Horizontal hobbing machine with chip conveyor

Abstract: A horizontal hobbing machine comprises a cutting section (22,23,25,26,27,34) provided on the bed (21) a hob (27) and a horizontal rotary shaft (34) carrying the work gear (24). A chip conveyor (31) is provided below the bed (21). No coolant is supplied to the cutting section during the cutting process, hence the gear teeth are generated by dry-cutting. Chips produced during hobbing drop onto the conveyor by their own weight, i.e. by gravity. The conveyor (31) may transport chips which have dropped onto it, for example, out of the machine.

Description: The present invention relates to a dry-cutting horizontal hobbing machine according to the preamble of claim 1. A hobbing machine for machining a gear by cutting is a typical machine tool for machining a gear. Hobbing machines are classified into a vertical hobbing machine for cutting a tooth form in a work supported around a central shaft provided substantially vertical, and a horizontal hobbing machine for cutting a tooth form in a work supported around a central shaft provided substantially horizontal. An example of the conventional horizontal hobbing machine will now be described with reference to FIGS. 1 to 3. As is shown in FIGS. 1 to 3, a headstock 2 and a tailstock 3 are slidably supported on a bed 1. A work piece 4 is rotatably supported around a horizontal situated shaft between the headstock 2 and tailstock 3. On the other hand, a saddle 5 is slidably supported on the bed 1. A head 6 is supported on the saddle 5. A hob 7 of a high speed tool steel is supported on the head 6. The hob 7 is rotated by a main shaft motor 8. The head 6 is provided with a coolant nozzle 9. A coolant is supplied to a cutting section from the coolant nozzle 9. A chip exhaust groove 10 is provided on the bed 6. The groove 10 is provided with an exhaust port 11 inclined rearward of the present machine (horizontal hob machine: bed 1). Controls necessary for generating a tooth form, e. g. rotation of work piece 4, rotation and radial feed of hob 7, etc., are effected on the basis of commands form a control board 12. In the above-described hobbing machine, while the work piece 4 is being rotated, the hob 7 is driven by the main shaft motor 8. The hob 7 and work piece 4 are thus engaged and a tooth form is generated on and outer periphery of the work piece 4. In this case, the rotating hob 7 is radially fed to the work piece 4 by sliding the saddle 5, thereby generating a predetermined tooth form on the work piece 4. During the cutting process, a coolant is supplied to the cutting section from the coolant nozzle 9, thus lubrication and cooling the cutting section and washing away produced cut chips. The chips washed away with the coolant form the cutting section flow through the chip exhaust groove 10 on the bed 6 along with the coolant, and is drained out of the machine (horizontal hob machine: bed 1) from the exhaust port 11 to be recovered. In the field of hobbing machines, too, various improvements have been made in order to enhance productivity and to reduce manpower. In addition, in these years, there is a demand for taking measures to protect environment. A measure for protection environment in the field of hobbing machines is a so-called "dry-cutting" in which cutting is performed without using a coolant. The use of the coolant not only deteriorates the working environment due to malodor or dispersion, but also causes air pollution due to treatment of waste oil. Main problems to be solved in adopting the dry-cutting in the filed of hobbing machines are wear of the hob and disposal of chips. The wear of the hob can be reduced, for example, by substituting a hob of cemented carbide for the hob 7 of hight speed tool steel. DE 295 07 871 U1 discloses a horizontal hobbing machine comprising a single conveyor for exhausting cut chips in a direction parallel to the axis direction of the shaft. Lederberger A.: "Einfluss der Marktforderungen auf die Konstruktion von Drehmaschinen" discloses a metal working lathe comprising a single conveyor. As regards the disposal of chips, however, there is no satisfactory measure, and this is the most serious problem in the dry-cutting. If the coolant is used, the chip are washed away with the coolant and exhausted out of the machine (horizontal hobbing machine: bed 21). In the dry-cutting using no coolant, however, chips will remain and accumulate in respective parts of the hobbing machine. Consequently, the chips will be caught among the sliding parts or operating parts of the hobbing machine, and normal operations will be hindered. Moreover, heat of chips is transmitted to the respective parts of the hobbing machine, resulting in thermal deformation and deterioration in machining precision. The object of the present invention is to provide a horizontal hobbing machine capable of efficiently disposing of chips even in the dry-cutting. The object of the invention is achieved by a horizontal hobbing machine according to claim 1. According to this horizontal hobbing machine, no coolant is supplied to the cutting section during the cutting process, and a tooth form is generated by dry-cutting. Chips produced by the