Title:
Mathematical drawing instrument
United States Patent 2487345


Abstract:
The orientable heads for drawing instruments which are known at the present time generally comprise a ring which is connected to the movable arms of the instrument and on which is rotatably mounted a support on which are fixed the drawing instruments and which the draughtsman can move into...



Inventors:
Sosthene, Liber Henri
Application Number:
US70711046A
Publication Date:
11/08/1949
Filing Date:
11/01/1946
Assignee:
ILE D ETUDES & INV S LIBER SOC
Primary Class:
International Classes:
B26B19/14; B43L13/08
View Patent Images:
US Patent References:
2394344Drafting machine1946-02-05



Foreign References:
DE575169C1933-04-25
Description:

The orientable heads for drawing instruments which are known at the present time generally comprise a ring which is connected to the movable arms of the instrument and on which is rotatably mounted a support on which are fixed the drawing instruments and which the draughtsman can move into any desired angular position by means of a central operating knob.

An automatically acting bolt enables the support to be locked in predetermined positions, for example every ten or fifteen degrees; said bolt is moved into the retracted position by a first lever which, when released, allows the bolt to engage automatically as soon as the support, as it rotates, comes opposite one of the said predetermined positions. It is however advantageous to be able to neutralise completely said bolt and prevent it from engaging automatically so as to enable said support to rotate quite freely. This neutralisation is obtained by means of a second lever which locks the first. Finally, it should be possible when the bolt is neutralised, to be able to lock the support in any desired position; this locking is obtained by means of a shoe which acts by braking on the periphery of the ring and which is operated by a third lever.

It will be readily understood that the manipulation of such heads is comparatively delicate and inconvenient and that the draughtsman requires both his hands to effect it since in certain cases, he is obliged not only to rotate the support, but also to operate successively the three aforesaid levers, which are not very close to one another, or to the central control knob of the support.

The present invention enables an orientable head to be obtained which has the same prqperties as the present known heads, but the operation of which is much more convenient and can easily be effected with one hand.

The head according to the invention is essentially characterised by the fact that it comprises, for effecting the various above-mentioned operations, a single control member which is located in the immediate vicinity of the central control knob of the support and the operation of which in one direction produces: in a first phase, the disengagement of the bolt, with the possibility, however, for said bolt to return to its engaged position if the action stops on this member before it has gone beyond said first phase of movement; in a second phase, the neutralisation of said bolt which can then no longer engage; and finally, in a third and last phase, the locking of the support by means of the braking shoe, the bolt remaining neutralised, while the operation of this single control member in the opposite direction produces the reverse operations.

The draughtsman can then very easily, using only one hand, act on the central knob in order to orient the head and on the aforesaid member in order to effect the various locking and unlocking operations hereinbefore mentioned.

Other advantages and peculiarities of the present invention will become apparent from the ensuing description thereof made with reference to the accompanying drawings which show, diagrammatically and merely by way of example, an embodiment of the head according to the invention.

In said drawings: Fig. 1 is a view in sectional elevation of said head.

Fig. 2 is the corresponding plan view, the case of the mechanism being assumed to have been removed.

Figs. 3, 4 and 5 show respectively an elevational view, a top plan view and a bottom plan view of one of the main parts of the mechanism.

Fig. 6 is a diagram representing the development over 3600 of the two sets of cams of the mechanism.

Figs. 7 and 8 show a plan view which is very diagrammatic, of the retracting pawl in two different positions.

Fig. 9 shows an improvement.

Fig. 10 is a view of another embodiment of said head, in longitudinal section.

Fig. 11 is the corresponding plan view, the case of the mechanism being assumed to have been removed.

Fig. 12 is a perspective view of said mechanism.

Fig. 13 is a plan view on a smaller scale of the case forming a handle.

Fig. 14 is a plan view showing a modification of a detail of construction.

The head according to the invention comprises a ring I which is fixed on the movable arms (not shown) of the drawing instrument, by means for example of pins passing through holes 2 provided in said ring.

