JPS6241464A - Lead screw mechanism - Google Patents

Abstract

PURPOSE:To detect the abrasion degree of a nut, by providing a detecting means for detecting a spaced distance between the nut and an auxiliary nut which is threadedly engaged onto a lead screw and spaced from the former nut by a predetermined distance. CONSTITUTION:A nut 2 and an auxiliary nut 4 are threadedly engaged onto a lead screw 1, being spaced from each other by a predetermined distance. Further, a coupling member 5 is provided between the nut 2 and the auxiliary nut 4 in order to allow the auxiliary nut 4 to follow up the nut 2 in a threadedly advancing manner. There is provided a microswitch 7 as a detecting means for detecting the spaced distance between the nut 2 and the auxiliary nut 4. With this arrangement, it is possible to detect the abrasion degree of the nut 2.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a lead screw mechanism that converts rotational motion into linear motion. This invention relates to a lead screw mechanism that eliminates the problems associated with.

[Technical background of the invention and its problems]

Conventionally, this type of lead screw mechanism has been constructed as shown in FIG. That is, the nut 2 is screwed onto the lead screw 1 by a sliding contact mechanism, and the rotational motion of the lead screw (hereinafter referred to as screw) 1 is converted into linear motion and transmitted to the nut 2, and the nut 2 is held. A moving object (not shown) is linearly driven by the receiver 3.

In addition, as for the combination of the two materials, in order to maintain good sliding contact between the screw 1 and the nut 2, the screw 1 is made of hard steel such as 535C carbon steel for mechanical structures, and the nut 2 The material is PBC (phosphor bronze)
Soft materials such as

When the screw 1 and the nut 2 are properly engaged, the screw 1 having a trapezoidal thread having an angle θ is engaged with the nut 2, as shown in FIG.

On the other hand, if the object to be moved (not shown) provided in the NAND receiver 3 is a heavy object, and the object to be moved is moved up and down many times, the nut 2 on which the entire weight of the object to be moved is loaded is a soft material. , the threads begin to wear out as shown in FIG.

If the nut 2 is moved further up and down, the threads of the nut 2 will be further removed, and if it becomes unable to withstand the load of the object being moved, the threads of the nut 2 will fall off during the up and down movement, and the lead screw mechanism will no longer function. It is assumed that not only the function will be impaired, but also the moving object may be damaged and the worker may be harmed.

Here, if the amount of wear on the nut 2 can be known in advance, it is possible to prevent the above-mentioned accident.

In this case, a simple method would be to determine the amount of wear on the nut 2 based on the traveling distance of the nut 2, etc. The factors that increase the wear on the nut 2 are the material of the screw 1, the material of the nut 2, the thread number, thread machining accuracy 1 assembly performance,
(Load size fluctuates).

Since the amount of wear on the nut 2 varies depending on factors such as the rotational speed of the screw 1, the lubrication condition, and the frequency of use, it is generally impossible to know the amount of wear on the nut 2 based on the distance traveled by the nut 2, etc.

Another possibility is to remove the nut 2 from the screw 1 and have the worker directly set the nut 2 to the 71-1, but this type of lead screw mechanism is generally built into a mechanical device, so the work is easy. Furthermore, it may be impossible to disassemble the product each time you want to know the amount of wear, depending on the device that is installed.

[Purpose of the invention]

The present invention was made based on the above-mentioned circumstances, and its purpose is to provide a lead screw mechanism that can constantly detect the amount of wear on the threads of a nut and prevent problems such as falling off of the threads. It is in.

[Summary of the invention]

In order to achieve such an object, the present invention provides a lead screw mechanism in which a nut provided with a moving object is screwed onto a lead screw, and the rotational movement of the lead screw is converted into linear interlocking of the nut. an auxiliary nut that is screwed together with the nut at a predetermined distance; a connecting member that connects the auxiliary nut and the nut so that the auxiliary nut follows the nut; and The present invention is characterized by comprising a detection means for detecting a change in.

[Embodiments of the invention]

An embodiment of the lead screw mechanism according to the present invention will be described below with reference to FIG. 1, in which the same parts as in FIGS. 6 to 8 are designated by the same reference numeral 71.

In FIG. 1, a lead screw mechanism, indicated by section P in the figure, is incorporated into a device for vertically moving a top plate on which a heavy object is placed. Further, the detailed structure of the lead screw mechanism indicated by section P in the figure is shown in FIGS. 2(a) and 2(b).