cutting drop onto the conveyor by their own weight. The chips which have dropped are conveyed by the conveyor and exhausted, for example, out of the machine. If the horizontal hobbing machine according to the invention is applied to the product line, it enables various processing for maintenance, including exhausting of cut chips, to be carried efficiently. This is because the horizontal hobbing machine according to the invention includes a conveyor having a direction of conveyance, which is perpendicular to the axial direction of the rotary shaft. This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: FIG. 1 is a front view of a conventional horizontal hobbing machine; FIG. 2 is a plan view of the conventional horizontal hobbing machine; FIG. 3 is a side view of the conventional horizontal hobbing machine; FIG. 4 is a front view of a horizontal hobbing machine according to a first embodiment of the present invention; FIG. 5 is a plan view of the horizontal hobbing machine according to the first embodiment of the invention; FIG. 6 is a side view of the horizontal hobbing machine according to the first embodiment of the invention; FIG. 7 is a front view of a horizontal hobbing machine according to a second embodiment of the present invention; FIG. 8 is a plan view of the horizontal hobbing machine according to the second embodiment of the invention; FIG. 9 is a side view of the horizontal hobbing machine according to the second embodiment of the invention; FIG. 10 is a front view of a horizontal hobbing machine according to a third embodiment of the present invention; FIG. 11 is a plan view of the horizontal hobbing machine according to the third embodiment of the invention; and FIG. 12 is a side view of the horizontal hobbing machine according to the third embodiment of the invention. Preferred embodiments of a horizontal hobbing machine according to the present invention will now be described with reference to the accompanying drawings. As is shown in FIGS. 4 to 6, a cutting unit is disposed on the bed 21. The cutting unit includes at least a horizontal rotary shaft and a hob. The cutting unit generates a tooth form on the work supported around the rotary shaft by means of the hob. The cutting unit comprises a headstock 22, a tailstock 23, a saddle 25, a head 26, a hob 27, a main shaft motor 28 and a rotary shaft 34. The cutting unit will now be described. The headstock 22 and tailstock 23 are slidably supported on the bed 21. The work 24 is rotatably supported around the horizontal rotary shaft 34 between the headstock 22 and tailstock 23. On the other hand, the saddle 25 is slidably supported on the bed 21. A head 26 is supported on the saddle 5. The hob 27 of, e.g. cemented carbide is supported on the head 26. The hob 27 is rotated by the main shaft motor 28. Controls necessary for generating a tooth form, e.g. rotation of work 24, rotation and radial feed of hob 27, etc., are effected on the basis of commands from a control board 29. An opening 30 is formed in the bed 21 in a region below the cutting unit where chips drop. A chip conveyor 31 is provided below the cutting unit including the opening 30. The chip conveyor 31 is moved in a direction along the rotational axis of the work 24 (an axis of the rotary shaft 34), i.e. in the rightward direction (direction of arrow) in FIGS. 4 and 5. In the present machine of the invention, i.e. the horizontal hobbing machine, a front side and a rear side thereof are defined. The front side of the machine is a side on which the headstock 22 and tailstock 23 of the cutting unit are disposed on the bed 21, and the rear side of the machine is a side on which the saddle 25 and control board 29 are disposed on the bed 21 and a maintenance space (not shown) is provided. In the above-described hobbing machine, while the work 24 is being rotated, the hob 27 is driven by the main shaft motor 28. The hob 27 and work 24 are thus engaged and a tooth form is generated on an outer periphery of the work 24. In this case, the rotating hob 27 is radially fed to the work 24 by sliding the saddle 25, thereby generating a predetermined tooth form on the work 24. During the cutting machining, no coolant is supplied to the cutting unit, and the tooth form is generated by dry-cutting. All chips produced by the cutting drop on the conveyor 31 through the opening 30 by their own weight. The chips which have dropped are conveyed in a direction along the rotational axis of the work 24 (the axis of the rotary shaft 34), i.e. in the rightward direction (direction of arrow) in FIGS. 4 and 5. Accordingly, even if dry-cutting is performed, chips are efficiently disposed of. No chips remain and accumulate on the respective parts of the hobbing machine. Besides, there arise no problems due to chips being caught among the sliding or operating parts of the hobbing machine, i.e. hindrance of normal operation, and degradation in machining precision resulting from thermal deformation due to heat of chips transmitted to the respective parts of the hobbing machine. A second embodiment of the invention will now be described with reference to FIGS. 7 to 9. In FIGS. 7 to 9, the elements common to those shown in FIGS. 4 to 6 are