On said ring is rotatably mounted, by means for example of a central pivot 3, a support 4 on extensions 5 of which can be fixed the drawing instruments (not shown). On said support 4 is fixed a case 6, the upper part of which forms an operating knob 7 enabling the support 4 to be rotated relatively to the ring.

On the case 6 is rotatably mounted a second knob 8 which is located in the immediate vicinity of the knob 7 and which drives, as it rotates, by means of claws 9 engaging in notches 10, a sleeve II shown in Figs. 3 to 5. Said sleeve can rotate on a fixed tube 12 secured to the support 4 through the intermediary of the support 36, and inside which can slide longitudinally a bolt 13, the lower end of which can project below the support 36 and engage in one or the other of the perforations such as 14 provided for example every fifteen degrees in the ring I.

Said bolt has passing through it two pins 15 and 16, the ends of which pass through buttonhole slots 17 of the pivot-tube 12 and project on either side of said tube (Fig. 2).

The upper pin 15 co-operates with the upper face of the sleeve 1 which forms two diametrically opposite cams, the cross-sectional shape of which is developed in Fig. 6. Eath of said' cams co-operates with one of the ends of the pin 15 and comprises a flat sunken in portion 1818a, a slope 19-19a, and finally a raised flat portion 20-20a. The lower pin 16 co-operates in the same manner with the lower face of the sleeve forming identical cams 21-22-23, 21rl-22a23a (see Figs. 3, 5 and 6).

Said sleeve I I is on the other hand provided with a segment-shaped skirt 24 on the edge 25 of which acts the end of a pawl 26 which can rotate about the central pivot 3 and is subjected to the action of a retracting spring 27. Said pawl thus retracts the sleeve 1 (and consequently the knob 8) into its normal, position shown in Fig. 7 in which only the pawl 26 and the skirt 24 have been shown.

For this position, the pin 16 is held in its.low position by the flat faces 2 1-2 a of the lower cam of the sleeve (Fig. 6). The bolt 13 is therefore held in its low position in which it is engaged in one of the perforations 14 and locks the support 4 in the corresponding position.

If the knob 8 is slightly rotated and consequently the sleeve II, the slopes 1S-1 9a of the upper cam cause the bolt 13 to move upwards and become disengaged from the perforation 14 so that the draughtsman can rotate the support relatively to the ring. However, if the angle through which the sleeve 11 has rotated is less than that over which the slope extends and which is equal to the angle through which the sleeve has to rotate in order that the skirt 24 shall escape the action of the retracting pawl 26 (compare Figs. 7 and 8), the bolt 13 will automatically engage in the first perforation 14 encountered during the rotation of the support, -as soon as the draughtsman stops his action on the knob 8.

In fact, at this instant, the pawl 26 returns the sleeve to its inoperative position and the slopes 22-22a of the lower cam positively control the downward movement of the pin 16.

On the other hand, if the draughtsman rotates the knob 8 further, the pin 15 reaches the raised flat portions 20-2 a of the.upper cam. Simultaneously the skirt 24 escapes the action of the pawl 28 (see Fig. 8). The bolt 13 is.then neutralised, i..e. it is.locked.in its high position and can no longer engage in a perforation 14, even if all action on the knob 8 is stopped. The support 4 is completely free relatively to the ring.

Means. are then provided to enable it to be locked in any desired position, this being effected by rotating the knob 8 still further and still in the same direction. In the example shown, this result is obtained by means of a- toothed pinion 2Ta meshing with a pinion 28 which is prevented from moving longitudinally and in an axial tapping of which is screwed a threaded rod-29 which is prevented from rotating and which carries at one of its lower ends a shoe 30 the heel 31 of which is adapted to act against the lower peripheral face of the ring i, During the two first phases of the rotary movement of the knob 8, the rotation of the. pinion 28 has simply: had the effect of moving the shoe 38-31 towards the face of the ring without bringing it into contact with same. But, if the rotary movement of said knob 8 is continued beyond said two first phases, the shoe 30--31 continues to move. upwards and presses against the face of the ring, thereby locking the support 4.

