Abstract:
A device for machining the ends of pipes, having a clamping device ( 6 ) for clamping the pipe in place, having an outer ring ( 9 ) and a shaping insert ( 11 ), in which the shaping insert has two half-rings ( 12, 13 ), which are releasably and resiliently connected to one another by means of at least one screw ( 34 ) and at least one spring ( 35 ). The tool is particularly compact, clean, safe and easy to handle.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to a device for machining the ends of pipes, having a clamping device for clamping the pipe in place, having an outer ring and a shaping insert. 
   In piping work, the end faces of the pipe walls are machined before two pipe ends are welded together. The surfaces of the pipe walls which meet at the weld seam have to run precisely at right angles to the axis of the pipeline, must be free of burrs and must be planar. Depending on the type of weld seam, it may be necessary for the end faces to be beveled or rounded. Pipe-flattening and/or chamfering tools are used for this weld preparation work. At a building site, a large number of pipes with different diameters have to be machined as efficiently as possible. 
   U.S. Pat. No. 5,941,145 has disclosed a tool for machining pipe ends of the generic type. The clamping device for clamping the pipe end in place substantially comprises a continuous, outer mounting ring, a lower shaping insert in the shape of a half ring and an upper shaping insert in the shape of a half ring. The shaping inserts have an annular inner surface with an internal radius which corresponds to the external radius of the pipe which is to be machined. The outer surface of the upper shaping insert and the inner surface of the mounting ring are designed in such a manner that, in the clamped state, a sickle-shaped space is present between the mounting ring and the upper shaping insert. The shaping inserts are successively introduced into and secured in the mounting ring. 
   Working on the basis of this prior art, it is an object of the invention to provide a tool for machining the ends of pipes which can be matched as simply as possible to the different pipe diameters and has a structure which is as simple and compact as possible. 
   SUMMARY OF THE INVENTION 
   The object is achieved by a device for machining the ends of pipes, having a clamping device for clamping the pipe in place, having an outer ring and a shaping insert, in which the shaping insert has two half-rings, which are connected to one another by means of at least one screw and at least one spring. 
   It is advantageous for it to be possible for the pipe end to be clamped in place as gently and simply as possible during the machining. This is achieved by the fact that the half-rings are formed in symmetrical pairs with respect to a center line. The half-rings are supplied in pairs. A piece of metal is used to make a ring with an internal diameter which precisely matches the external diameter of the pipe which is to be machined. Then, this ring is halved along the center line. The half-rings are connected to one another by means of screws and are held under prestress by a spring. This significantly simplifies the insertion of the shaping insert into the outer ring of the machining tool. Incorrect pairings of two half-rings are avoided. 
   It is also advantageous for it to be possible for the pipe end to be clamped in place as simply and accurately as possible at right angles to the pipe line axis. This is achieved by the fact that at least one clamping screw for securing the shaping insert is arranged in the outer ring, and that the half-rings in the outer wall each have a recess for accommodating the clamping screw, the recesses being arranged on a center line which is perpendicular to the center line of the two half-rings. This is also achieved by the fact that the screws for connecting the half-rings are designed as precision shoulder screws. The precision shoulder screws have, over a considerable length of the screw shank, an external diameter which is accurately matched to the internal diameter of the bores provided for them in the half-rings, and in this way guide the half-rings as accurately as possible with respect to one another and effect the most accurate possible orientation of the shaping insert and pipe end with respect to the outer ring of the machining tool. 
   It is also advantageous for it to be possible for the machine tool to be driven by different drive motors. This is achieved by the fact that the tool has a coupling region with a coupling adapter for optionally coupling the machining tool to a differently designed drive motor. With a suitable coupling adapter, the machine can be driven both by a drilling machine, which is connected to the mains voltage, and by a rechargeable battery motor or a pneumatic or hydraulic motor. 
   Furthermore, it is also advantageous for it to be possible for the machine tool to be operated as safely as possible by the operator. This can be achieved by the fact that the tool has a protective strap which is arranged in a plane which is formed by the drive axis and a handle of the drive motor. The protective strap prevents the possibility of the tool being switched on undesirably, for example as a result of the switch being pressed against a table edge. 