denoted by like reference numerals, and a description thereof is omitted. In the second embodiment, an opening 30 is formed in the bed 21 in a region below the cutting unit where chips drop. A chip conveyor 31 is provided below the cutting unit including the opening 30. The chip conveyor 31 is moved in a direction along the rotational axis of the work 24 (the axis of the rotary shaft 34), i.e. in the rightward direction (direction of arrow) in FIGS. 4 and 5. Another chip conveyor 32 is provided so as to be continuous with a terminal end portion of the chip conveyor 31. The chip conveyor 32 is moved in a direction (upward direction in FIG. 8; rightward direction in FIG. 9; indicated by an arrow) perpendicular to the rotational axis of the work 24 (the axis of the rotary shaft 34), that is, in the rearward direction of the present machine (horizontal hobbing machine: bed 21). The terminal end of conveyance of chip conveyor 31 and the beginning end of conveyance of chip conveyor 32 are positioned to spatially cross each other so that chips conveyed by the chip conveyor 31 may drop from the terminal end of conveyance of the conveyor 31 onto the chip conveyor 32. The terminal end of conveyance of chip conveyor 32 is located on the rear side of the present machine (horizontal hobbing machine: bed 21). A maintenance space is normally provided on the rear side of the machine (horizontal hobbing machine: bed 21). In the horizontal hobbing machine of this embodiment having the above structure, chips produced by the cutting process drop onto the chip conveyor 31 from the opening 30 by their own weight and are conveyed by the conveyor 31 in the rightward direction in FIGS. 7 and 8 of the present machine (horizontal hobbing machine: bed 21). The chips conveyed by the chip conveyor 31 then drop onto the chip conveyor 32 at the terminal end of conveyance of the conveyor 31. The chips are conveyed by the conveyor 32 to the maintenance space on the rear side of the machine (horizontal hobbing machine: bed 21) and discharged out of the machine. Accordingly, even if the dry-cutting is performed, the chips are efficiently disposed of. In addition, the chips are conveyed by the chip conveyors 31 and 32 to the maintenance space on the rear side of the machine (horizontal hobbing machine: bed 21), and maintenance is facilitated. Moreover, since the chips are discharged from the rear side of the machine (horizontal hobbing machine: bed 21), the horizontal hobbing machine can be laid out with less limitations and this is advantageous. A third embodiment of the invention will now be described with reference to FIGS. 10 to 12. In FIGS. 10 to 12, the elements common to those shown in FIGS. 4 to 9 are denoted by like reference numerals and a description thereof is omitted. An opening 30 is formed in the bed 21 in a region below the cutting unit where chips drop. A chip conveyor 33 is provided below the cutting unit including the opening 30. The chip conveyor 33 is moved in a direction (upward direction in FIG. 8; rightward direction in FIG. 9; indicated by an arrow) perpendicular to the rotational axis of the work 24 (the axis of the rotary shaft 34), that is, in the rearward direction of the present machine (horizontal hobbing machine: bed 21). The chip conveyor 33 is formed wide in the direction of the rotational axis of the work 24 (the axis of the rotary shaft 34) so as to cover the cutting unit. A maintenance space is normally provided on the rear side of the machine (horizontal hobbing machine: bed 21). In the horizontal hobbing machine of this embodiment having the above structure, chips produced by the cutting process drop onto the chip conveyor 33 from the opening 30 by their own weight and are conveyed by the single conveyor 33 to the maintenance space on the rear side of the machine (horizontal hobbing machine: bed 21) and discharged out of the machine. Accordingly, even if the dry-cutting is performed, the chips are efficiently disposed of. In addition, the chips are conveyed by the single chip conveyor 33 to the maintenance space on the rear side of the machine (horizontal hobbing machine: bed 21), and maintenance is facilitated. Moreover, since the chips are discharged from the rear side of the machine (horizontal hobbing machine: bed 21), the horizontal hobbing machine can be laid out with less limitations and this is advantageous. As has been described above, according to the horizontal hobbing machine of this invention for cutting a tooth form on the work supported around a substantially horizontal central shaft, the conveyor for conveying chips is provided in a lower part of the machine (horizontal hobbing machine: bed 21) below the cutting section. Thus, even if the dry-cutting is performed, chips are discharged by the conveyor and efficiently disposed of. Therefore, no chips remain and accumulate on the respective parts of the hobbing machine, and there arise no problems due to chips being caught among the sliding or operating parts of the hobbing machine, i.e. hindrance of normal operation, and degradation in machining precision resulting from thermal deformation due to heat of chips transmitted to the respective parts of the hobbing machine.

