Divisible gearbox in a lathe

Abstract: The divisible gearbox (1) of the work-piece headstock for a lathe or a milling machine comprises the housing (18,19) and a set of gear shafts (2,3,4,5), and has two separable parts including the casing, a first fixed part (18) of the work-piece headstock which incorporates at least the shaft (2) of the headstock spindle (8), and a second separable part (19) which incorporates at least the drive shaft (4) and which slides as a whole out of the machine along support-guide means (23, 24), and which has means (25, 26) to pivot the separable housing (19) to provide free access to the gear shafts (4,5).

Description: The present invention relates to a lathe or milling machine gearbox with a train of several successive shafts of gear wheels, part of which can be separated for removal from the machine. PRIOR ART Known vertical lathes or milling machines with the work-piece headstock fixed to the machine bed have the gearbox gear train housed inside the front of the machine frame from which the headstock casing protrudes, fitted with a removable front cover for access to the interior of the headstock for repairs. The gear train in such known lathes comprises several gear shafts, including the shaft of the headstock working-spindle situated in the first position in relation to the front of the machine, and a shaft for change of speed, all of which are vertical and meshed in succession from front to back, under the frame. In case of repair or replacement of some element of the gearbox, the front of the machine frame is released and removed in order to take out the gear train with a hoist, for repair outside the machine. It is unlikely that a hoist will be available on the lathe site for the removal upward of the gear train and this is, furthermore, a costly task since the entire machine frame has to be dismantled. EP-517387 describes an adaptor for a rotating tool holder with part of the casing containing a transmission gear which can be separated from the headstock. DISCLOSURE OF THE INVENTION The object of the invention is a gearbox which can be divided in two for lathes and milling machines, as defined in claim 1, including the gear train and the gearbox casing, one of the parts of which can be separated and removed for repairs to the gearbox. The shaft of the headstock spindle has a gear wheel coupled with a second transmission shaft and, for repairs, both shafts remain immobile inside the front half of the casing, of the headstock, since access to its components is easy through a front headstock cover. On the other hand, the drive shaft and gearbox shaft are located behind the headstock under the machine frame and it is not possible to access them without removing them. For repairs to or maintenance of the gearbox, to overcome the problem of access to the gear train, part of the casing can be separated from the part of the headstock casing and can be manually removed from the machine. The separable half of the gearbox incorporates devices for sliding it out of the machine with the aid of support elements on the machine bed, and the means to pivot it subsequently in order to provide a view of free access to the interior. DESCRIPTION OF THE DRAWINGS FIGURE 1 is a transverse cross-section view of the gear box according to the invention. FIGURE 2 is a side elevation view of the lathe, with the gearbox in figure 1. FIGURE 3 is a side elevation view of the lathe in figure 2, showing part of the gearbox separated and taken out of the machine. DETAILED DESCRIPTION OF THE INVENTION The gearbox 1 shown in figure 1 is an embodiment of the invention, it has four shafts 2,3,4,5 of respective gear wheels 6,12,15,16 to transmit the rotation movement to the shaft of the headstock spindle 8 which is fixed to the vertical lathe shown in figures 2 and 3, and the chuck, not shown, is located at the top of the work-piece headstock, with the cylinder 10 to drive the grips at the bottom of the spindle 8. The first gear shaft 2 of the spindle is located inside the work-piece headstock on the front of the lathe and has a wheel 6 coupled which meshes with the second transmission shaft 3. The other shafts 3,4,5 of the gear train are located successively one after the other to the back of the lathe and, of these, the second shaft 3 is a transmission shaft with a pinion 12 to drive the shaft 2 of the spindle, while the third shaft 4, with two drive pinions 15, 16 for the transmission of different speeds, is the drive shaft moved by a pulley 13 and belt set, and the fourth shaft 5 belongs to a hydraulic cylinder 5' that drives a device 17 which makes the drive pinions 15, 16 slide to change gear. The shaft 2 of the spindle and the transmission shaft 3 are housed inside the half 18 of the casing of the gearbox 1 while the drive shaft 4 and shaft 5 of the gearbox are housed inside the rear half 19 of said gearbox. The two halves 18 and 19 of the gearbox 1 casing are coupled and joined by a set of bolts 21, the half casing 18 housing the headstock is fixed to the front 20 a of the lathe bed 20 and has a front cover 22 whose entrance provides access to gears 6 and 12 of the spindle and transmission shafts, while half-casing 19 of the two rear shafts 4 and 5 can be removed by releasing the bolts 21, being supported on two pairs of bearings 23 by means of which it slides toward the rear of the lathe along two slide guide-bars 24 supported on the bed 20. Once the casing 19 has been removed from the lathe, it is rotated one quarter turn on a pivot 25 linked to the rear bearings 23 by means of the pivoting arm 26, to reveal the gears 15, 16 of the drive shaft 4 and the gearbox shaft 5, for repair.

Claims: A divisible gearbox for work-piece headstocks on a vertical lathe or milling machine, comprising a set of gear shafts (2,3,4,5) in succession which includes at least the shaft (2) of the spindle (8) and a drive shaft (3), which are housed inside a casing (18,19) of the gearbox (1) attached to the machine bed (20), characterised in that the gearbox (1) is dividable in two parts, one part (4,5,13,19) of them removable including the drive shaft (4) and its corresponding casing (19), is able to be separated from the work-piece headstock, and is provided with means (23,24) for sliding and guiding on the housing (19) to be detached from the machine, and with means (25, 26) for pivoting to allow free access to all the gear shafts (2,3,4,5). The divisible gearbox of claim 1, wherein the means (23,24) for sliding said separable casing and gear shaft part (4,5,13,19) are a pair of support bars (24) fitted with bearings (23), and the means (25,26) for pivoting the removable casing (19) are a pair of pivoting arms (26) secured to the casing (19) and a pivot (25) coupled to the bearings (23).

Inventors: VICARIO BURGOS ANGEL, VICARIO BURGOS, ANGEL
Applicants: DANOBAT, DANOBAT, S. COOP.
Application year: 1998
Main classification: B23Q5
IPC codes: B23Q5