JPH0238741A - Backlashless feed screw - Google Patents

Abstract

PURPOSE:To eliminate backlash as well as to make manufacturing cost inexpensive by dividing a feed nut into two sections in the axial direction, letting a countersunk screw be coupled in between them while being inserted, and thereby letting both of the nut sections be connected together by use of whirl-stop fasteners. CONSTITUTION:A feed nut 2 which is engaged with a threaded bar 1, is divided into tow nut sections 2-1, and 2-2 so that a disc spring 5 is coupled in between them while being inserted. The disc spring 5 is made of an elastic metal the center section 5a of which the threaded bar 1 is penetrated through. Each nut section 2-1 and 2-2 is pressed outward with pressure one another by the contersunk spring 5. The flanges 2a and 2b of the nut sections 2-1 and 2-2 are connected by whirl-stop fasteners 7-1 and 7-2. This constitution therefore eliminates backlash, thereby making it possible to make manufacturing cost inexpensive.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lead screw without backlash.

[Prior Art] In the manufacture of products such as electronic parts that require precision processing, feed tables are often used to move workpieces. There are various methods for moving the table, but conventionally a ball screw is used for precise movement.

FIG. 3 shows an axial cross section of the ball screw. A feed nut 2 is fitted onto a threaded rod 1 with their threads aligned, balls 3 are inserted into the grooves formed by the valleys of each other, and a return groove 4 for circulating the balls is provided in the nut. When the threaded rod rotates, the balls move along and circulate through the return groove. The threaded rod and the feed nut mesh well with each other due to the balls, and there is no play between them, so that highly accurate feeding without backlash can be achieved.

[Problem M to be solved] Although the ball screw described in item h is excellent as a high-precision feeding mechanism, the mechanism is somewhat complicated and therefore the price is not low. On the other hand, depending on the use of the feeding table, such highly accurate feeding may not be required. However, a feed screw that simply combines a threaded rod and a nut cannot be used because the backlash is excessive and the positioning accuracy is poor.

This invention has been made in view of the above points, and provides an inexpensive feed screw that has no backlash or has negligible backlash by processing the nut for a feed screw using a +11 threaded rod and a nut. The goal is to do so.

[Means for Solving the Problems] The present invention provides a backlash-less feed screw with no or negligible backlash,
A feed nut that fits onto a threaded rod is divided into two parts in the axial direction, and a disc spring that presses the two nut parts outward from each other is inserted between the two divided nut parts. It goes around the N1-metal and connects it with a fitting.

[Effect] Figure 1(a) shows the action of the disc spring in the above structure.

This will be explained using (b). In figure (a), the screw Fli
The feed nut 2 that fits into the t1 has two nut parts 2-
Otori.

It is divided into 2-2 parts, and a disc spring 5 is inserted between them. The disc spring 5 is made of an elastic metal and has the shape shown in FIG. 3(b), and a threaded rod 1 is passed through a hole 5a in the center thereof. In the figure, two countersunk screws are inserted as an example, but the invention is not limited to this. Each nut portion is pressed outwardly against each other by a disc spring.

Looking at the meshing part e shown by the dotted line in Figure (a), the outer side (relative to the countersunk screw) of the thread of the nut part 2-countersans presses against the inner side of the thread of the corresponding threaded rod. . This pressing is performed on all of the meshing parts, and as long as each nut part does not rotate relative to each other, the pressing force is in the opposite direction to the two nut parts, even when the threaded rod rotates. always works. In other words, there is no backlash.

In below-L, if the two nut parts rotate in opposite directions, the pressing action of the disc spring is lost. On the other hand, although not shown in FIG. 1, both nut portions are connected by a rotation stopper to prevent relative rotation.

[Example] Figures 2(a) and 2(b) show the structure of an example of the backlashless feed screw according to the present invention.
In this case, the threaded rod 1 is supported by a bearing 11-1.112 provided on the base plate 1O, and rotated by a motor (not shown). A nut portion 2-1.2-2 obtained by dividing a feeding nut to be fitted into two parts is inserted into the threaded rod, and a countersunk screw 5-1.5-2 is inserted between them. As mentioned above, countersunk screws are
Don't limit yourself to two sheets; use as many sheets as you can to change the required pressing force.

Next, is there a rotation stopper between the flanges 2a and 2b of the nut part?
-1, 7-2 are connected.

The rotation stopper is for stopping the relative rotation of the two nut parts, but it is necessary to have a degree of freedom in the axial direction with respect to the disc spring, and for this purpose, it is fixed to one flange 2a. , the other flange 2b is penetrated freely in the axial direction. A feed table 9 is fixed to the flange 2a with a fixture 8. Due to the above structure, the two nuts PE2-1, 2-2 are pushed in opposite directions by the action of the disc spring 5 described above, and their threads are aligned with the threaded rod l.
The screw threads of the screw rod are pressed against each other, and the feed table can be moved in a small manner without backlash or with very small backlash when the screw rod rotates.

In addition, although the rotation stopper 241 was connected between the flanges in ``-'', the number of stoppers is not limited to two (and the installation method is based on the relative rotation of both nuts). If it is stopped and there is a degree of freedom in the axial direction, then Fig. 2 (a) and (b)
Of course, other methods may also be used.

[Effect of the invention] As is clear from the above explanation, the backlashless feed screw according to this invention divides the feed nut into two parts,
A countersunk screw is inserted in between, and both nuts are connected by a fitting. Although it has a simple structure, there is no backlash at all, or even if there is, it is so small that it can be ignored.
In addition, the production cost is low, and the effect that it can be used for the feeding table of various devices that meet the required feeding accuracy is unique.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are an axial sectional view and a partial perspective external view of a backlashless feed screw according to the present invention,
2(a) and 2(b) are a side view and a partial front view of an embodiment of the backlashless feed screw according to the present invention, and FIG. 3 is an axial sectional view showing the structure of the ball screw. 1...Threaded rod, 2...Feed nut, 2
-Iris, 2-2-...Nut part, 2 a + 2 b
...77 Screw, 3...Pole, 5...Countersunk screw, 6...Matching part, 8...Fixing tool, 10...Base board, 4...Return groove, 5a...・Hole for countersunk screw, 7...Rotating center, 9...Feed table, 1 plate...Bearing.

Claims (1)

[Claims] In the feed screw, the feed nut that fits on the threaded rod is divided into two parts in the axial direction, and a disc spring that presses the two nut parts outward from each other is fitted between the two divided nut parts. 1. A backlashless feed screw, characterized in that the two nut parts are connected by a rotation stopper.