In FIG. 1, a support 11 is provided upright on a base 10, and inside the support 11 are opposing lower guide rollers 12a1, 12a2 and upper guide rollers 12tz, 1.
2b2 are provided, and these guide rollers 12a+, 1
The guide rail 13 is supported by 2a, 12b1 and 12b2 and can be moved up and down. This guide rail 1
A top plate 14 is fixed to the end of 3, and a heavy object 15 is placed on this top plate 14.

The support column 11 also includes a lower bearing 16a and an upper bearing 1.
6b is provided externally, and these bearings 16a, 16b
A screw 1 of a lead screw mechanism is provided through the screw 1 of the lead screw mechanism. A nut receiver 3 that holds the nut 2 of this lead screw mechanism is fixed to a longitudinally intermediate portion of the guide rail 13. A pulley 17 is provided at the end of the screw 1, and a motor 19 having a pulley 18 on its rotating shaft is provided on the base 11.

Pulley 18 of this motor 19 and pulley 1 of screw 1
A belt 20 is passed between the screws 7 and 7, so that the rotational force of the motor 19 can be transmitted to the screw 1.

In FIGS. 2(a) and 2(b), an auxiliary nut 4 of a normal sliding contact mechanism is screwed into the screw 1 at a predetermined distance from the nut 2. Also, as a connecting member that connects the auxiliary nut 4 to the nut 2 so that the auxiliary nut 4 is threaded in conjunction with the nut 2, one end is inserted into the hole 4a of the auxiliary nut 4, and the other end is inserted into the elongated hole of the nut receiver 3. 3a, and this guide 5 is attached to the auxiliary nut 4.
A set screw 6 is provided to fix it to. Further, a microswitch 7 as a detection means for detecting a change in the distance between the nut 2 and the auxiliary nut 4 is mounted on the auxiliary nut 4 using a metal fitting 8 and a screw 9.

In the above lead screw mechanism, Fig. 2(b)
The run-out of the nut 2 shown in FIG.
A gap C is formed between the nut 2 and the nut receiver 3 to absorb the amount of water.

Figure 3 shows the elongated hole 3a and guide 5 seen in the A-A direction of Figure 2.
The vibration of Xl, X2 and Yl, Y2 of the nut 2 is absorbed by the end of the guide 5 moving in the direction of El, E2 shown in the elongated hole 3a,
The auxiliary nut 4 is adapted to spiral in response to the driving of the nut 2.

In this case, a load such as the heavy object 15 is acting on the nut 2, but the auxiliary nut 4 is only under its own weight.

FIG. 4 is an electrical circuit diagram of the device shown in FIG. 2, in which the motor 19 is connected to a power source E via a controller 21. Forward rotation/reverse rotation changeover switch Si+, upper limit switch S2, lower limit switch S3, micro switch 7, and alarm lamp 21a are wired and configured as shown.

Next, the operation of this embodiment configured as described above will be explained. That is, the motor 19 is driven by the power source E by operating the switch S1 of the controller 21. The pulley 18. is driven by the motor 19. The screw 1 is rotationally driven via a bell l-20 and a pulley 17. The nut 2 and the auxiliary nut 4 interlocked therewith are raised or lowered by the rotation of the screw 1, and the heavy object 15 is raised or lowered via the nut receiver 3 and the guide rail 13 connected to the nut 2.

In this case, as the above-mentioned vertical movement of the heavy object 15 is repeated, the threads of the nut 2 under a large load are worn out or scraped off as shown in FIG. The nut 4 hardly experiences any wear or the like.

Here, when the thread of the nut 2 is shaved off by the amount indicated by A, a drop indicated by indicated B (B-A/COS θ/2) occurs.

In this case, by predetermining the safe allowable wear iQ of the nut 2 and setting the switch operating point of the microswitch 7 to the above value G, the nut receiver 3 is adjusted to the indicated value G as shown in FIG. When descending, micro switch 7
The tip 7a of the movable element contacts the lower surface of the nut receiver 3 and is energized, and the microswitch 7 operates to cut off the power supply E and stop the rotation of the motor 19, and the alarm lamp 2 is turned on.
1a is lit to notify that an abnormality has occurred.

According to this embodiment as described above, the following effects are provided.

