JPS58187642A - Screw feed controlling device equipped with self-aligning mechanism - Google Patents

Abstract

PURPOSE:To accomplish the smooth feeding of a feed nut without over-restrcting the feed nut in spite of geometrical errors such as off-set of axes in the directions of a guide and a feed screw shaft and of inclination wherein by a structure wherein the feed nut is supported by a gimbal mechanism and yet axial clearances are provided. CONSTITUTION:The self-aligning functions toward the off-set of the axes in the directions of the guide and the feed screw comprises rolling-shifting trunnions 10 axially through balls 15 against the off-set component element both in the directions of V-V' and H-H' and inclining the mechanism by utilizing the balls 15 as roller bearing with the trunnions 10 as rolling center against the inclination component element.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides rotational motion i[11! i! This invention relates to a screw feeding device with an automatic centering mechanism that converts motion into motion, and in particular to an ultra-precision screw feeding device flIK that requires high linear positioning accuracy and 1111 movement with minimal speed fluctuation.

(b) An example of a screw feeding device that converts rolling motion t' into linear motion is shown in FIGS. 1 and 2.

The screw feed device shown here rotates the feed screw 2 by rotational motion from a motor 1 or the like, and restrains the feed nut 3 engaged with the screw thread of the feed screw 2 in the (b) rotation direction.
The feed nut 3 is configured to move in the force direction of the center of the rotation axis of the feed screw 2 [E-F'.

In this case, the slider is used to constrain the rotational direction of the feed nut 3 and to guide the axial movement associated with kneading.

4 and guide rails 5, and rolling elements such as rollers 6 to completely reduce the load resistance force are also adopted as necessary.

In such a screw feeding device, the moving direction F - F' of the feeding nut 3 and the guiding direction GHG'H (
If Gv G'v (horizontal direction) and G'v (vertical direction) do not match, pitch errors and load torque fluctuations peculiar to the screw feeder S will occur, as shown in FIGS. 3 to 6.

This is caused by an undesirable motion component in the radial direction relative to the main motion component in the linear movement direction FF' of the feed nut 3, as shown in FIG. This radial direction movement is caused by the deviation between the feed screw center F-F' and the guide direction G-a in both the horizontal direction H-H' and the straightening direction v-v'.

That is, as shown in Figs. 4 and 5, assuming that the guiding direction G - G''k is an ideal straight line, the mounting error pressure of the feed screw 2 causes the inclined state shown in Fig. #4 and the feed screw 2.
The screw is fed in the curved state shown in FIG. 5 depending on the axis (straightness) of the screw. At this time, since the feed nut 3 operates as if it were integrated with the sliver 4, a change occurs in the state of engagement between the feed screw 2 and the feed nut 3.

As a result, a pitch error due to the misaligned lid e in the guide direction GG' and the linear motion direction F-1v and an accumulated pitch error due to the inclination θ occur. The amount of linear movement S of the feed nut 3 relative to the rotational speed H of the feed screw 2 is shown in Figure 6. Therefore, in Figs. 1 and 2, in the π Kusu feed screw device VC, the axis F-)7 of the feed screw 2 and the guiding direction G-G' are set in μm.
Matching below the order is difficult due to the level of accuracy of each individual part.

Therefore, for the purpose of ultra-tight self-alignment of the woodcutter, a means has conventionally been used that does not over-restrict the feeding pad 3, as shown in FIGS. 7 to 10.

In these figures, the one shown in FIGS. 7 to 8 is one in which the mechanism for preventing the feed nut 3 from sticking to the guide rail 5 is performed by two support rollers 7, and the one shown in FIG.
FIG. 7 is a plan view of FIG. 7; This conventional technology supports [
- The spring constant of the shank spring 8 that holds the roughness affects the rigidity in the feed direction, and a conical force acts on the feed nut 3, so it is used for light load applications.

