JP6740090B2 - Screw feeder - Google Patents

Description

The present invention relates to a screw feed device in which a nut and a nut holder screwed into the lead screw are moved straight by rotation of the lead screw.

Conventionally, in this type of invention, as described in Patent Document 1, for example, a lead screw rotated by the rotational force of a drive motor, a nut screwed to the lead screw, and a non-rotatably supported nut. There is a nut holder, and the object to be conveyed is conveyed by the nut holder in a straight direction along the screw axis direction (for example, see Patent Documents 1 and 2).

JP-A-8-203007 JP, 2009-255890, A

By the way, in the conventional screw feeding device, as illustrated in Patent Documents 1 and 2, due to the connection structure between the nut holder and the object to be conveyed, the external force acts by being biased toward the radial end of the nut holder. There is a case. In such a case, the center line of the nut may be inclined with respect to the screw axis direction, and the frictional resistance between the nut and the lead screw may be significantly increased.

In order to solve such a problem, the present invention has the following configurations.
A drive-rotating lead screw, a nut screwed to the lead screw, a nut holder that non-rotatably supports the nut and is pressed against the nut by an external force along the screw axis direction, and does not rotate the nut holder. A guide member that guides in a straight direction along the screw axis direction, and one member of the nut and the nut holder has one of the other members on both sides in the radial direction with the lead screw placed on the center side. Is provided with a pair of pressing projections, and the nut holder has an action point for receiving the external force at one end side in the radial direction intersecting the arrangement direction of the pair of pressing projections. Feeder.

It is an exploded perspective view of the screw feed device concerning the present invention. (A) is a perspective view of the screw feed device concerning the present invention, and shows a nut and a case with a two-dot chain line. (B) is a perspective view showing a nut of the screw feeder. It is a longitudinal cross-sectional view of the same screw feeder. It is a principal part expanded longitudinal cross-sectional view of the same screw feeder. It is a perspective view showing an example of a nut holder. (A) is a top view of a nut holder, (b) is sectional drawing which follows the bb line in (a), (c) is sectional drawing which follows the cc line in (a). It is a schematic diagram which shows an example of the drive device provided with the screw feed device which concerns on this invention.

Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same reference numerals in different drawings indicate parts having the same function, and redundant description in each drawing is omitted as appropriate. In the following description, for convenience, the output side in the axial direction of the screw feed device 1 may be referred to as “front” and the opposite side thereof may be referred to as “rear”.

The screw feed device 1 includes a case 20, an annular rear support member 30 fixed to the rear end side of the case 20, a lead screw 40 that is driven and rotated by the rotational force of the rotary drive source 10, and a lead screw 40. The nut 50 screwed together, the nut holder 60 that non-rotatably supports the nut 50 and is pressed against the nut 50 by an external force along the screw axis direction, and the lead screw 40 that is fixed to the front end side of the case 20 and is rotatable. A front support member 70 for supporting and a guide member 81 for guiding the nut holder 60 in a straight direction along the screw axis direction without rotating the nut holder 60, and the rotational force of the rotary drive source 10 connected to the rear end of the case 20. The lead screw 40 is rotated by and the transmission member 90 is pulled.

The rotary drive source 10 in the illustrated example is a DC motor, and includes a rotary shaft 11, a rotor (not shown) fixed to the outer periphery of the rotary shaft 11, and a stator (not shown) provided around the rotor. And a cylindrical motor case 12 in which the stator is fixed to the inner peripheral surface, and a front cover 13 on the front end side of the motor case 12, and the rotary shaft 11 is projected forward (see FIG. 3). ..
On the front end side of the rotating shaft 11, there is provided an engaging portion 11A which is fitted to the rear end portion of the lead screw 40 and transmits a rotational force. According to the illustrated example, this engaging portion 11A has parallel surfaces on both sides in the radial direction, and these parallel surfaces are brought into contact with the inner surface of the groove-shaped engaged portion 41A at the rear end of the lead screw 40. I have to.
The rotary drive source 10 can be replaced with a rotary drive source having a structure other than that shown.

The case 20 integrally has a cylindrical main body portion 21 and an annular connecting portion 22 provided at the rear end of the main body portion 21. The connecting portion 22 loosely inserts the rotary shaft 11 of the rotary drive source 10 toward the center thereof, and is attached to the front cover 13 of the rotary drive source 10 by a fastener 23 (eg, screw or bolt) inserted near the outer periphery. It is fixed and fixed.