■ According to the present embodiment, an auxiliary nut 4 is provided which threads on the screw 1 in conjunction with the nut 2, and this auxiliary nut 4
Since the amount of movement of the nut 2 is detected by the microswitch 7, it is possible to constantly monitor the amount of wear on the threads of the nut 2, where the entire load is mainly applied. At times, an alarm is displayed and the motor 19 is stopped by the switch output of the microswitch 7, so that it is possible to prevent dangers such as the threads of the nut 2 coming off.

According to this embodiment, since the auxiliary nut 4 is provided at a step on the nut 2, even if the thread of the nut 2 falls off and the nut 2 falls, the motor 19
The screw 1 is stopped by stopping the hl
The nut 2 can be received by the supporting nut 4, thereby preventing the top plate 14 and the heavy object 15 from falling suddenly.

Next, another embodiment of the present invention will be described with reference to FIG. 5, in which the same parts as in FIG. 2 are given the same reference numerals.

That is, in the above embodiment, the auxiliary nut 4 of the sliding contact mechanism was used, but in FIG. 5, the auxiliary nut 2 of the rolling contact mechanism was used.
The configuration uses 2. This auxiliary nut 22 is
A rolling element 23 is provided to roll into contact with the thread of the screw 1, and the rolling element 23 is held by a fixture 25 via a spring 24.

According to the above configuration, since the auxiliary nut 22 follows the nut 2 by rolling contact, the amount of wear is smaller than that of the auxiliary nut 4 of sliding contact shown in FIG. 2, and the amount of wear of the nut 2 to be detected can be detected with high accuracy. becomes detectable.

The present invention may be modified and implemented as follows.

(2) As a connecting member, a long hole is formed in the auxiliary nuts 4 and 22, and a guide 5. is formed in the nut 2 or nut receiver 4. A configuration in which a set screw 6 and a microswitch 7 are provided may also be used.

(2) As the distance detection means, a dial gauge, an optical sensor, or the like may be used instead of the microswitch 7.

■ Auxiliary nut4. Guide 5. Set screw 6. The microswitch 7, mounting metal fittings 8, and screws 9 may be provided at both ends of the nut 2 to detect wear of the nut 2 of the lead screw mechanism that receives loads from two directions.

In addition, the present invention can be modified and implemented in various ways without departing from the spirit thereof.

〔Effect of the invention〕

As described above in detail, the present invention provides a lead screw mechanism in which a nut provided as a moving object is screwed onto a lead screw, and the rotational movement of the lead screw is converted into linear movement of the nut. an auxiliary nut that is screwed onto the lead screw at a predetermined distance from the nut; a connecting member that connects the auxiliary nut and the nut so that the auxiliary nut follows the nut; Since the present invention is equipped with a detection means for detecting a change in the above-mentioned separation distance, the amount of wear on the threads of the above-mentioned nut can be detected at all times, and a lead screw mechanism that does not cause problems such as falling off of the threads can be provided. be.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the lead screw mechanism according to the present invention, Figs. 2(a) and 2(b) show details of the same embodiment, and Fig. 2(a) is a front view; Figure (b) is the second
Figure 3 is a view seen in the H direction of Figure (a), Figure 3 is a view seen in the A-A direction of Figure 2 (a) showing the relationship between the elongated hole and the guide in the same embodiment, and Figure 4 is the same view. Electrical circuit diagram in the example, No. 5
The figures are block diagrams showing other embodiments of the present invention, and Figs.
The figure is a diagram for explaining a conventional example. 1... Lead screw (screw), 2... Nut, 3... Nut holder, 4, 22... Auxiliary nut, 5... Guide, 6... Set screw, 7... Micro switch, 23... rolling element, 24... spring, 25... fixture. Applicant's representative Patent attorney Takehiko Suzue (a) Figure 2￥&4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (3)

[Claims] (1) In a lead screw mechanism in which a nut provided with a moving target is screwed onto a lead screw and converts rotational motion of the lead screw into linear motion of the nut, the lead screw is spaced apart from the nut by a predetermined distance. an auxiliary nut that is screwed together with the auxiliary nut; a connecting member that connects the auxiliary nut and the nut so that the auxiliary nut follows the nut; and a detection means that detects a change in the separation distance; A lead screw mechanism characterized by comprising. (2) The lead screw mechanism according to claim (1), wherein the auxiliary nut is screwed onto the lead screw by a sliding contact mechanism. (3) The lead screw mechanism according to claim (1), wherein the auxiliary nut is screwed onto the lead screw by a rolling contact mechanism.