylindrical body  16 ) to be taken out. 
         [0154]    The special tool  90  has a male thread portion  90 A meshed with the female thread portion  16 E. By sliding the weight, the impact enables the users to readily release the cylindrical body  16  out of the cooling hole  82 . 
         [0155]    When the flange portion  18  is fixedly secured to the cylindrical body  16  by means welding procedure as shown in  FIG. 5 , the special tool  90  brings the male thread portion  90 A to mesh with the female thread portion  18 B, in order to take the flange portion  18  out of the cooling hole  82 . It is noted that any hook portion will be usable so long as it can be caught with a detachment tool. The other structure than the special tool  90  is the same as described in the modification form H, describing the identical structure is omitted. 
         [0156]    In a modification form K depicted in  FIGS. 18 and 19 , a filler is provided entirely at a first clearance between the collar  12  and the cooling hole  82 , or the filler is provided entirely at a second clearance between the collar  12  and the cooling type bushing  14  as an air-bleeding action. This is to ameliorate the heat-conductive efficiency between the collar  12  and the cooling hole  82 , or between the collar  12  and the cooling type bushing  14 . By way of illustration, a bundle of a metallic fibers  60  available in market or a certain amount of a metallic paste  62  is used as the filler. 
         [0157]    The metallic fibers  60  (around 50 μm in diameter) are made from metals combined with titanium, copper and brass. The metallic paste  62  has a granulated zinc (around 96% of a total) and a non-combustible epoxy resin as a rust-resistant material. Zinc has a tendency to ionize and oxidize in preference to iron. An oxide film formed on zinc prevents the rust from appearing thereon. Zinc also has a heat-conductivity higher than that of iron (equivalent to that of copper), and less soluble than aluminum. For this reason, zinc is well-suited to fill the clearances with the filler. The filler categorically includes a metallic powder (e.g., granulated copper). 
         [0158]    In the modification form K depicted in  FIG. 18 , the first clearance is filled with the metallic fibers  60  or the metallic paste  62  between the cooling hole  82  and the collar  12 . Then, the second clearance is filled with the metallic fibers  60  or the metallic paste  62  between the cooling type bushing  14  and the collar  12 . The metallic fibers  60  or the metallic paste  62  deforms in accordance with the shape of the clearances to fully load the clearances because the metallic fibers  60  plastically displaces and the metallic paste  62  evenly flows. In case of the metallic paste  62 , the paste  62  may be molded by means of a sintering procedure. 
         [0159]    An amount of the metallic fibers  60  and an amount of the metallic paste  62  may be altered under different circumstances. The metallic fibers  60  and the metallic paste  62  may be employed in combination or singularity. The filler may be applied only to one of the first clearance and the second clearance. Alternatively, the filler may be applied both of the first clearance and the second clearance. 
         [0160]    The filler is deformable that the filler loads the clearances with the metallic fibers  60  (metallic paste  62 ) in accordance with the shape of the clearances. This allows a latitude in precision to the cooling type bushing device  10  and the cooling hole  82 , thereby rendering it easy to maintain and control the products. The filler makes it possible to improve the heat-conductive efficiency while preventing the rust from appearing thereon. 
         [0161]    In a modification form M depicted in  FIGS. 20 and 21 , the flange portion  18  and the lock nut  22  are deformed to prevent the flange portion  18  from being inadvertently loosened. The flange portion  18  forms a hook head  21  on the upper surface of the male thread portion  20 . The hook head  21  has straight portions  21 A and tapered portions  21 B, the latter of which are consecutively formed from a peripheral portion of the straight portions  21 A. The hook head  21  is determined to be diametrically smaller than the male thread portion  20 . 
         [0162]    The hook head  21  is linearly notched at both sides to form a pair of the straight portions  21 A, so that the straight portions  21 A can be caught by a spanner (tightening tool). The tapered portions  21 B position between the opposed straight portions  21 A, and extend from an outer periphery of the hook head  21  toward the male thread portion  20 , so as to form an arc-shaped configuration. 
         [0163]    As shown at broken lines in  FIG. 21 , the flange portion  18  forms a circular hole  21 C diametrically greater than the female thread portion  18 B, and designed to be in communication with the female thread portion  18 B. To the circular hole  21 C, the support pipe  26  of the coupler pine  24  (refer to  FIG. 5 ) is to be inserted. 
         [0164]    As shown in  FIG. 22 , a lock nut  70  is provided to be diametrically identical to the male thread portion  20  of the flange portion  18 . The lock nut  70  has a wrench hole  70 A to which the Allen wrench is applied, while at the same time, the wrench hole  70 A is formed to guide the support pipe  26  to pass through. 
         [0165]    The lock nut  70  has a lock surface  70 C located to face the flange portion  18 . The lock surface  70 C has an outer peripheral portion flared to entirely engage with the tapered portion  21 B so as to form a tapered surface  70 B. 
