JPH06190740A - Screw driving machine - Google Patents

Abstract

PURPOSE:To make screw fitting and removal with the required time shortened, which is free from intense noise generation, by performing screw driving and unscrewing with the first system at a high speed and with low torque while conducting the tightening and loosening with the second system at a very low speed with high torque. CONSTITUTION:A screw fastening machine is equipped with a frictional continuous transmission 2, whose speed change range includes the point where the rotating speed of the output shaft 4 nullifies, and one or more planetary gearing mechanisms 16 to drive a sun gear 12 together with the transmission 2, wherein the arrangement is equipped with the first system to transmit the rotation of the sun gear 12 to a driver shaft 11 and the second system to transmit the rotation of a carrier 14 to the driver shaft 11. Screw driving and unscrewing are performed by the first system at a high speed with low torque, and tightening and loosening are conducted at a very low speed with high torque by the second system while the torque vs. rotating speed characteristic of the transmission 2, at the time the output shaft 4 rotating speed is approached to zero, is utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a diameter of 20 mm to 40 mm.
As described above, the present invention relates to a screw tightening machine that is preferably used for attaching and detaching a relatively large screw.

[0002]

2. Description of the Related Art Most screw tighteners currently on the market are so-called impact wrenches that utilize compressed air.
This is relatively lightweight and has good workability, but it has a major drawback that it produces a violent impact sound. As a screw tightener that does not generate noise like an impact wrench, an electric motor driven type or a hydraulic driven type is also known, but they have an extremely large drawback that the time required for screwing is too long. Yes, it is difficult to work efficiently.

On the other hand, the applicant of the present application first developed a friction continuously variable transmission of utility model registration No. 1806717 described in Japanese Utility Model Publication No. 1-29944, which can be used for a screw tightener. In this friction continuously variable transmission, a transmission system from an input shaft to an output shaft is configured to include a plurality of conical rotors that perform planetary motion, and frictionally engages conical surfaces of the plurality of conical rotors in common. A non-rotational speed change ring is provided, and a transmission surface having a concave cross section that frictionally engages with a transmission wheel on the input shaft and a flat transmission surface that frictionally engages with the transmission wheel on the output shaft are provided on the conical rotor. Of the type provided in (1), a plurality of spring rods, one end of which is supported by the casing of the transmission, are provided, and the other ends of the plurality of spring rods are engaged with the transmission ring.

The friction continuously variable transmission has a large torque that can be generated when the rotation speed of the output shaft is 0 or when the rotation speed of the output shaft is 0. Therefore, this point is utilized to construct a screw tightener. However, the screw tightener that uses this friction continuously variable transmission can be applied only to small screws with a diameter of 5 mm or less, and for large-diameter screws, the structural It cannot be applied because of the relationship.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances of the conventional screw tightening machine, that is, the condition that the operation is quiet, the condition that the operation speed is high, and the condition that the screw diameter is relatively large. It is an issue to be solved to develop a screw tightener that satisfies the condition that it can be applied to screws.

[0006]

SUMMARY OF THE INVENTION A screw tightener according to the present invention has a spring which exerts a force for moving a transmission ring toward a high speed side, and a transmission ring which is directed toward a low speed side as the load torque increases. And a cam mechanism that exerts a force to move the sun gear by the friction continuously variable transmission including a point where the rotational speed of the output shaft is set to 0 in the speed change range, and a sun gear by the friction continuously variable transmission. A first system for transmitting rotation of a sun gear of the planetary gear mechanism to a driver shaft (screwdriver shaft), comprising a driven one or more stages of planetary gear mechanism,
A second system for transmitting the rotation of the carrier of the planetary gear mechanism to the driver shaft, wherein screwing and unscrewing are performed by the first system under high-speed and low-torque conditions, and screw tightening and screwing are performed. The slackening is performed under the conditions of very low speed and high torque while utilizing the "torque-rotational speed characteristic" of the friction continuously variable transmission when the rotational speed of the output shaft approaches 0 by the second system. Characterize.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The screw tightening machine according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a graph diagram for explaining the operation of the screw tightener according to the present invention, FIG. 2 is a vertical sectional view showing an example of the screw tightener according to the present invention, and FIGS. It is drawing which changes a state and shows a part.

In FIG. 2, 1 is an electric motor as a drive source, 2 is a friction continuously variable transmission driven by the electric motor 1,
Reference numerals 3 and 4 are an input shaft and an output shaft of the friction continuously variable transmission 2, respectively. The transmission system from the input shaft 3 to the output shaft 4 of the friction continuously variable transmission 2 is configured to include a plurality of conical rotors 5 that perform planetary motion. Reference numeral 6 denotes a non-rotating transmission ring, which is commonly frictionally engaged with the conical surfaces of the plurality of conical rotors 5.
The speed change ring 6 is frictionally engaged with a transmission wheel 7 on the input shaft 3 and frictionally engaged with a race ring 8 on the output shaft 4. 9 is a spring that exerts a force to move the speed change ring 6 toward the high speed side, and 10 is a speed change ring 6
This is a cam mechanism that exerts a force to move the gear toward the low speed side.