   Furthermore, it is advantageous for the machine tool to have the shortest possible overall length. This is achieved by the fact that the feed control comprises a feed nut with internal screw thread, a feed ring with external screw thread, at least one driver pin and a slip ring, in which arrangement, to receive the driver pins, the feed ring and the slip ring have bores which, as seen in the axial direction, are formed half along the feed ring and the slip ring, and the feed nut substantially being of a length which results from the sum of the length of the feed ring and the length of the tool feed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An exemplary embodiment of the invention is described with reference to the figures, in which: 
       FIG. 1  shows a perspective view of a tool for machining the ends of pipes in accordance with the invention, 
       FIG. 2  shows a partially sectional view of the tool shown in  FIG. 1 , 
       FIG. 3  shows a section through the tool shown in  FIG. 1 , 
       FIG. 4  shows a view of a base plate used for the tool shown in  FIG. 1 , 
       FIG. 5  shows a perspective view of a shaping insert used in the tool shown in  FIG. 1 , 
       FIG. 6  shows a section through the shaping insert used in the tool shown in  FIG. 5 , 
       FIG. 7  shows a view of the shaping insert used in the tool shown in  FIG. 5 , 
       FIG. 8  shows a perspective view of an assembly of drive spindle and tool carrier used in the machine shown in  FIG. 1 , 
       FIG. 9  shows a section through the assembly shown in  FIG. 8 , 
       FIG. 10  shows a view of the assembly shown in  FIG. 8 , 
       FIG. 11  shows a perspective view of a special nut, and 
       FIG. 12  shows a perspective view of an adapter ring used in the tool shown in  FIG. 1 . 
   

   DETAILED DESCRIPTION 
     FIG. 1  shows a perspective view of a portable device or tool  1  for machining the ends of pipes. The tool  1  comprises, as seen from the back toward the front, a drive motor  2 , a housing  3 , a feed control  4 , a working region  5  and a clamping device  6 . The tool  1  has an axis X which coincides with the drive axis of the motor  2 . In  FIG. 1 , a drilling tool with a handle  7  and a connection cable  8  is illustrated with the drive motor. In a commercially available drilling tool, the chuck for the drill bit can be unscrewed from the drive shaft and coupled to the housing  3 . As an alternative to the drilling tool with the connection cable  8 , it is also possible to have an electric motor which is powered by a storage battery, or a hydraulically or pneumatically driven motor, coupled to the housing  2 . 
   The clamping device  6  comprises an outer ring  9 , two clamping screws  10  and  15 , which are arranged diametrically opposite one another in the outer ring  9 , and a shaping insert  11 , which has an internal diameter which precisely matches the external diameter of the pipe which is to be machined. A different shaping insert is supplied for each external diameter. The shaping insert comprises two half-rings  12 ,  13 . The half-rings  12 ,  13  are produced and supplied in pairs and are formed symmetrically with respect to a center line Z. 
   A strap  14  is formed on the housing  3 . The strap  14  runs from the housing  3  to the handle  7 . The drive axis X of the motor  2 , the handle  7  and the strap  14  form a plane A. A base plate  16  with a coupling socket  17  is indicated below the housing  3 , parallel to this plane A. The tool  1  can be used with or without base plate as desired, i.e. can be used standing on a support or as a portable and hand-held tool. The protective strap  14  protects the region of the drilling tool in which the main switch is arranged. This ensures that the main switch cannot be switched on unintentionally. This would happen, for example, if the machine  1  were to be removed from the base plate  16  and pressed against a table edge in order to change the clamping device  6  or the tool. 
     FIG. 2  shows a further illustration of the tool shown in  FIG. 1 , seen in the direction of the drive axis X and, in the region of the clamping device  6 , in section perpendicular to the drive axis X. In  FIG. 2 , the tool  1  is illustrated without a pipe, in order to make it easier to see a working tool  18  and a tool carrier  19 . 
     FIG. 3  shows a further illustration of the tool  1 . In this case, the housing  3  is illustrated in section on the drive axis X and as seen from the plane A. In the working region  5 , it is possible to see two apertures  20  at the housing  3 , making it possible to see the working tool  18 . The working tool  18  can be watched by the operator when it is being fitted to the tool carrier  19  and while the pipe-machining tool is operating. In this working region  5 , the housing  1  substantially comprises a wall  21  which delimits a cylindrical chip chamber  22 . In the operating state, that end of the pipe which is to be machined and the working tool  18  are located in the chip chamber  22 . 
