US2156596A - Means for driving the shafts of machine tools at different speeds - Google Patents

Description

May 1939- A. H. LLOYD 2,156,596

MEANS FOR DRIVING THE SHAFTS OF MACHINE TOOLS AT DIFFERENT SPEEDS Filed Nov. 18, 1936 3 Sheets-Sheet l 45 fift l manna..- ,H- f r, 43 j I 54 44 53 33 60 55 56 I fnuenlzr j c/ZZZZZqyd J 9L I May 2, 1939. A. H. LLOYD 2,156,596

MEANS FOR DRIVING THE SHAFTS OF MACHINE TOOLS AT DIFFERENT SPEEDS Filed Nov. 18, 1936 I s Sheets-Sheet 2 y 1939- I A. H. LLOYD 2,156,596

MEANS FOR DRIVING THE SHAFTS OF MACHINE TOOLS AT DIFFERENT SPEEDS Filed Nov. 18, 1936 3 Sheets-Sheet 3 TI I Z9 M QL Patented May 2, 1939 UNITED STATES MEANS FOR DRIVING THE SHAFTS OF MA- CHINE TOOLS AT DIFFERENT SPEEDS Arthur Harold Lloyd, Coventry, England, assignor to Alfred Herbert Limited, Coventry, England Application November 18, 1936, Serial No. 111,542 In Great Britain December 4, 1935 6 Claims. (Cl. 74-459) This invention relates to means for driving the main or feed spindles or other shafts of lathes, drilling machines or other machine-tools at different speeds, the means including a preselective change-speed gearing, i. e., gearing of the kind which can be set by means of a selector control for a selected speed"-whi1e another speed is in being, and subsequently operated by a main control to introduce the selected speed.

The main object of the invention is to provide in a very inexpensive and satisfactory manner for a number of different speeds" all of which can be preselected.

The invention broadly consists in the use of a variable speed driving motor and in connections therewith such that the speed of the motor is varied for a certain combination or combinations by means of the selector and main controls, the full range of speeds being obtained partly by the gearing and partly by the motor.

In carrying out the invention a very satisfactory form of preselective gearing is that described in British Patent Specification No. 382,784. In this prior specification eight different speeds can be obtained by means of three double-acting clutches. In adapting such a gearing, according to the invention, only two double-acting clutches need be used in conjunction with a two-speed electric motor to give altogether eight difierent speeds, or only a single double-acting clutch in conjunction with a four-speed motor.

In British Patent Specification No. 429,741 different speeds are obtained by the sliding of gears into and out of mesh instead of by the use of friction clutches, a friction clutch and brake being interconnected with the movable element of the gearing so that the former will be released and the latter applied while meshing of a gear pair is being effected. In adapting this form of gearing according to the invention, one less double sliding gear may be used, the drive to the gearing being from a two-speed electric motor, or two of the double sliding gears may be left out, the drive in that case being from a four-speed electric motor-when eight speeds" are desired.

British Patent Specification No. 441,141 de scribes a modified form of gearing which includes at least one gear pair associated with an automatic one-way driving device. In this specifica tion, with two double-acting clutches six forward speeds can be obtained in certain conditions, and by the use of a two-speed driving motor the number of speeds obtainable could be increased to twelve, or by the use of one double-acting gears l6, I8 are taking the drive.

clutch and a two-speed motor six different forward speeds" can be obtained.

. Moreover, the gearing of this prior Specification No. 441,141 also embodies a further control by which reverse or forward drives at different speeds can be obtained substantially instantaneously. According to the present invention, reverse or forward drives may be introduced at will by means of the selector and main controls through which the motor speeds and gearing speeds are altered.

In all cases the variable-speed motor is preferably an electric one. If adapted for A. C. operation it may be provided in a known manner with a pole-changing device. If adapted for D. C. it may be resistance, controlled.

In the accompanying drawings:

Figure 1 is afront outline elevation of one form of lathe adapted according to the invention;

Figure 2 is a developed view of the headstock gearing thereof to a larger scale;

Figure 3 is a part-sectional end elevation, also to the larger scale, through the gearing and control means therefor, taken from theleft of Figure 1;

Figure 4 is a plan view of the headstock with the cover removed and the gearing omitted, this view showing more clearly the control mechanism;

Figure 5 is a rear elevational view of the headstock; and I Figures 6 to 14, inclusive, are developed views of the two profile devices of Figures 3 and 4.