Reference numeral 11 denotes a driver shaft (screwdriver shaft). Between the driver shaft 11 and the output shaft 4 of the friction continuously variable transmission 2, "the sun gear 12, the planetary gear 13, the carrier 14 and the internal gear are also used. Planetary gear mechanism 1 including case 15
6 ”is interposed. Driving of the driver shaft 11 by the friction continuously variable transmission 2 is performed by selecting one of the following two systems.

In one of the above two systems (first system), the dog clutch 17 is "disengaged" as shown in FIG. (Under the condition), the system for rotating the driver shaft 11 at high speed via the riding cam device 19, while the other system (second system) of the above two systems is as shown in FIG. This is a system for rotating the driver shaft 11 at a very low speed in a high torque state by setting the dog clutch 17 to the "continuation" state when the device 19 is disabled. If you divide the installation of screws into "screw-in" and "screw tightening" that follows,
The first system is a system for promptly screwing in, and the second system is a system for ensuring that screwing subsequent to screwing-in occurs by applying a sufficiently large torque.

The state where the driver shaft 11 is driven by the first system is shown by a point P ₁ in FIG. In this drive state, the driver shaft 11 is driven under the condition of "high speed, low torque". The state in which the driver shaft 11 is driven by the second system is shown by the area P ₂ P ₃ in FIG. In this driving state, the driver shaft 11 is "slow speed,
It is driven under the condition of "high torque".

The riding cam device 19 comprises a riding cam 20 and a cam follower 21. The cam follower 21 is an element provided on the slidable member 23 spline-connected to the extension 22 of the sun gear 12. Also,
The dog clutch 17 is composed of a member 17A provided on the carrier 14 of the planetary gear mechanism 16 and a member 17B splined to the driver shaft 11.

Reference numeral 24 denotes a ball bearing, which is provided on one of the members 17A and 17B constituting the dog clutch 17 which is one of the members 17B. The ball bearing 24 acts as a member that transmits a force when the riding cam device 19 pushes up the slidable member 23.

To remove the screw in the tightened state, the electric motor 2 as the drive source of the friction continuously variable transmission is reversed to the state shown in FIG.
The screw loosening from the P ₃ point to the P ₂ point and the subsequent screw unscrewing at the P ₁ point may be sequentially performed.

The planetary gear mechanism 16 is a reduction mechanism. In the case of the one shown in the figure, this reduction gear mechanism is provided as a single-stage type, but if the torque required for screw tightening and loosening is large, increase the number of installed stages to increase the generated torque. You can

[0017]

As described above, the screw tightening machine according to the present invention does not generate a strong noise unlike the conventionally used impact wrench. Further, this one requires much shorter time than the conventionally known hydraulically actuated type, so that the screws can be attached and detached.

[Brief description of drawings]

FIG. 1 is a graph diagram for explaining an operation performed by a screw tightener according to the present invention.

FIG. 2 is a vertical sectional view showing an example of a screw tightener according to the present invention.

FIG. 3 is a partial view showing a part of FIG.

FIG. 4 is a partial view of FIG. 2 in a different state.

[Explanation of symbols]

1 electric motor 2 friction continuously variable transmission 3 input shaft 4 output shaft 5 conical rotor 6 speed change ring 7 transmission wheel 8 race ring 9 spring exerting force to move the speed change ring toward high speed side 10 speed change ring Cam mechanism 11 that exerts force to move toward low speed side 11 Driver shaft 12 Sun gear 13 Planetary gear 14 Carrier 15 Case 16 Planetary gear mechanism 17 Dog clutch 17A Dog clutch component 17B Dog clutch component 19 Riding cam device 20 Riding Riding cam of cam device 21 Cam follower of riding cam device 22 Sun gear extension 23 Slidable member 24 Ball bearing

Claims (1)

[Claims] 1. A spring that exerts a force to move the speed change ring toward a high speed side, and a cam mechanism that exerts a force to move the speed change ring toward a low speed side as the load torque increases. And a friction continuously variable transmission including a point in which the rotational speed of the output shaft is set to 0 in the gear shift range,
A first system for transmitting the rotation of the sun gear of the planetary gear mechanism to a driver shaft (screwdriver shaft), comprising a planetary gear mechanism of one or a plurality of stages in which the sun gear is driven by the friction continuously variable transmission, A second system for transmitting the rotation of the carrier of the planetary gear mechanism to the driver shaft, wherein screwing and unscrewing are performed by the first system under high-speed and low-torque conditions, and screw tightening and screwing are performed. The slackening is performed under the conditions of very low speed and high torque while utilizing the "torque-rotational speed characteristic" of the friction continuously variable transmission when the rotational speed of the output shaft approaches 0 by the second system. A characteristic screw tightener.