FR3068752A1 - MULTI-STAGE PRECISION TELESCOPIC SCREW - Google Patents

Abstract

The invention relates to a multi-stage telescopic screw device capable of very precise deployment movements in the micrometer range. It consists of a screw and at least one guide which has a guiding role and keeps the system in the axis. The screw and the guide consist of at least three identical stages. But those of the guide, they are not threaded. These stages are organized as follows: the first stage is a shaft comprising, on its lower part, a threaded shoulder; - The last stage is a shaft threaded from the bottom over almost the entire height of the stage and reamed on the rest of its height to leave a shoulder diameter adjusted to the shaft of the screw it contains; the intermediate stage is a bored shaft externally identical to the first stage and internally identical to the last. Whatever the floor, the pitch of the threads are identical. The guide is fixed at its ends and the screw is fixed at one of its two ends, while the other is placed on a bearing and is actuated by a motor by means of pulleys or gears. Since the system does not use fluids, it is not sensitive to weather conditions.

Description

The present invention relates to a multi-stage precision telescopic screw device capable of deployment movements on the order of a micrometer.

Traditional telescopic processes allow deployment movements of the order of a millimeter. In addition, they are very sensitive to temperature of use and bad weather. They are therefore not precise enough for certain applications, such as for example in an additive manufacturing machine.

The device according to the invention overcomes this drawback. It consists of a steel screw that activates the system, and, at a minimum, a steel or aluminum guide that keeps the system in line.

The screw has at least three parts, called stages, which are concentric: a first stage, an intermediate stage and a last stage.

The first stage is a tree comprising, on its lower part, a threaded shoulder.

The last stage is a threaded shaft from below over almost the entire height of the stage, and bored over the rest of its height, in order to leave a shoulder of diameter adjusted to the shaft of the screw it contains .

The middle story is a bored tree. It is externally identical on the first floor, and internally identical on the last.

Whatever the stage, the thread pitches are identical.

In order to implant the screw, two configurations are possible:

- the first floor is fixed; the last stage is placed on a fixed bearing, and a pulley located on the last stage connects the screw to a motor which drives it with a belt;

- the top floor is fixed; the first stage is placed on a fixed bearing and a pulley located on the first stage connects the screw to a motor which drives it with a belt.

These three parts are screwed into each other, so that when either the last or the first stage is set in motion, the first stage and the intermediate stage go up or down according to the direction of rotation.

The movement of the first floor or the middle floor is limited:

- above by the presence of an internal shoulder in the part in which it is screwed;

- below by an external circlip, placed on the top of the floor (in a groove), which abuts on the floor below.

The guide also consists of at least three floors: a first floor, an intermediate floor and a top floor.

They are identical in all respects to the stages of the screw, but do not include threading or tapping.

The first and last floors are fixed. The three parts fit into each other concentrically.

The movement of the first floor or the middle floor is limited:

- at the top by the presence of an internal shoulder in the part in which it moves;

- below by an external circlip, placed on the top of the floor (in a groove), which abuts on the floor below.

Thus, seen from the outside, no thread is visible. The system cannot therefore be blocked by an external body which would get stuck on the threads.

According to particular embodiments:

- other intermediate stages for the screw or for the guide may exist in order to improve the deployment height;

- other guides can be added to improve guidance;

- The pulley / belt assembly can be replaced by another drive means, such as gears, which has the effect of improving the precision of the movement thanks to the reduction in gear;

- the motor used can be a stepping motor;

- other materials can be used.

The attached drawings illustrate the invention: The figure 1 represented in chopped off a first floor of screws with in red its threads • The figure 2 represented in chopped off a middle floor of live with in red its threads • The figure 3 represented in chopped off a latest floor of screws with in red its threads • The figure 4 represented in chopped off a first floor guide. The figure 5 represented in chopped off a middle floor of guide. The figure 6 represented in chopped off a latest floor guide. The figure 7 represented in chopped off a screw and his folded guide

with the threads in red and the pulley in blue.

Figure 8 shows in section a screw and its guide deployed with red threads and blue pulley.

With reference to these drawings, the device presented in FIGS. 7 and 8 represents a screw and its guide at different stages of deployment. They both consist of a first stage: that of the screw is threaded (1) and that of the guide is not (2); and a last stage: that of the screw is tapped (3) and that of the guide is not (4). The screw and its guide are also composed of three intermediate stages threaded and tapped for the screw (5) and non-threaded and non-tapped for those of the guide (6).

The floors fit into each other concentrically. The shoulders (7) have a stop function because they prevent the screws they contain from going higher; but they also have a guiding function because their diameter is adjusted to the diameters of the shaft of the screw they contain.

The circlips placed in the grooves (8) have a stop function by preventing the screws they contain from going lower than the level at which they are located, and thus causing another stage. The upper parts of the first stages (9) are fixed to a plate and thus made integral.

The last stage of the guide (10). The last stage of ment (11).

A pulley (12) is put in is fixed to the ground by a shoulder the screw is deposited on a roller with intermediate movement.

on the last stage of the screw the last stage and the stages this pulley is connected to a

For this, stepper motor by means of a belt. The stepping motor is fixed to the ground, and thus made integral with the last stage of the guide.

This system is here intended to serve as the Z axis for an additive manufacturing machine.

However, the present invention is in no way limited to the embodiments described and shown, but a person skilled in the art will be able to make any variant conforming to his spirit.

Claims (8)

1) Precision telescopic mechanical deployment device characterized in that it comprises a telescopic screw system which has at least three parts called stages: a first stage, an intermediate stage and a last stage: - the first stage is a tree comprising, on its lower part, a threaded shoulder (Fig.l); - the last stage is a threaded shaft from below over almost the entire height of the stage and reamed over the rest of its height in order to leave a shoulder of diameter adjusted to the shaft of the screw it contains ( fig.3); - the intermediate stage is a bored shaft externally identical to the first stage and internally identical to the last (Fig. 2). 2) Device according to claim 1 characterized in that whatever the floor (Fig.l, Fig.2 and Fig.3), the thread pitches are identical. 3) Device according to claim 1 characterized in that the first stage (Fig.l) is fixed while the last stage (Fig.3) is placed on a bearing (ll-Fig.7 and ll-Fig.8) and that the last stage is driven by a motor thanks to a pulley (12-Fig. 7 and 12-Fig. 8) / belt system. 4) Device according to claim 1 characterized in that the first stage (Fig.l) is fixed while the last stage (Fig.3) is placed on a bearing (ll-Fig.7 and ll-Fig.8) and that the top stage is driven by a motor through a gear system. 5) Device according to claim 1 characterized in that the last stage (Fig. 3) is fixed while the first stage (Fig.l) is placed on a bearing (ll-Fig.7 and ll-Fig.8) and that the first stage is driven by a motor using a pulley (12-Fig. 7 and 12-Fig. 8) / belt system or a gear system. 6) Device according to claim 1 characterized in that it is accompanied by at least one telescopic guide consisting of at least three stages which fit into each other concentrically: a first stage (Fig.4) , an intermediate stage (Fig.5) and a last stage (Fig.6) which are identical in all respects to the stages of the screw (Fig.l, Fig.2 and Fig.3), but do not have threads or tapping; its two ends are fixed. 7) Device according to claims 3 and 6 characterized in that the upper part of the first stage of the screw (Fig. 1) and that the upper part of the first stage of the guide (Fig. 4) are fixed to a plate and thus rendered solidarity. 8) Device according to claim 1 characterized in that the inner shoulder of each stage of the screw or guide is adjusted to the diameter of the shaft of the screw or the guide it contains (7-Fig.7 and 7 -Fig.8).