In the drawings I I represents a two-speed electric motor having a pulley l2 in driving connection with the driving pulley l3 of the headstock by a belt disposed within the casing It. Fast on the headstock pulley shaft 15 are two differentsized gears l6, I! in mesh, respectively, with gears l8, [9 free upon the layshaft 20. 2| represents a double-acting clutching device of known form by which either of these free gears can be locked to the shaft 20 while the other is released, the clutching device including a slidable actuating'collar 22. In Figure 2 this is shown as having been moved to the left, in which position the The collar can be slid to the right or left by means of the striking fork 23 (Figure 3) formed with an actuating stem 24'. Fast on the shaft 20 (Figure 2) are two different- sized gears 25, 26 in mesh, respectively, with gearsZ'l, 28 free on the shaft 29. Associated with these latter gears isa doubleto acting clutching device 30 similar to that marked 21. The slidable actuating collar 3| thereof is shown in Figure 2 in the left-hand position, in which event the gear- pair 25, 21 is transmitting the drive. The collar can be slid to the right or the left by means of the striking fork 32 (Figure 3) fast with the actuating stem 33. From the shaft 29 the drive can be taken through a gearpair 34 to the spindle 35.

It will be observed that the change-speed gearing described provides for driving the spindle 35 at four different speeds for a given speed of the headstock pulley shaft l5; and as the latter can be driven at either of the two different speeds by the electric motor H, the total number of spindle speeds obtainable is eight. Whereas both the motor speeds could be in the same direction, or one alternatively could be a forward speed and one a reverse, it is here assumed that they are both in the same direction: but the motor can be operated in either direction by means of an independent reversing switch of known form contained within the casing 36 (Figure 5) and operable by the two-way handle 31 disposed at the top of the headstock Also within the casing 36 is the switch through which the two different speeds of the motor can be introduced in a well understood manner, the switch being actuated by the rotation of the rod 38 which extends into the interior of the headstock, as shown in Figures 3, 4 and5. The rod 38 carries-a crank arm 39 engaged at 40 with a slidable collar 4| which is fast with the actuating stem 42.

The actuating stem 42 for the switch and the actuating stems 24, 33 for the clutch devices are grouped together as shown by Figures 3 and 6. In the latter figure the stems are shown by the shaded lines in the position they occupy in the other figures, and the chain lines indicate the alternative positions which they may take up.

For actuating them use is made of two profile devices 43, 43 having complementary recesses on their adjacent faces, as shown in Figure 6. These profile devices are slidably keyed at 44 (Figure 3) on the shaft 45 which is connected by the pair of one-to-one bevel gears 46 (Figure 4) with the shaft 41 connected in turn through a one-to-one gear-pair 48 with a rotatable selector control 49. The latter can be turned into eight different control positions to bring markings on its bevelled surface 50 into alignment with the arrow 5| according to what speed ratio is required. The corresponding eight different positions of the profile devices 43 relatively to the three actuating stems 24, 33, 42 are indicated by the chain lines A to H in Figure 6.

The profile devices can be moved axially towards and away from one another. In Figures 4 and 6 they are shown away from one another, but if they were now brought towards one another and then again separated the actuating stems 24, 33, 42 would be left in the positions indicated by the hatched lines indicated in Figure 6. It will be evident, however, that in other angular positions of the profile devices a diflerent combination of positions for the actuating stems will be obtained. The slow and fast positions of each of the clutch actuating stems. 24, 33 are marked in Figure 6 and also theslow and fast positions of the motor switch actuating stem 42.

For moving the profile devices 43 axially they are formed with grooved collars 52 (Figure 4) engaged, respectively, by the arms of a pair of similar bellcranks 53 having at 54 slotted connections with an axially slidable rod 55. This carries a roller 56 in engagement with a cam 51 on the main control shaft 58, such that movement of the main control in the appropriate direction will effect axial movement of the rod 55 (to the right in Figure 3 and downwardly in Figure 4) in the direction necessary to move the profile devices towards one another, thus to reposition the actuating stems 24, 33, 42 according to the setting of the selector control 49. Movement of the maincontrol 58 in the other direction allows the rod 55 to return under the bias of the spring 59, such bias being adjustable by means of the nut 60 on the rod.

It will be observed that with the parts in the positions indicated the selector control 49 can at any time be rotated to one of the other sevenJ operative positions according to what fresh spindle speed is desired, and that subsequently when this fresh speed is to be introduced it is only necessary to actuate the main control 58. The complete speed range is thus provided partly by the electric motor and partly by the gearing.

Referring to Figs. 6 to 14 inclusive, the actuating stems in their neutral positions will be disposed centrally of the dot and dash line of each figure. Assuming that next to the lowest speed is desired, the profile devices 43 are rotated by means of the operator 49 to the positions here shown, so that when the shaft 58 is operated to move the profile devices towards each other, as shown in Fig. '7, the actuating stems 24 and 33 will be shifted to the left of the neutral position, and the motor speed stem 42 will be shifted to. the right. At this time the motor is operating at its highest speed, and the drive is through gears 34, 21, 25, I8, and IS. The stem actuators 43 may be released from the ,stems at any time desired as the stems 24, 33, and 42 will remain in their selected positions.