The one shown in FIGS. 9 and 10 is supported by the feed nut 31r trunnion structure, and FIG. 10 is a plan view of FIG. 9. In this prior art V, since the trunnion bin 10 is installed in the horizontal direction H-H',
Guide direction (horizontal) GM (Feed screw 2 for J'H
The axial center (horizontal) of the feed screw 2 with respect to the center deviation 1°e of the axis (horizontal) and the guiding direction (vertical If) Gv-αH (
1flL) Fv F'yiQ) #I It is possible to prevent over-restriction corresponding to the slope amount Q, and the dog nut holder is arranged so that it is located at the center of the two trunnion bins 10 or the center of the feed nut 3. 11 is shaped to hold the center of the feed nut 3, and has a special spacing that prevents the conical sword from acting on the feed nut 3.

However, due to the fitting clearance of the trunnion bin 10, a dead zone may occur in the feeding direction.

That is, as shown in FIG. 9, since there is a clearance tqt between the retaining holes of the trunnion bin 10 and the Nand holder 11, play in the feeding direction occurs.

One object of the present invention is to provide a screw feeding device 1i with a self-aligning structure that is precise and unaffected by errors in the feeding direction and the guiding direction, and which eliminates the disadvantages of the prior art described above.

The present invention uses a feed screw mechanism as a means for converting rotational motion into m-line motion, and uses a trunnion machine to support the feed nut.
using orthogonal rotation axes 08. 710 for rotation function of θa
Furthermore, it has a structure that allows axial movement of 0x and θ, and furthermore, a plurality of balls are arranged between the trunnion bin and the engagement hole.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

First, the structure and operation of the trunnion mechanism, which is a basic element of the present invention, will be explained using FIG. 11.

The trunnion mechanism itself has two orthogonal rotational axes 01., like a compass. This is a technique that has been conventionally used to obtain an arbitrary inclination angle with respect to a secondary redundant plane by utilizing the property of θa.

In FIG. 11, a pair of trunnion pins 10 are disposed on the angle shifter 12, and the trunnion pin 10 has a hole that engages with the trunnion pin 10, and another pair of trunnions is provided at a position perpendicular to the retaining hole. An inner holder 13 with a bin 10 disposed thereon is disposed, and an outer holder 14 having a hole that engages with the trunnion bin 10 is disposed.

In this case, the angle mover 12 can tilt with respect to the inner holder 13 with the rotation axis in the θA direction, and the inner holder 13 can tilt with the rotation axis in the θA direction with respect to the outer holder 14. As a result, the angle mover 12 has an inclination or EJ function with each of Uy and 08 as the rotation axis and E7, and can be moved to any angle with respect to the two-dimensional plane.

Next, we will discuss the 9th and 12th requirements for using the above-mentioned trunnion mechanism with the holding function of the feed nut 3.
This will be explained using FIGS. 16 to 16.

The conventional trunnion mechanism that attaches is the 0□ and 0a axis.
Each of these uses a tilting function centered on the shaft, but in order to use the stiffness as a holding function for the feed nut 3, in addition to the tilting function described above, a misalignment that can be moved in the axial direction of θ8 and 0a is required. functionality is required.

Therefore, in the present invention, gaps are provided between the feed nut 3 and the inner holder 13 and between the inner holder 13 and the outer holder 14 to allow for axial movement.

Next, if there is a gap q between the trunnion pin lO and the engagement hole in Fig. 11, there will be play in the feed direction in the feed screw mechanism, which will create a dead zone on the positioning hllllJQl. Some means of integration are necessary. Therefore, in the present invention, a ball 15 is interposed between the trunnion bottle 10 and the retaining hole.

As shown in FIG. 13, the ball 15 can be used directly while being held in a retainer 16, or as shown in FIG. As shown in the figure, when the ball 15 is placed in a circulation type housing 17 without using the retainer 16', the surrounding material and the degree of preload are affected by the special characteristics of the holding method of the ball 15 in the case of fi+:r+-. Furthermore, it is selected depending on the required accuracy level.

FIG. 16 shows the basic configuration of the present invention.

