JPH10151543A - Forming machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease rotation inertia moment by decreasing the outside diameter of a ball nut and the outside diameter of the internal rolling part of a bearing. SOLUTION: Setting is effected such that a slight clearance is provided between the inner peripheral surface of a sleeve 3 and the outer peripheral surface of a ball screw 5 advancing and reversing in a sleeve 3, and the outside diameter of the sleeve 3 is reduce in a range of a value enough to allow strength. Thus, a radius to the internal rolling part 2a of a bearing 2 rotated integrally with the sleeve 3 is reduced to a low value. When rotation of a motor is transmitted to a ball nut 4 through a proper rotation transmission mechanism, a ball nut 4 is rotated together with the sleeve 3 pivotally supported at the bearing 2, and this constitution advances or moves backward the ball screw 5 and causes advance drive or backward movement drive of a coupling member 6 and a reciprocating member 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding machine provided with a mechanism for converting rotation to linear motion by a ball nut and a ball screw. More particularly, the present invention relates to a molding machine that supports the outer periphery of a ball nut via a bearing and rotates the ball nut. The present invention relates to a rotation-to-linear motion conversion mechanism for moving a ball screw forward and backward.

[0002]

2. Description of the Related Art It is known that a molding machine such as an injection molding machine uses a motor such as an electric servomotor as a driving source of a reciprocating mechanism. In such an injection molding machine, the rotation of the motor is controlled by a ball screw. Rotation by a ball nut and → linear motion Conversion mechanism converts the linear motion into linear motion, and reciprocating members (for example, a member for moving the screw forward and backward in the case of the injection system, moving the movable die plate forward and backward in the case of the mold opening and closing system) (In the case of an eject system, a member for moving the eject member forward and backward).

In the case of using the rotation-to-linear motion conversion mechanism as described above, a configuration in which a ball screw is pivotally supported and the ball nut is moved forward and backward by rotation of the ball screw, or a configuration in which the ball nut is pivotally supported and used. Any of the configurations in which the ball screw is moved forward and backward by the rotation of.

When the latter rotation-to-linear motion conversion mechanism is adopted, a ball nut that transmits the rotation of the motor via an appropriate rotation transmission mechanism is mounted on an appropriate support member via a bearing (such as a ball bearing). Must be rotatable.

FIG. 4 is a simplified explanatory view showing a conventional configuration of the latter rotation-to-linear motion conversion mechanism. In FIG. 4, reference numeral 51 denotes a support member; 52, a ball nut which is rotatably held by the support member 51 via a bearing 53 and cannot move in the axial direction; 54, a ball screw screwed to the ball nut 52; Connecting member 5 to ball screw 54
6 is a reciprocating member (driven body) connected through the radiator 6.

As shown in FIG. 4, in the conventional configuration,
The ball nut 52 has an inner rotation portion 53a of the bearing 53 fitted around its outer periphery, and the outer rotation portion 53b of the bearing 53 is fitted to the inner surface of the holding hole of the support member 51. A rolling element 53c such as a ball positioned between the inner rotation part 53a and the outer rotation part 53b has a structure in which the rolling element 53c is rotatably supported so as to smoothly rotate with little frictional resistance.

[0007]

As is well known, the ball nut 52 needs a circulating portion for circulating the ball between a ball screw (screw shaft) and the nut infinitely. The type using a return tube as the circulation part is suitable for mass production and is relatively inexpensive, and is therefore frequently used in molding machines. However, since the circulating portion such as the return tube bulges outward, the cross section of the circulating portion is not a circular shape in this state, so that a bearing 53 is provided on the outer periphery of the ball nut 52 as shown in FIG. In order to fit each other, a thick cylindrical portion that covers a circulation portion such as a return tube must be provided on the ball nut 52.

