This invention relates to machine tools which have an input drive shaft and at least two parallel output shafts which are arranged to be driven in unison by the input drive shaft.

It is well known to provide such machine tools, particularly drilling machines having one input and multiple output spindles. With such machines it is possible to drill a number of holes, or to perform similar machining operations simultaneously. However it is very difficult, if not impossible, to adjust the position of all of the output spindles while enabling them to be driven in unison from the input drive shaft.

It is an object of the present invention to provide such a machine tool where the position of all the output shafts can be readily adjusted.

According to the present invention a machine tool has an input drive shaft and at least two parallel output shafts arranged to be driven in unison by the input drive shaft; means for displacing one of the output shafts in a direction normal to its length relative to the axis of the input drive shaft and means linking all of the output shafts whereby displacement movement applied to said one output shaft causes simultaneous displacement movement of each other output shaft in a direction normal to its length relative to the axis of the input drive shaft.

The means linking all the output shafts cause the displacement of said one output shaft to be repeated on all of the other output shafts so that they are all displaced simultaneously.

In a preferred arrangement each output shaft

is arranged parallel with a separate idler shaft and the output shaft is pivotable around the idler shaft with gears on the output shaft and the idler shaft remaining in meshing relation.

It is convenient for each output shaft to be linked to its idler shaft by a radius arm which permits pivoting movement of the output shaft relative to the idler shaft.

In order that the invention may be more readily understood it will now be described, by way of example only, with reference to the accompanying drawings, in which:-

Figure 1 is a front elevation of apparatus in accordance with the invention;

Figure 2 is a section on the line BB of Figure 4;

Figure 3 is a section in the line CC of Figure 4; and

Figure 4 is a section side elevation on the line DD of Figure 3.

The figures show a machine tool in the form of a multi-spindle drill but the invention is also applicable to multi-spindle reaming and boreing mills.

The machine tool comprises a generally cylindrical body part mounted for vertical movement on two columns 3 extending upwardly from a base plate 2. The base plate can be of any convenient form for mounting on the worktable of a machine tool (not shown) .

The body part comprises a generally cylindrical cup-shaped housing 1 facing downwardly with its open end closed by a plate 4. The housing 1 includes a pair of lugs which enables the housing to

slide on the columns 3.

An input drive shaft 16 extends vertically through the housing and is mounted in sets of bearings 32, 36 and 52 which allow the drive shaft to be rotated with respect to the housing. The drive end of the drive shaft is above the housing.

Four output shafts 21 extend in parallel relation downwardly from the underside of the housing and they are all spaced equidistant from the axis of the input shaft. The output shafts are such that drill chucks or the like can be removably connected to them.

Inside the housing 1 there are three circular plates 5, 6 and 7 extending in parallel relation normal to the longitudinal axis of the shaft 16. Plates 5 and 6, referred to as the top and middle gear plate respectively, are secured together in spaced apart relation by means of spacers 18. The shaft 16 is rotatably mounted in these plates by means of bearings. Four idler shafts 17 are rotatably mounted in the plates 5 and 6 at symmetrical positions around the axis of the shaft 16. Each idler shaft carries a spur gear 19 on the part of the shaft between the top and middle gear plates. All of the gears are in constant mesh with a similar spur gear 19 mounted on the shaft 16 between the top and middle gear plate. Thus rotation of the input drive shaft is transmitted in the opposite direction to each of the idler shafts. The idler shafts terminate between the plates 6 and 7 and the portion of each idler shaft between those plates carries a further spur gear 20.

The plate 7 in the housing is referred to as the scroll plate because it has four arcuate slots 7A cut in it. The plate is rotatable with respect to the

shaft 16 and rests on the bottom plate 4 of the housing. Plate 4 has four elongate slots 4A formed in it. These slots extend symmetrically of, and radial to, the axis of the shaft 16 which projects through the plate.

The arcuate slots in the plate 7 overlie the elongate slots in the plate 4 and the plates are arranged so that the radial slots intersect the corresponding arcuate slots. The upper ends of the output shafts 21 project through the slots in the plates and each output shaft carries a spur gear 20 at its upper end. The spur gear on each output shaft meshes with the spur gear 20 on the corresponding idler shaft 17.

Each pair of spur gears 20 on an idler shaft and on an output shaft are linked together by upper and lower radius arms 8B and 8T, respectively. The idler shaft and the output shaft penetrate through the radius arms and the arms of each pair are secured together with bolts with spacers 60 between the arms. The arms permit the gear 20 on the output shaft to precess around the gear 20 on the idler shaft to a limited extent while keeping the gears in meshing relation. One of the output shafts, referred to as the control shaft 21C, passes through a hole in a bracket 14 which rests on the plate 7. An upstanding end of the bracket is connected to the spindle of a micrometer device which is secured to the side wall of the housing 1. The longitudinal axis of the micrometer spindle is radial to the axis of the shaft 16 and operation of the micrometer device displaces the spindle and causes the control shaft 21C to be moved sideways normal to the direction of its length. This sideways movement of the

control shaft is permitted because it passes through the radial slot in the plate 4. Movement of the control shaft causes it to bear against the wall of the arcuate slot causing limited angular rotation of the plate 7.

The top of the housing 1 has an upstanding collar which is surrounded by a clamping cam 25. A clamping rod 38 projects from the cam. Four locking pins 24 project through the wall of the housing 1 and are engaged at their top end by the cam 25 and their bottom ends engage the top gear plate 5. When the clamping cam 25 is rotated it rides up the locking pins forces them down into engagement with the plate 5. This load is transmitted down to the plate 7 holding it firmly against plate 4 and preventing angular relative rotation between them. When the clamping cam is rotated in the opposite direction, the pressure is released and the plate 7 can rotate relative to the plate 4.

In use, the clamp is released and the micrometer is operated to accurately position the control output shaft 21C to the desired radial position relative the longitudinal axis of the shaft 16. The upper and lower radius arms permit the spur gear 20 on the shaft to pivot while still remaining in meshing relation with the pinion 20 on the idler gear. The moving control output shaft 21C engages against the wall of the arcuate slot causing the plate 7 to rotate thus moving the intersection points of the arcuate and elongate slots of the other three output shafts. Consequently the other output shafts are displaced sideways in a like manner to the displacement of the control output shaft. Movement of the output shafts

causes appropriate rotation of the spur gear 20 at the ends of the idler shafts and the idler shafts rotate around the spur gear 20 on the input shaft 16 thus rotating the plates 5 and 6 within the casing. When the desired positions of the output shafts have been obtained, the clamped is operated to lock the plates in their angular positions.

Thus, in accordance with the invention, displacement movement applied to the control output shaft causes simultaneous displacement movement of each of the other output shafts relative to the longitudinal axis of the input drive shaft.

Although four output shafts have been shown and described, it will be appreciated that the minimum is two output shafts and, in theory, but not necessarily in practice, a multiplicity of output shafts could be provided.

A drill bit could be mounted on an extension of the output shaft 16 below the housing.

In an alternative embodiment, the output shafts may be arranged in a straight line passing through the axis of the input shaft.