As a disclosure of the NC automatic lathe of this type, there is Patent Document 1, for example. For information, Patent Document 1 belongs to the applicant of this patent application.
Patent Document 1: JP-A-10-015702
The NC automatic lathe having such a configuration as shown in FIG. 7 is disclosed in the above mentioned Patent Document 1. In the first place, there is arranged a headstock 103 provided with a main spindle 101. This headstock 103 is so configured as to move in a direction of Z1 axis which is parallel to an axial direction of the main spindle. A guide bush 105 is arranged in front of the main spindle 101, and holds a tip end portion of a work 107 which is holded by the main spindle 101.
A back attachment 109 is arranged so as to be opposed to the main spindle 103. This back attachment 109 is provided with a sub spindle 111, and is so configured as to move in a direction of Z3 axis which is parallel to the axial direction of the main spindle 101. A gang tool post 113 is arranged at a side of the guide bush 105, and is so configured as to move in both directions of X1 axis and Y1 axis which are perpendicular to the axial direction of the main spindle 101 and also perpendicular to each other.
A turret tool post 115 is arranged at another side of the guide bush 105, opposite to the gang tool post 113. This turret tool post 115 is provided with a turret 117, and is so configured as to move in a direction of Z2 axis which is parallel to the axial direction of the main spindle 101, and in both directions of X2 axis and Y2 axis which are perpendicular to the direction of the Z2 axis and also perpendicular to each other.
The turret 117 is provided with a plurality of tool holder attaching parts 119, and tool holders which hold tools (not shown) will be detachably attached to the tool holder attaching parts 119. Moreover, a plurality of tools 121 are attached to the gang tool post 113.
According to the above described configuration, front machining is conducted on the work 107 which is holded by the main spindle 101, by means of the tools 121 of the gang tool post 113 and the tools (not shown) attached to the turret tool post 115. After the front machining has been finished, cutting-off work is conducted, and then, back machining is conducted on the work 107 which is holded by the sub spindle 111, by means of the turret tool post 115.
In case of the NC automatic lathe having the above described configuration, the back machining on the work 107 has been conducted only by the turret tool post 115 which has been also concerned with the front machining. Accordingly, there has been such a problem that the turret tool post 115 must cover a larger number of machining processes as compared with the gang tool post 113 which is concerned with only the front machining, and it would be impossible to properly distribute the machining processes between the front face and back face thereby to reduce a machining time. Moreover, there has been a problem that because the turret tool post 115 need to be provided with the tools for both the front machining and the back machining, and there is a shortage of tools in number, for conducting complicated and diversified machining. Further, for simultaneously conducting both primary machining and secondary machining, the turret tool post 115 can be concerned with the front machining only with the limited tools, and so, the front machining is conducted only by the gang tool post. In this case, complicated machining cannot be applied even to the front machining, and it would be impossible to reduce the machining time, by simultaneously machining, using the two tool rests.
Under the circumstances, an NC automatic lathe having such a configuration as shown in FIG. 8 has been proposed. This is the configuration of the NC automatic lathe of “TNL-26” model, manufactured by Traube GmbH, in Germany.
In the first place, there is arranged a headstock 203 provided with a main spindle 201. This headstock 203 is so configured as to move in a direction of Z axis which is parallel to an axial direction of the main spindle 201. Aback attachment 205 is arranged so as to be opposed to the headstock 203. This back attachment 205 is provided with a sub spindle 207, and is so configured as to move in the direction of the Z axis.
A front machining tool unit 209 is arranged at a side of the back attachment 205. This front machining tool unit 209 is provided with a plurality of front machining tools 211, and is so configured as to move in the direction of the Z axis. Moreover, both the back attachment 205 and the front machining tool unit 209 are so configured as to move also in the direction of X axis.
A turret tool post 213 and a turret tool post 215 are arranged at both sides of the main spindle 201. The turret tool post 213 is provided with a turret 217, and is so configured as to move in directions of the X axis, Y axis and Z axis. A plurality of tool holders 219 are detachably attached to the turret 217, and tools 221 are attached to the tool holders.
The turret tool post 215 is provided with a turret 223, and is so configured as to move in directions of the X axis and Y axis. A plurality of tool holders 225 are detachably attached to the turret 223, and tools 227 are attached to the tool holders.
Moreover, a back machining tool unit 229 is arranged at a side of the main spindle 201. A plurality of back machining tools 231 are attached to this back machining tool unit 229. The back machining tool unit 229 is so configured as to move in the directions of the X axis and Y axis.
According to the NC automatic lathe having the above described configuration, because there are provided the turret tool post 213 and the turret tool post 215, and additionally, the front machining tool unit 209 is provided, the three tool rests will be simultaneously concerned with the front machining, even though both primary and secondary machining are simultaneously conducted. Accordingly, it is possible to rapidly perform complicated machining on the front face. Further, the back machining is conducted by the back machining tools 231 attached to the back machining tool unit 229 and the back machining tools attached to the turrets 217, 223. As compared with the NC automatic lathes as shown in FIG. 7, the back machining is conducted by the back machining tools 231 attached to the back machining tool unit 229 independently from the front machining, whereby the machining time can be reduced.