However, the ball nut 52 having a thick cylindrical portion that covers the circulating portion as described above must have a large outer diameter, and inevitably has a bearing fitted on the outer periphery of the ball nut 52. The diameter of 53 also increases. For this reason, the rotation D represented by the radius D to the adduction portion 53a of the bearing 53 that rotates integrally with the ball nut 52 and the weight G obtained by adding the weight of the ball nut 52 and the weight of the adduction portion 53a of the bearing 53. Moment of inertia G of the body (ball nut 52 and adduction 53a of bearing 53)
D ² is, is inevitably increased just more than a certain degree.

Therefore, the rotating member (the ball nut 52 and the inner rotating portion 5 of the bearing 53) driven to rotate by the motor is provided.
Since the rotation inertia moment GD ² in 3a) is large, there is a problem with transient response at the time of converting the rotary motion into linear motion (rising / falling characteristic), in the machine high-speed response is required (molding machine) , Which is a factor that hinders performance improvement.

[0010] The present invention has been made in view of the above points,
It is an object of the present invention, and supported the ball nut, in rotation → linear motion conversion mechanism configured to reverse before the ball screw in the rotation of the ball nut, to reduce the rotational inertia moment GD ^2, I or more, transient An object of the present invention is to improve responsiveness (rise / fall characteristics) and improve machine performance.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a ball nut which is rotated by a rotating force of a motor, and is axially moved by being screwed to the ball nut by rotation of the ball nut. In a molding machine including a ball screw and a driven body that linearly moves together with the ball screw under the axial propulsion of the ball screw, the outer diameter of the ball nut is reduced to a value within a range where strength is allowed, and At one end of the ball nut, there is provided a sleeve that rotates integrally with the ball nut and allows the ball screw to loosely insert into the inside of the ball nut. The outer diameter of the ball nut and the outer diameter of the adduction portion of the bearing are reduced by holding the outer periphery of the ball nut rotatably via a bearing. Constructed.

[0012] Further, the present invention achieves the above object,
A ball nut that rotates by receiving the rotational force of the motor, a ball screw that is screwed to the ball nut and moves in the axial direction by the rotation of the ball nut, and a driven that linearly moves with the ball screw by receiving the axial driving force of the ball screw In a molding machine provided with a body, while reducing the outer diameter of the ball nut within a range where strength is allowed, forming an annular groove in which a rolling element of a bearing fits on the outer periphery of the ball nut, The outer circumference of the ball nut is used as the inner rotation part of the bearing, so that the outer diameter of the inner rotation part of the bearing is reduced.

[0013]

Embodiments of the present invention will be described below. FIG. 1 is a simplified explanatory view showing a configuration of a rotation → linear motion conversion mechanism in a molding machine according to a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a support member, 2 denotes a bearing, 2a denotes an inner turning portion of the bearing 2, 2b denotes an outer turning portion of the bearing 2, 2c denotes a rolling element such as a ball of the bearing 2,
3 is a sleeve (cylindrical body), 4 is a ball nut, 4a is a flange portion of the ball nut 4, 4b is a return tube of the ball nut 4, 5 is a ball screw, 6 is a connecting member, 7 is a reciprocating member (driven body). It is. Also, the reciprocating member 7
In the case of the injection system, a member for moving the screw back and forth, for the mold opening and closing system, a member for moving the movable die plate back and forth, and in the case of the eject system, a member for moving the eject member back and forth, Is equivalent to

In this embodiment, the sleeve 3 is rotatably held by the support member 1 via the bearing 2 so as not to move in the axial direction. That is, the sleeve 3 is provided on its outer periphery with the adduction portion 2 of the bearing 2.
The sleeve 3 is positioned between the inner rotation part 2a and the outer rotation part 2b of the bearing 2 by fitting the outer rotation part 2b of the bearing 2 to the inner surface of the holding hole of the support member 1. It is supported by a rolling element 2c such as a ball so that it can rotate smoothly with little frictional resistance. A small clearance is set between the inner peripheral surface of the sleeve 3 and the outer peripheral surface of the ball screw 5 that moves back and forth in the sleeve 3, and the outer diameter of the sleeve 3 has an allowable strength. The diameter is reduced within the range. Therefore, the adduction portion 2 of the bearing 2 that rotates integrally with the sleeve 3
The radius D up to a is much smaller than the configuration of FIG.