The rear support member 30 includes a bearing portion 31 that rotatably supports the rear end side of the lead screw 40, and an annular base portion 32 that is integrally fixed to the outer peripheral side of the bearing portion 31.

The bearing portion 31 is a bearing member that has a flange portion 31A that protrudes radially outward in an annular shape on the front end side. The bearing portion 31 is inserted into the annular base portion 32, and the flange portion 31A is brought into contact with the front end surface of the annular base portion 32 so that The base 32 is supported so that it cannot rotate and cannot move back and forth.

The outer peripheral portion of the annular base portion 32 is fixed to the inner peripheral surface of the main body portion 21 of the case 20 such that it cannot rotate and cannot move back and forth. This fixing means may be, for example, fitting, welding, adhesion, or the like.

The lead screw 40 includes a rear shaft portion 41 fitted to the rotary shaft 11 of the rotary drive source 10, a flange portion 42 connected to a front end side of the rear shaft portion 41, and a front end portion of the annular flange portion 42 extending forward. The feed screw portion 43 provided and a front shaft portion 44 protruding forward from the front end portion of the feed screw portion 43 are coaxially and integrally formed.

The rear shaft portion 41 is formed in a substantially columnar shape, and has a parallel groove-shaped engaged portion 41A which is fitted to the engaging portion 11A at the front end of the rotating shaft 11 on the rear end surface thereof. The rear shaft portion 41 is rotatably supported by being inserted into the bearing portion 31 of the rear support member 30.
The flange 42 is formed in an annular shape having a diameter larger than that of the rear shaft portion 41, and the rear end surface of the flange portion 42 is brought into sliding contact with the front end surface of the bearing portion 31.
The feed screw portion 43 is formed in a long shaft shape and has a trapezoidal screw-shaped male screw portion on the outer peripheral surface thereof. A nut 50, which will be described later, is annularly fitted and screwed at an intermediate position in the longitudinal direction of the feed screw portion 43.
The front shaft portion 44 is formed in a substantially columnar shape, and an outer peripheral surface thereof is rotatably supported by a bearing portion 71 of the front support member 70.

According to the illustrated example, the nut 50 is formed in a substantially rectangular tube shape, and the corner portion of the outer periphery thereof is chamfered into a convex curved surface shape. On the inner peripheral surface of the nut 50, a trapezoidal screw-shaped female screw portion is formed so as to fit with the male screw portion of the lead screw 40.
The nut 50 is non-rotatably and movably fitted back and forth in a nut holder 60, which will be described later. The nut 50 is in contact with a pressing protrusion 62B, which will be described later, in the nut holder 60 and is screwed into the lead screw 40.

The nut holder 60 is formed in a concave shape in cross section having a substantially cylindrical tubular portion 61 and a bottom wall portion 62 at the rear end inside the tubular portion 61 integrally (see FIG. 5 ), and the nut 50 is minute inside. Fitted together with play.

The cylindrical portion 61 has an outer peripheral surface formed in a cylindrical shape along the inner peripheral surface of the case 20, and an inner peripheral surface formed in a substantially rectangular cylindrical shape along the outer peripheral surface of the nut 50.
On the outer peripheral surface of the tubular portion 61, guide grooves 61A penetrating in the front-rear direction are provided on both sides in the radial direction. These guide grooves 61A and 61A are arranged at both ends of the pair of pressing protrusions 62B and 62B, which will be described later, in the arrangement direction (see FIG. 5). Then, each guide groove 61A is fitted into the guide member 81 and is in sliding contact therewith.

Further, on the peripheral wall of the tubular portion 61, locking holes 61B penetrating in the front-rear direction are provided on both sides in the radial direction substantially orthogonal to the direction in which the pair of pressing protrusions 62B, 62B are arranged (FIGS. 5 and 6). reference).
The locking hole 61B is formed in the shape of a stepped hole in which the rear side of the inner wall surface is widened at the rear side of the stepped portion 61B1. The stepped portion 61B1 of the engaging hole 61B is adapted to engage an engaging portion 92 on the rear end side of the transmission member 90, which will be described later. The step portion 61B1 includes a point of action on which the tensile force of the transmission member 90 acts.
According to the illustrated example, the two locking holes 61B are provided on both sides in the radial direction and are selectively used, but one of them can be omitted.