When the knob 8 is operated in the opposite direction starting from this extreme locking position, it begins by releasing the shoe 30-31, thereby releasing completely the support; if the movement is continued, the slopes 22-22a of the lower cam of the sleeve II (Fig. 6) positively control the downward movement of the bolt 13, when it is located opposite a perforation 14.

Thus the draughtsman can very easily, with one hand, act on the central knob 7 in order to rotate the support 4 and act on the adjacent knob 8 in order to control the various locking or unlocking operations hereinbefore mentioned.

It will be observed that it is only by way of example that a particular mechanism for carrying out the invention has been illustrated and *in described; any other equivalent mechanism could be adopted, the essential characteristic resting in the fact that the various operations which it is necessary to be able-to effect on the head are all controlled by a single member located in close , a proximity to the central operating knob.

The head which has just been described is provided, in the usual manner, with a graduation 32, marked on the ring I and with which co-operates a pointer 33 carried by the support 4. Ac;no cording to an advantageous characteristic of the present invention, there is provided as shown in Fig. 9, a segment 34 (made of Celluloid for example) which is fixed to one of the parts I or 4 and which: co-operates with a graduation car:;a ried by the other of said parts. Said segment does not carry any indelible indication, but the draughtsman can mark thereon any indications he pleases. If for example he has to make a drawing of which a part requires the head to be ',, in the zero position, whereas another part requires said head to be displaced 200, he will make a. mark A opposite the zero graduation of the scale 35 of the support 4 and a mark B opposite the 20° graduation. Subsequently, it will only be in necessary for him, according to whether he has to effect such or such a part of the drawing, to bring the zero graduation of the scale 35 opposite the mark A or the mark B.

Ini Pigs. 10 to 14 another embodiment has been r.n shown of the head according to the invention.

According to this embodiment, the knob 8 carries with it; as it rotates, the bolt 13 by means of its claws 9 between which are engaged projections 40 secured to said bolt; said projections are also enas gaged in notches 41 of the sleeve II so that said sleeve is also carried round in the rotary movement of the knob 8. Said sleeve II is provided, on its lower face, with two diametrically opposite cam surfaces 22 and 22a rotatably supported e0 on the fixed tube 12, so that the beginning of the rotary rmovement of said sleeve (from its inoperative position Fia's. 10 and 12), has the effect of lifting same; the bolt 13 is carried along with this longitudinal upward movement by means of the projections 40. Said sleeve I carries, on the other hand, a cam 43 which has a cylindrical portion 43a which is centred, on the geometrical axis of the sleeve 11 and a portion- 43b which extends eccentrically outwards. With said cam co-operates the upper arm 3sa.of a shoe 30 which pivots at 33b on the support 38 and the lower arm 30c of which is capable, of engaging with the lower face of the ring i. The cam 43 terminates by- a radial projection 44 which, in the 76 normal inoperative position, abuts against the arm 30a of the shoe 30 (Fig. 12); the sleeve I1 is retracted into this position by the spring-pressed pawl 26 acting on an edge 25 of said sleeve.

According to another characteristic of this embodiment, the case 6, instead of simply forming a central operating knob 7, is extended at 6a (Fig. 13) and forms a regular handle which the draughtsman can grip firmly. The draughtsman can then very conveniently, with one hand, rotate the knob 6 and operate the head as he pleases.

In a general manner, the mechanism which has just been described operates in the same conditions as that of the embodiments of Figs. 1 to 9, i. e. in the following manner: In the inoperative position (position shown in the drawing), a spring 45 (Fig. 10) holds the bolt 13 and the sleeve 11 in their low position for which the lower end of said bolt is engaged in one of the perforations 14, thereby locking the support 4 in the corresponding position. If the draughtsman rotates slightly the knob 8, the bolt 13 and the sleeve 11 are carried along with this movement; the slopes 42 of the sleeve 11 then cause a slight upward movement of said sleeve and of the bolt, said bolt becomes disengaged from the perforation 14, so that the draughtsman, by acting on the handle 6a, can rotate the support 4 relatively to the ring I. However, if the angle through which the sleeve 11 has rotated is smaller than that through which it has to rotate for its edge 25 to escape the action of the retracting pawl 26, the bolt 13 will engage again automatically in the first perforation 14 encountered during the rotation of the support, if the draughtsman has stopped acting on the knob 8. In fact, at this instant, the pawl 26 returns the sleeve to its inoperative position.