A ball nut 4 is integrally attached to one end of the sleeve 3 so as to be coaxial (for example, integrated by bolting or the like), and a ball screw 5 is attached to the ball nut 4. It is screwed. Therefore, when the rotation of a motor such as an electric servomotor is transmitted to the ball nut 4 via an appropriate rotation transmission mechanism, the ball nut 4 rotates together with the sleeve 3 supported by the bearing 2, thereby causing the ball screw 5 to rotate. Moves forward or backward, and the connecting member 6 and the reciprocating member (driven body) 7 are driven forward or backward.

The outer diameter of the ball nut 4 is reduced within the range permitted by the strength, and the ball nut 4 is formed by projecting the return tube 4b as a ball circulating portion to the outside. It is a mold ball nut. FIG. 2 is a cross-sectional side view of a main part of FIG. 1, showing a state in which the return tube 4b projects outside. Therefore, the substantial radius D of the ball nut 4 is significantly smaller than that of the configuration shown in FIG.

In the present embodiment, the substantial radius of the ball nut 4 and the radius of the bearing 2 rotating integrally with the sleeve 3 up to the adduction portion 2a are significantly reduced as described above. Here, in the present embodiment, the total weight of the rotator obtained by adding the weight of the ball nut 4, the weight of the sleeve 3, and the weight of the adduction part 2a of the bearing 2 is the rotation in the configuration of FIG. The weight is substantially equal to the total weight of the body (the weight obtained by adding the weight of the ball nut 52 and the weight of the adduction portion 53a of the bearing 53), and although the weight cannot be reduced, the rotational inertia indicated by the above-mentioned GD ² In the present embodiment, the moment can be greatly reduced as compared with the configuration shown in FIG.

Therefore, in the rotation-to-linear motion conversion mechanism of this embodiment, the rotational inertia moment GD ²
Is small, the transient responsiveness (rising / falling characteristics) when the rotary motion is converted to the linear motion is greatly improved, and high-speed responsiveness is achieved. Therefore, injection performance, mold opening / closing performance, and eject performance are improved. For example, high-precision molding of a thin molded product can be easily achieved by shortening the injection rise time. Further, shortening of the rise time and fall time of each of the injection, mold opening and closing, and ejecting operations contributes to shortening of the molding cycle.

In the present embodiment, the sleeve 3 and the ball nut 4 are formed as separate members. However, the sleeve 3 and the ball nut 4 may be formed as a completely integrated member.

Next, a second embodiment of the present invention will be described.
FIG. 3 is a simplified explanatory view showing a configuration of a rotation → linear motion conversion mechanism in a molding machine according to a second embodiment of the present invention.

In FIG. 3, reference numeral 11 denotes a support member, 12 denotes a bearing, 12b denotes an abduction part of the bearing 12, 12c denotes a rolling element such as a ball of the bearing 12, 13 denotes a ball nut, and 13a denotes an outer periphery of the ball nut 13. The formed annular groove, 13b is a return tube of the ball nut 13, 1
Reference numeral 4 denotes a ball screw screwed into the ball nut 13. In FIG. 3, members driven forward and backward by the ball screw 14 are not shown.

In the present embodiment, the ball nut 13
The rolling element 12c of the bearing 12 is fitted into the annular groove 13a formed on the outer periphery of the ball nut 13 so that the outer peripheral part of the ball nut 13 is used as the inner rotation part of the bearing. That is, the rolling element 12 c of the bearing 12 is rotatably fitted in the annular groove 13 a of the ball nut 13.
The ball nut 13 is fitted to the inner surface of the holding hole of the support member 11, whereby the ball nut 13 is subjected to frictional resistance by a rolling element 2 c such as a ball located between the outer periphery of the ball nut 13 and the abduction part 2 b of the bearing 2. It is pivotally supported so that it can rotate smoothly.