   The chip chamber  22  can be closed off by an axially displaceable chamber wall  23 . The chamber wall  23  is substantially produced from a transparent material, for example polycarbonate or acrylic plastic. The result of this is that the chips which are formed when the tool is operating are collected. Because the chamber wall is transparent, it is nevertheless possible to observe the working tool  18  and the machining operation through the apertures  20  when the chamber  22  is closed. The chamber wall  23  can interact with a spring (no shown), in such a manner that, in the operating state, the chamber  22  is held in a closed position by the spring force. This also prevents the possibility of anything inadvertently being introduced into the working region of the chip chamber  22  through the apertures  20 . This ensures both clean and safe working. 
     FIG. 3  also shows the feed mechanism for controlling the feed of the working tool. As seen from the outside inward, the feed control  4  comprises a feed nut  24 , a feed ring  25 , two driver pins  26  and a slip ring  27 . On the inner side, the feed nut  24  has an internal screw thread which interacts with an external screw thread which is formed on the feed ring  25 . The feed nut  24  is arranged in an annular recess in the outer wall of the housing  3 . The feed nut itself cannot be displaced in the axial direction in this recess, but rather is merely arranged so that it can rotate in the radial direction. On the outer side, the feed nut has notches or an embossed structure in order to improve the grip when it is being actuated. The feed nut  24  is also provided with a scale which, together with a fixed reference mark on the housing  3 , indicates the extent of the tool feed. The screw threads of the feed nut  24  and of the feed ring  25  can be designed as acme thread and have a small pitch, so that the feed control can be carried out in a nonpositively locking manner, reproducibly and as accurately as possible. The feed ring  25  is arranged in such a manner that it can be displaced in the axial direction but not rotated in the radial direction on the inner side of the feed nut  24  in the recess on the outer side of the housing  3 . 
   In the feed ring  25  and in the slip ring  27  there are bores which each accommodate an end of the driver pin  26 . The driver pin  26  is movable in a slot, running in the axial direction, in the housing wall. To provide good guidance for the slip ring  27 , it is possible to provide two or more driver pins  26 . The slip ring  27  is mounted on a drive spindle  28 . A tool spindle  29 , which on the front side bears the tool carrier  19  and the working tool  18 , is also arranged on the same drive spindle  28 . The axial movement of the driver pins  26  and of the slip ring  27  therefore effects an axial movement of the working tool  18 , of the tool spindle  29  and of the drive spindle  28 . The bores in the feed ring  25  and in the slip ring  27  are formed in the center, i.e. halfway along. The result of this is a uniform distribution of the forces which act on these parts during operation. The feed nut  24  has an overall length which is substantially no greater than the sum of the length of the feed ring  25  and of the length of the feed required for operation of the tool for machining pipe ends. In this way, the shortest possible overall length of the feed mechanism and therefore of the entire tool is ensured. 
   The ability of the moving parts of the feed mechanism to slide is increased by a surface treatment of the surfaces which rub against one another, for example a coating and/or a special surface hardening. In particular the feed nut  24 , the feed ring  25 , the drive spindle  28 , the tool spindle  29  and the associated sliding-contact bearings are provided with a surface which is able to slide by being coated with a material which promotes sliding, such as for example polytetra-fluoroethylene. This surface treatment allows the machine tool to operate entirely without lubricant. This contributes to clean working at the building site. Nothing has to be oiled or lubricated in the tool, and the working environment is not contaminated by drops of oil.  FIG. 3  also shows how the drive spindle  28  is coupled to a spindle of the drive motor  2  at the rear end. 
   It can also be seen from  FIG. 3 , and more clearly from  FIG. 4 , how the housing  3  has a securing pin  30 , which fits into a recess  31  in the pedestal  17  of the base plate  16 , on the lower side.  FIG. 4  also reveals a further bore  32  in the pedestal  17  for a securing screw. On the upper side, the pedestal  17  has an elevation  33  which serves as a stop and positioning aid for the tool on the pedestal  17 . This ensures stable and reliable securing of the tool  1  to the base plate  16 . The tool can quickly be detached from the base plate  16 , since it is merely necessary to undo one screw. 