On the otner hand, if the draughtsman rotates the knob 8 further, the edge 25 escapes the action of the pawl 26. The bolt 13 is thus neutralised, i. e. it is locked in its high position and can no longer engage in a perforation 14, even if all action on the knob 8 stops. The support 4 is completely free relatively to the ring 1.

During this angular displacement of the sleeve SI, it is the cylindrical portion 43a of the cam 43 which has moved opposite the shoe 30 which in that case has not received any impulse. On the contrary, if the draughtsman rotates the knob 8 further, the eccentric portion 43b of said cam acts on said shoe 30 and causes it to pivot in a clockwise direction. The lower arm 30c bears against the lower face of the ring 1, thereby locking the support 4.

When the knob 8 is operated in the opposite direction starting from this extreme locking position, it begins by releasing the shoe 30, thereby completely freeing the support; if the movement is continued, the sleeve 1 is finally returned to its inoperative position for which the bolt 13 engages in the first perforation 14 encountered.

In the example shown in Figs. 10 to 14, the ring I is not directly secured to the part 46 which is intended to be fixed on the movable arms (not shown) of the drawing instrument. The position of said ring can, on the contrary, be adjusted to a certain extent relatively to said part 46. This possibility of adjustment is obtained by means of a micrometer screw 47 engaged in a nut 48 carried by the part 46; the micrometer screw 47, when it is operated, produces the movement of a slider 49 secured to the ring I, which can pivot at 50 on the part 46. It will be immediately understood that when the screw 47 is rotated, the ring I is made to pivot relatively to the part 46 and, consequently, the angular adjustment of said ring relatively to said part is obtained. The locking of these two parts is obtained by means of a locking handle 51. In the modification shown in Fig. 14, this same result is obtained by means of a knob 52 rotating on the part 46 and secured to the eccentric 53a which controls the slider 53.

It is moreover obvious that the invention has only been described and illustrated in an explanatory and non-limitative manner and that modifications of detail may be made therein without altering its essence.

I claim: 1. An orientable head for drawing instruments comprising a ring connected to the movable arms of the instrument, a support rotatably mounted on said ring and on which are mounted the drawing instruments, a central knob for operating said support, an automatically engaging bolt for locking the support in predetermined positions, means for neutralising said bolt, a braking shoe for locking the support in any desired position, a single control member located in close proximity to said central knob and provided with a sleeve carrying a first set of cams provided with slopes which produce, at the beginning of the movement of said member in one direction, the upward movement of said bolt, and a second set of cams provided with slopes, which control the downward movement of said bolt at the end of the movement of said member in the opposite direction, the cams of the first set having, after said slopes, a raised flat portion holding said bolt in the position of non-engagement, a pinion secured to said sleeve, a second pinion meshing with the first pinion and prevented from moving longitudinally, an axial tapping provided in said second pinion, a threaded rod screwed in said tapping and prevented from rotating, said rod carrying the braking shoe which is adapted to bear against the periphery of said ring when said control member reaches the end of its travel.

2. Orientable head according to claim 1, characterised by the fact that so long as the operating member has not gone beyond the first phase of its movement (corresponding to the action of the slopes of the first set of cams), it is retracted by a spring-pressed pawl which automatically stops its retracting action when said member continues its movement beyond said first phase.

HENRI SOSTHENE LIBER.

6O 0 REFERENCES CITED The following references are of record in the file of this patent: 05 UNITED STATES PATENTS Number Name Date 2,394,344 Wallace ----------- Feb. 5, 1946 FOREIGN PATENTS Number Country Date 575,169 Germany --------- Apr, 25, 1933