The bottom wall portion 62 is provided in the shape of a rectangular plate as a rear end wall of the tubular portion 61, has a through hole 62A in which the lead screw 40 is loosely inserted, and a radial direction passing through the center of the through hole 62A. A pair of pressing protrusions 62B, 62B that are pressed against the rear end surface of the nut 50 fitted in the nut holder 60 are provided on both end sides.

The pair of pressing protrusions 62B and 62B are arranged at axially symmetrical positions with the lead screw 40 as the center. Each of the pressing protrusions 62B is a ridge in which a cross section of which the outer surface is convex curved (semicircular in the illustrated example) is continuous in the radial direction.

Further, the front support member 70 includes a bearing portion 71 through which the front shaft portion 44 of the lead screw 40 is inserted, and an annular base portion 72 integrally fixed to the outer peripheral side of the bearing portion 71.

The bearing portion 71 is a bearing member that rotatably supports the front shaft portion 44, the outer peripheral portion of which is fitted to the front end side of the annular base portion 72 and is supported by the annular base portion 72 so that it cannot rotate and cannot move forward and backward.

The outer peripheral portion of the annular base portion 72 is fitted to the inner peripheral surface of the front end side of the case 20 and is fixed by a fastener 73 (for example, a screw or a bolt) so that it cannot rotate and cannot move back and forth. A through hole 72A for loosely inserting the transmission member 90 is provided at a position corresponding to the locking hole 61B of the nut holder 60 on the radial end side. According to the illustrated example, two through holes 72A are provided on both sides in the radial direction, but it is possible to omit one through hole 72A through which the transmission member 90 is not inserted.

The guide members 81 are fixed between the rear support member 30 and the front support member 70, and according to the illustrated example, a pair of guide members 81 are provided at axially symmetrical positions on both sides in the radial direction (FIGS. 1 and 2 ). reference).
Each guide member 81 is formed in a shaft shape and is slidably fitted in the guide groove 61A of the nut holder 60. The rear end and the front end of each guide member 81 are fitted and fixed to the annular base 32 of the rear support member 30 and the annular base 72 of the front support member 70, respectively.
With these configurations, the pair of guide members 81, 81 holds the nut holder 60 so as to slide in the front-rear direction without rotating.

Further, the transmission member 90 is integrally configured of a long flexible wire 91 and a locking portion 92 fixed to one end side of the wire 91.
The locking portion 92 is locked to the step portion 61B1 in the locking hole 61B of the nut holder 60. The wire 91 connected to the locking portion 92 is inserted through the front side of the locking hole 61B and the through hole 72A of the front support member 70 and guided to the front of the screw feeding device 1.

Next, the characteristic operation and effect of the screw feeding device 1 having the above configuration will be described in detail.
When the lead screw 40 is rotated in the screwing direction with respect to the nut 50 by energizing the rotary drive source 10, the nut 50 and the nut holder 60 retract along the guide member 81 and pull the transmission member 90 rearward.
At this time, a forward external force along the screw axis direction is applied to the step portion 61B1 (point of action) in the locking hole 61B of the nut holder 60. Therefore, the nut holder 60 is pulled forward by the transmission member 90 at a position that is offset in the radial direction, but the tilt is suppressed by the guide member 81. Then, in this state, the external force is applied to a line orthogonal to the central axis of the rear end surface of the nut 50 via the pair of pressing protrusions 62B and 62B.
Therefore, it is prevented that the nut 50 is inclined due to the tension of the transmission member 90 applied to the position deviated in the radial direction to increase the frictional resistance between the nut 50 and the lead screw 40, and the nut 50 and the nut holder 60 are smoothly advanced straight. It is possible to exercise, and it is possible to improve power transmission efficiency and durability.