     FIGS. 5 ,  6  and  7  show the shaping insert  11  all on its own. The shaping insert  11  comprises two half-rings  12 ,  13 , which are held together by screws  34 . The half-rings  12 ,  13  are made from one piece of metal and are separated by sawing along the center line Z. The screws  34  are designed as precision shoulder screws. The precision shoulder screws  34  fit accurately into the bores provided for them in the half-rings and in this way improve the guidance of the two half-rings  12 ,  13  with respect to one another. Springs  35  are arranged on the shoulders of the screws  34 . The half-rings  12 ,  13  are assembled in pairs and are supplied in pairs together with the tool for machining the ends of pipes. The fact that the half-rings are produced in pairs ensures the highest possible level of precision and reproducibility in the clamping of pipes. One half-ring  12  has a recess  36  for an identification plate. The fact that the half-rings are produced in pairs also results in the most accurate possible matching of the internal diameter of the shaping insert  11  to the external diameter of the pipe which is to be machined. A matching shaping insert is supplied for each pipe external diameter. The fitting and removal of the shaping insert  11  at the building site is facilitated by the fact that the operator only has to fix one set of the shaping insert  11  which has been screwed together. Further cylindrical recesses  37 ,  38  are formed in each half-ring  12 ,  13  on opposite sides, perpendicular to the center axis Z. A clamping screw  10  is screwed through the outer ring  9  in the first recess  37  on the lower side of the clamping device  6 . The first clamping screw  10  and the recess  37  in the first half-ring  13  have screw threads which match one another. On the upper side of the clamping device  6 , the second recess  38  in the second half-ring  12  does not have a screw thread. The second screw  15  is introduced into this recess  38  without a screw thread. The second screw  15  is used primarily to transmit the compressive force to the shaping insert  11 . 
   The center line Z between the half-rings  12 ,  13  runs at an angle of preferably 45° with respect to the plane of the base plate  16 . Although arranging the center line Z perpendicular to the base plate  16  would be optimum with a view to uniform self-centering of the half-rings  12 ,  13  and for good accessibility of the clamping screws  10 ,  15 , in this position the flanks of the screws  10 ,  15  would impede the view and accessibility of the working region  5 . Arranging the center line Z horizontally with respect to the base plate  16  would make access to the lower screw  10  unnecessarily difficult and would influence the self-centering of the two half-rings  12 ,  13 . In order, with the shortest possible length of the tool, to optimize both accessibility to the working region  5  and to the working tool  18  and accessibility to the clamping screws  10 ,  15  of the clamping device  6 , it is advantageous for the center line Z to be arranged at an angle of approximately 45°. 
     FIGS. 8 ,  9  and  10  illustrate the combination of working tool  18 , tool carrier  19 , tool spindle  29  and drive spindle  28 . The tool carrier  19  is arranged displaceably in a groove  39  in the front side of the tool spindle  29 . The tool carrier  19  has an elongate aperture  40  in order to allow the tool carrier  19  to be displaced over the length of the aperture  40 . The tool carrier  19  is secured to the tool spindle  29  by means of a screw  41  which is guided through the aperture  40 . This continuous displaceability of the tool carrier  19  ensures that the working tool  18  can be utilized over its entire length. The working tool  18  itself is designed as what is known as a disposable tip with a plurality of cutting edges and can therefore be used a number of times by turning the sides. 
     FIG. 10  shows a view of the drive spindle  28  as seen in the direction of the drive axis X. On the side of the drive motor  2 , the drive spindle  28  has a recess  42 , into which a nut  43  made from brass, which is illustrated in  FIG. 11 , fits. The nut  43 , which is screwed onto the drive shaft of the drive motor, and the recess  42  are in this case, by way of example, of square design, but may also be in the form of any other regular polygon. In the region of the nut  43 , both the force from the motor is transmitted to the working tool and the axial feed of the working tool with respect to the drive shaft of the motor  2  is produced. The nut  43  in each case has an internal screw thread which matches the external screw thread of the drive shaft of the corresponding drive motor. The nut  43  is used to introduce the drive shaft of the drive motor as far as possible into the recess  42  and into the housing  3 . This arrangement of nut  43  and recess  42  results in the shortest possible overall length of the housing  3 . 
     FIG. 12  shows a perspective view of an adapter ring  44 . The adapter ring can be arranged between the housing  3  and the drive motor  2  and is used mainly to adapt to the different diameters of the drive unit. By means of the adapter ring  44  and the special nut  43  which fits into the recess  42 , the housing  3  can if necessary also be coupled to other drive motors, such as for example a battery-driven drill screwdriver or a hydraulically or pneumatically driven motor.