In FIG. 16, a pair of trunnion bins 10t are disposed on the feed nut 3, have a hole that engages with the trunnion bin 10, and another pair of trunnion bins are disposed perpendicularly to the engaging hole. Inner Holter 13 with 10 installed
1, and an outer holder 14 having a hole that engages with the trunnion bin 10 is provided. Further, between the feed nut 3 and the inner holder 13, and between the inner holder 13 and the outer holder 14,
At the same time, a ball 15 is interposed between the two pairs of trunnion bins 10 and their respective retaining holes without a gap in the radial direction.

As a result, the guiding direction G-G' and the axis of the feed screw F -
The self-alignment function for the misalignment of F' includes rolling movement via the ball 15 in the axial direction of the trunnion bin 10 for the element of misalignment C in both the v-v' and H-H'directions;
The element of inclination θ is realized by inclining the ball 15 centered on the trunnion bin 10 as a rolling bearing.

Figures 17 to 19Fi are a series of third angle projection views showing a specific embodiment of the present invention.

In this embodiment, a ball screw 18t is used as a feed screw, and a ball nut 19 is used in pairs (double).
Preload is set using the spacer 20. A pair of trunnion pins 10 are arranged in the spacer 20, and the trunnion pins 10 have an engagement hole in which a ball 15 with a retainer 16 is interposed, and another pair is provided at a position orthogonal to the engagement hole. Inner holder A21 and inner holder B2 in which the trunnion bin 10 of
2, and the inner holder A21 and the inner holder B22 are connected to the positioning pin 23 with screws after the ball 15 is assembled therein. Furthermore, a pair of split-type soto-holders 24 are assembled into a pair of trunnion bins 10 disposed in the inner holder A21 with balls 15 with retainers 16 interposed therebetween, thereby forming a self-NJJ alignment mechanism.

Furthermore, a split type sotoholder 24 is attached to the slider 4, and the slider 4 is guided in its axial movement by a roller guide 25 between the guide rails 5.

With the configuration described below, the rotation of the motor 1 is transmitted to the ball screw 18 via the shaft joint 26, and the ball screw 18 is supported by the bearing 27 and rotates, so that the ball nut 19 moves in the axial direction.

As is clear from the above explanation, according to the present invention, (1) Even if there is a difference in the shape of the center spring or inclination in the guiding direction and the axial direction of the feed screw, the feed nut can be smoothly tightened without being overly constrained. You can only get the shipping. In other words, an automatic alignment function can be realized.

(2) By applying preload to the roller bearing, only play occurs in the feed direction. In other words, a dead zone prevention function can be realized.

(3) Since the load is applied to the center of the feed nut, no conical external force acts on the feed nut. That is, it is possible to realize a negative application action to the center of the screw. As it has the following effects, it is possible to obtain a precise linear feed function.

[Brief explanation of drawings]

Figures 1 and 2 are schematic diagrams showing the general configuration of a conventional screw feeding device, Figures 3 through 6 are explanatory diagrams showing error factors of the conventional screw feeding device, and Figures 7 and 8 are The figure is a pair of third angle projection views showing an example of the prior art, Figures 9 to 10 are a pair of third angle projection views showing other examples of the prior art, and Figures 11 to 15 are the main FIG. 16 is a partial sectional view showing the basic configuration of the invention, and FIGS. 17 to 19 are a pair of third angle projection views showing an embodiment of the invention. be. DESCRIPTION OF SYMBOLS 1... Motor, 2... Feed screw, 3... Feed nut, 10... Trunnion bin, 13... Inner holder,
14...Outer holder, 15...Ball, 16...Retainer, 17...Housing, 21.22...Inner holder, 23...Positioning lever R No. 17 1! ! 78th country

Claims (1)

[Claims] 1. In a screw feed device that converts rotational motion into linear motion, the feed nut is supported by a screw mechanism, and in addition to the rotational action of the Q and Q axes, % Q K and Q are used.
1. A screw feeding device with an automatic centering mechanism, which is characterized by: (1) providing an axial clearance to enable movement in the axial direction of the shaft; 2. In a screw feeding device that converts rotational motion into linear motion, a gimbal mechanism that connects the feeding nut, an inner holder, and an outer holder with a support pin and a support hole is used as a support means for the feed nut, and the support bin and A screw feeding device with a self-aligning mechanism that uses a ball interposed between support holes.