Further, FIG. 7 shows an example of a driving device including the screw feeding device 1 having the above-described configuration.
This drive device 100 has a case 110 in which a rotary drive source 10, a screw feed device 1 and a transmission member 90 having the above-described configuration, a movable lens 120 pulled by the transmission member 90, and a movable lens 120 pulled by the transmission member 90. A biasing member 130 (a coil spring in the illustrated example) that biases in a direction opposite to the direction, a fixed lens 140 fixed to the case 110 so as to be located on the optical axis of the movable lens 120, a fixed lens 140, and An image pickup element 150 that picks up an image of a subject outside the case 110 via the movable lens 120 is provided, and constitutes a camera unit.
According to this camera unit, the movable lens 120 can be smoothly moved linearly due to the structure of the screw feeding device 1 described above.

In addition, the screw feed device 1 having the above-described configuration can be applied to, for example, a mobile device including a mobile information terminal, a prosthetic hand or artificial joint, an industrial device, a medical device, and other devices.

In the above embodiment, the pressing protrusion 62B is provided on the bottom surface in the nut holder 60, but as another example, in place of the pressing protrusion 62B, a pressing protrusion is provided on the rear end surface of the nut 50. It is also possible to

Further, in the above-described embodiment, as a particularly preferable aspect, each pressing projection 62B is a ridge that makes line contact with the rear end surface of the nut 50, but as another example of the pressing projection 62B, point contact with the rear end surface of the nut 50 or It is also possible to use protrusions that are in contact with each other in a minute area.

Further, in the above embodiment, the guide member 81 is a pair of shaft-shaped members as a particularly preferable mode, but as another example of the guide member 81, a mode in which a single or three or more shaft-shaped members are used, or a guide member is used. It is possible to omit 81 and guide the outer peripheral surface of the nut holder 60 in the front-rear direction by the inner peripheral surface of the case 20, or use another linear guide mechanism.

Further, according to the above-described embodiment, the transmission member 90 is pulled by the nut holder 60 toward the rotary drive source 10, but as another example, the front and rear directions of the nut 50 and the nut holder 60 are reversed. It is also possible to adopt a configuration in which the transmission member 90 is pulled toward the side opposite to the rotational drive source 10.

Further, according to the above-described embodiment, the external force acts on the point of action (the step portion 61B1 according to the illustrated example) via the wire 91, but as another example, the wire 91 is omitted and the external force is directly applied. It is also possible to adopt a mode in which the nut holder 60 acts on the action point.
As an example, it is also possible to adopt a mode in which an elastic member (for example, a spring) that presses the nut holder 60 against the nut 50 is provided, and the elastic force (external force) of the elastic member acts on the action point of the nut holder 60. ..

In addition, according to the above-described embodiment, the force in the front-rear direction is applied to the radially offset position of the nut holder 60 via the flexible wire 91. It is also possible to replace the member with.

Although the embodiments of the present invention have been described in detail above, the specific configuration is not limited to these embodiments, and even if there is a design change or the like within a range not departing from the gist of the present invention, Included in the invention. Further, the respective embodiments described above can be combined by diverting each other's technology as long as there is no particular contradiction or problem in the purpose and configuration.

1: Screw feeding device 10: Rotational drive source 20: Case 30: Rear side supporting member 40: Lead screw 50: Nut 60: Nut holder 61B: Locking hole 61B1: Step portion (point of action) 62B: Pressing protrusion 70: Front side Support member 81: Guide member 90: Transmission member 100: Drive device

Claims (5)

A drive-rotating lead screw, a nut screwed to the lead screw, a nut holder that non-rotatably supports the nut and is pressed against the nut by an external force along the screw axis direction, and does not rotate the nut holder. A guide member for guiding in a straight direction along the screw axis direction,
Of the nut and the nut holder, one of the members is provided with a pair of pressing protrusions that are pressed by the other member on both sides in the radial direction with the lead screw placed on the center side,
The screw feeding device, wherein the nut holder has an action point for receiving the external force at one end side in a radial direction intersecting with the arranging direction of the pair of pressing protrusions. 2. The screw feeding device according to claim 1, wherein each of the pressing protrusions is a protrusion having an outer surface having a convex curved cross section that is continuous in the arrangement direction. The screw feed device according to claim 1 or 2, wherein an action point of the nut holder is provided on a straight line substantially orthogonal to a direction in which the pair of pressing protrusions are arranged. 4. The guide member is formed in a shaft shape, and penetrates the nut holder in the axial direction of the screw on the end side in the arrangement direction of the pair of pressing protrusions. The described screw feeder. A drive device comprising the screw feeding device according to claim 1.

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