         [0166]    With an outer side of the lock nut  70 , a male thread portion  70 D is provided to mesh with the female thread portion  83  of the cooling hole  82 , as is the case with the male thread portion  20  of the flange portion  18 . 
         [0167]    The lock nut  70  engages its lock surface  70 C with the flange portion  18 , and brings the tapered surface  70 B into tight engagement with the tapered portions  21 B of the hook head  21  when the lock nut  70  is tightened. 
         [0168]    In the modification form M, the cooling type bushing  14  is first inserted into the cooling hole  82 . Then, the spanner is applied to the straight portions  21 A in order to turn the lock nut  70  to place the cooling type bushing  14  in position in the cooling hole  82 . 
         [0169]    With the use of the Allen wrench, the lock nut  70  presses the flange portion  18  and resultantly brings its male thread portion  70 D into engagement with the female thread portion  83  of the cooling hole  82 . 
         [0170]    In the modification form M, the double-nut action exerts between the male thread portion  20  and the male thread portion  70 D, while the wedge-shaped effect works between the tapered portion  21 B and the tapered surface  70 B. 
         [0171]    Due to the double-nut action and the wedge-shaped effect, it is possible to further prevent the flange portion  18  (i.e., cooling type bushing  14 ) from being loosened. 
         [0172]    The device body categorically includes the metal die (shown in the preceding embodiment) and an engine. 
         [0173]    In a three-cylinder type engine  86  depicted in  FIG. 23 , it is considered to be structurally difficult to cool a central cylinder  87 B among the three cylinders  87 A- 87 C. In order to overcome the difficulty, a plurality of the cooling type bushing devices may be convergently located around the central cylinder  87 B. 
         [0174]    In this instance, water jackets  88  are placed at both sides to straddle the cylinders  87 A- 87 C. This enables the users to cool the cylinder  87 B not only by the water jackets  88  but also by the plurality of the cooling type bushing devices. The water coolant may be circulated either through one-way or two-way path. 
         [0175]    The device body also includes a central processing unit (CPU) of a super computer, a capacity of which is such as to require one floor of a building to accommodate. Namely, the cooling type bushing device  10  is applicable to the central processing unit (CPU) which serves as the device body. 
         [0176]    In the meanwhile, the cooling type bushing device  10  is also employed not only to cool the device body but also to pre-heat the device body. By way of example, a certain amount of hot water (e.g., 100° C.) may be circulated within the cooling type bushing device  10 . 
         [0177]    The metal die categorically includes a molten-metal cooling pin (equivalent to the prior art outer cylinder) which comes in direct contact with the molten metal. 
         [0178]    The cooling pin has a cooling path and constitutes a part of the metal die when used to the die-casting procedure. The cooling type bushing device  10  may be inserted into the cooling path of the cooling pin. 
         [0179]    The metal die includes a molten-metal pouring device placed on a stationary side of the metal die and a sub-flowing device placed on a movable side of the metal die. Namely, the bushing device may be inserted into a cooling passage provided on the metal die or the sub-flowing device. 
         [0180]    In the molten-metal pouring device which is subjected to an abrupt temperature rise (thermal fluctuation), and the cooling hole  82  is obturated with the cooling type bushing  14  by means of a lid, it is preferable to employ the cooling type bushing  14  in which the cylindrical body  16  and the flange portion  18  are integrally bonded by means of the welding procedure or the like. 
         [0181]    It is to be noted that a gradient of the tapered surface  12 D may be changed to any desired degrees (e.g., 1/150) depending on usage. The collar  12  may be divided into a plurality of collar pieces (e.g., 3-4 pieces) other than the two collar pieces  12 A,  12 B. 
         [0182]    The cooling type bushing  14  may be completely mounted on the cooling hole  82  at any position in which the flange portion  18  meshes the male thread portion  20  with the female thread portion  83 . At the same time, the provisional welding may be used to prevent the flange portion  18  from being loosened. The water heat-exchanged at the cooling type bushing device  10  may be cooled down to reuse as a circulation system. 
         [0183]    The collar  12  may be cast by means of the sintering procedure with the copper powder (granulated copper) heated within a die. The flange portion  18  may be formed integral with the cylindrical body  16  to produce the cooling type bushing  14 . 
         [0184]    The tapered surface  12 D of the collar  12  and the tapered surface  16 B of the cylindrical body  16  may be formed straight. In this case, the clearances are loaded with the metallic fibers  60  or metallic paste  62 . 
         [0185]    Among the preceding embodiment and the modification forms A-K thus far mentioned, two or more examples may be combined. 
         [0186]    While several illustrative embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Such variations and alternate embodiments are contemplated, and can be made without departing from the spirit and scope of the invention as defined in the appended claims.

Technology Classification (CPC): 8