In Fig. 8, the stems 24 and 33 are shown shifted to the right, and the motor stem or operator 42 to the left, giving low speed for the motor. The spindle speed in this instance is obtained through gears 34, 28, 26, I9, and 11. In Fig. 9 the stems 24 and 33 are shown in the same position as Fig. 8, but here the motor operator is shifted to high speed.

In Fig. 10, the motor operator 42 is shifted to low speed, which is to the left of the neutral position, and the gear selector stems 24 and 33 are shifted in opposite directions. In the positions shown in Fig. 10, the speed is obtained through gears 34, 28, 26, I8, and 16.

In Fig. 11, the gear selector stems 24 and 33 are in the same positions shown in Fig. 10, with the same gear train in operation, but here the motor speed is in high, the motor operator 42 being shifted to the right, which is high speed.

In Fig. 12, the motor operator 42 is shifted to the left, or low speed, and the gear selectors 24 and 33 are in positions opposite to the positions shown in Figs. 10 and 11. Here the spindle speed is obtained through the gear train 34, 21, 25, I9, I 1, with the motor at low speed.

Figure 13 shows a gear selection similar to Fig. 12, but the motor operator 42 is here shifted to high speed.

In Figure 14 there is shown the extreme low speed, with the motor operating at low speed, and the gear train the same as that for Fig. 6. Here the gear train is through the gears 34, 21, 25, I8 and I6.

While one particular form of lathe driving means, comprising a two-speed electric motor and a four-speed constant-mesh gear-box, has been specifically described, it will be evident that other combinations can be used without departing from the spirit of the presentinvention. By using 6 a variable-speed motor in conjunction with preselective gearing and connecting the former to be operated by the selector and main controls of ,the gearing, a very wide range of'speed ratios is open to the designer.

What I claim as my invention and desire to secure by Letters Patent of the United States is: 1. In a machine-tool, a preselective change speed mechanism having selector and main controls, a variable-speed motor, actuating stems through the movements of which the speeds of said gearing and motor can be altered, and a pair of profile devices co-acting with said actuating stems, said profile devices being movable by the rotation of said selector control for set- 20 ting purposes and being subsequently movable by said main control to operate said actuating stems for the gearing and motor to introduce a difierent motor or gearing speed, or both, according to the setting of said selector control.

2. In a machine-tool, a preselective changespeed mechanism having selector and main controls, a variable-speed motor, actuating stems through the movements of which the "speeds of said gearing and motor can be altered. and a 30 pair oi rotatable, axially-movable profile devices coacting with said actuating stems, said profile devices being rotatable by the rotation of said selector control for setting purposes and being subsequently axially movable by said main con- 35 trol to operate said actuating stems for the gearing and motor to introduce a different motor or gearing speed", or both, according to the setting of said selector control.

3. In a machine tool, a change-speed mechu anism, a variable-speed motor, movable actuating stems connected to alter the speed of said mechanism and motor, movable profile devices coacting with said stems, a preselector connected to move said devices without movement 0! the stems to a potential position for speed change, and a main control also connected to said devices for instantaneously moving said devices from said potential position into moving engagement with said stems whereby to accomplish speed changing.

4. In a machine tool, a change-speed mechanism, a variable-speed motor, movable actuating stems connected to alter the speed of said mechanism and motor, rotatable and axially-shiftable profile devices coacting with said stems, a preselector connected torrotate said devices without disturbing said stems or the speed in being to a new potential position for speed change, and

'a main control connected to instantaneously shift said devices from said potential position into moving engagement with said stems whereby to accomplish speed changing.

5. In a machine tool, a change-speed mechanism, a variable-speed motor, movable actuating members connected to alter the speed of said mechanism and motor, movable profile devices coacting with said members, a preselector connected to move said devices when out of moving relation to said members to a new potential position for speed change, and a main control connected to move said members from said potential position in moving relation to said members whereby to accomplish instantaneous speed changing in accordance with the preselection.

6. In a speed changing mechanism, including a pair of parallel shafts, intermeshing gears on said shafts, a pair of confronting clutch elements rotatable on each shaft, a clutch member spiined on each shaft between said confronting clutch elements, a shifting stem for each clutch member, a motor speed changing stem, a pair of stem actuating members provided with confronting notches and projections for engagement with said stems, and operating means for said stem actuating members.

ARTHUR H. LLOYD.

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