Claims: A dry-cutting type horizontal hobbing machine comprising: a bed (21); a dry-cutting section (22, 23, 25, 26, 27, 28, 34) provided on said bed (21) and including at least a horizontal rotary shaft (34) and a hob (27), said dry-cutting section (22, 23, 25, 26, 27, 28, 34) generating a tooth form on a work piece supported around said horizontal rotary shaft (34) by means of said hob (27), so as to perform dry cutting; and a belt conveyor section (31, 32) being provided in a lower part of said dry-cutting section (22, 23, 25, 26, 27, 28, 34) below said bed (21) for exhausting cut chips from said drying-cutting section (22, 23, 25, 26, 27, 28, 34), characterized in that said belt conveyor section (31, 32) comprises a first conveyor (31) for conveying the cut chips in a direction parallel to the axis direction of said shaft (34), and a second conveyor (32) for receiving cut chips from said first conveyor (31) and conveying the cut chips in a direction of conveyance which is perpendicular to an axial direction of said rotary shaft (34); and said bed (21) has an opening (30) beneath said dry-cutting sections (22, 23, 25, 26, 27, 28, 34) and having a first opening dimension, in a direction along the axial direction of said shaft, which is larger than a second opening dimension, in a direction along the direction of conveyance of said first conveyor (31). A dry cutting type horizontal hobbing machine according to claim 1 characterized in that the belt conveyor section (31, 32) comprises a first conveyor (31) for conveying the cut chips in a direction parallel to the axis direction of the shaft (34), and a second conveyor for receiving cut chips from the first conveyor (31) and conveying the cut chips in a direction of conveyance which is perpenicular to the axial direction of the horizontal rotary shaft (34); the first conveyor (31) has a beginning end of conveyance located below the dry cutting section (22, 23, 25, 26, 27, 28, 34) and a terminal end of conveyance; and the second conveyor (32) has a beginning end of conveyance spatially crossing the terminal end of conveyance of the first conveyor (31) and a terminal end of conveyance located on a rear side of the bed (21). A dry-cutting type horizontal hobbing machine according to claim 2, characterized in that the conveyor (31, 32) is formed so wide as to cover the dry-cutting section (22, 23, 25, 26, 27, 28, 34).

Inventors: EGAWA TSUNEO, KOMINAMI TOSHIKAZU, NAKAMURA YOZO, TONOHARA YOSHIHARU, EGAWA, TSUNEO, KOMINAMI, TOSHIKAZU, NAKAMURA, YOZO, TONOHARA, YOSHIHARU, Egawa, Tsuneo, Mitsubishi Heavy Ind., Ltd., Kominami, Toshikazu, Mitsubishi Heavy Ind., Ltd., Nakamura, Yozo, Mitsubishi Heavy Ind., Ltd., Tonohara, Yoshiharu, Mitsubishi Heavy Ind., Ltd.
Applicants: MITSUBISHI HEAVY IND LTD, MITSUBISHI HEAVY INDUSTRIES, LTD.
Application year: 1998
Main classification: B23F23
IPC codes: B23F23, B23Q11