Also, in the present embodiment, the outer diameter of the ball nut 13 is reduced as far as the strength permits, and the ball nut 13 of the present embodiment also has a return function as a circulating portion of the ball. The tube 13b is a ball nut of a tube projecting type protruding outside.
However, the return tube 13b is provided at a position avoiding the annular groove 13a (that is, the bearing 12). Accordingly, the radius D of the bearing 12 that rotates integrally with the ball nut 13 to the adduction portion, in other words, the substantial radius D of the ball nut 13 is significantly smaller than that of the configuration of FIG. It has become.

In this embodiment, the ball nut 13
Since the annular groove 13a is formed on the outer circumference of the ball nut 1 in comparison with the radius of the rotating body of the first embodiment described above.
Although the substantial radius D of 3 is slightly larger, it is much smaller than the configuration of FIG. Further, since the outer peripheral portion of the ball nut 13 is used as the adduction portion of the bearing, the weight of the rotating body is reduced by the amount that the adduction portion can be omitted, compared to the configuration of FIG. 4 and the first embodiment. Can be smaller.

[0026] Thus, also in this embodiment, the rotational moment of inertia represented by the GD ² can be significantly reduced, it exhibits the same effect as the first embodiment described above.

[0027]

According to the present invention as described above, according to the present invention, and pivotally supports the ball nut, the rotational → linear motion conversion mechanism configured to reverse before the ball screw with rotation of the ball nut, small rotational inertia moment GD ² As a result, the transient response (rising / falling characteristics) can be improved, and the machine performance can be improved.

[Brief description of the drawings]

FIG. 1 is a simplified explanatory view showing a configuration of a rotation → linear motion conversion mechanism in a molding machine according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of FIG.

FIG. 3 is a simplified explanatory diagram showing a configuration of a rotation → linear motion conversion mechanism in a molding machine according to a second embodiment of the present invention.

FIG. 4 is a simplified explanatory view showing a configuration of a rotation → linear motion conversion mechanism in a conventional molding machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 support member 2 bearing 2a bearing inner turning part 2b bearing outer turning part 2c bearing rolling element 3 sleeve (cylindrical body) 4 ball nut 4a ball nut flange part 4b ball nut return tube 5 ball screw 6 connecting member 7 Reciprocating member (driven body) 11 Support member 12 Bearing 12b Abduction part of bearing 12c Roller of bearing 13 Ball nut 13a Annular groove of ball nut 13b Return tube of ball nut 14 Ball screw

Claims (2)

[Claims] 1. A ball nut which rotates by receiving a rotation force of a motor, a ball screw which is screwed to the ball nut and moves in an axial direction by rotation of the ball nut, and a ball screw which receives an axial propulsion force of the ball screw to rotate together with the ball screw. A driven body that moves linearly, wherein the outer diameter of the ball nut is reduced within a range allowed by strength, and one end of the ball nut is integrally rotated with the ball nut. A sleeve that allows the ball screw to loosely insert therein is provided, and the outer diameter of the sleeve is reduced within a range allowed by strength, and the outer periphery of the sleeve is rotatably held via a bearing. Wherein the outer diameter of the ball nut and the outer diameter of the adduction portion of the bearing are reduced. 2. A ball nut which rotates by receiving a rotating force of a motor, a ball screw which is screwed to the ball nut and moves in an axial direction by the rotation of the ball nut, and a ball screw which receives an axial propulsive force of the ball screw together with the ball screw. A driven body that moves linearly, wherein the outer diameter of the ball nut is reduced within a range allowed by strength, and a rolling element of a bearing fits on the outer periphery of the ball nut. A molding machine wherein an outer diameter of an inner rotation portion of the bearing is reduced by forming an annular groove and making an outer peripheral portion of the ball nut an inner rotation portion of the bearing.