ANGLE GRINDER GEARBOX

Abstract

This utility model relates to the design elements of electric hand tools with a rotating working element and can be used in angle grinders to transmit torque from an electric motor to the working tool while reducing the rotational speed and changing the direction of the rotational axis. The gearbox comprises a housing, an input shaft, and an output spindle configured to mount the working tool. The gearbox is designed as a two-stage gearbox, comprising a first stage in the form of a bevel gear pair and a second stage in the form of a cylindrical gear pair. The driven wheel of the bevel gear pair and the driving wheel of the cylindrical gear pair are mounted on an intermediate shaft. The driven wheel of the cylindrical gear pair is connected to the output spindle. The driving wheel of the bevel gear pair is mounted on the electric motor shaft. The intermediate shaft is mounted in the housing and can rotate in supports.The driven wheel of the cylindrical gear pair is rigidly connected to the output spindle. This increases the gear ratio of the angle grinder gearbox. 3 spare parts, 1 fig.

Description

[0001] The device belongs to the structural elements of electric hand tools with a rotating working element and can be used in angle grinders to transmit torque from the electric motor to the working tool with a decrease in the rotation speed and a change in the direction of the rotation axis.

[0002] Angle grinders are equipped with electric motors whose shaft speeds significantly exceed the permissible operating speeds for most abrasive, cutting, and polishing tools. The use of a gearbox in the angle grinder design is necessary to reduce the output spindle speed to safe and efficient operating values, as well as to change the direction of the rotation axis, ensuring ergonomics and operator comfort. Dynamically, the gearbox multiplies the torque on the output shaft, which is necessary to overcome material resistance during cutting or grinding operations. This transformation of motion parameters ensures sufficient traction and force characteristics on the working element, preventing the drive from stalling under load and maintaining a stable machining mode.

[0003] The closest in technical essence is the gearbox known from the invention patent RU No. 2441740 "ELECTRIC HAND-HELD ANGLE GRINDING MACHINE", dated 13.12.2010, published 10.02.2012, IPC B24B 23 / 02. The gearbox housing is made of fixed and moving parts. The moving part contains a bevel gear, a bearing, and a gearbox shaft, on which a cutting wheel is fixed. The fixed part of the housing contains an axle inserted into the gearbox, a locking hole, and a block of two bevel satellite gears inserted into the gearbox. The movable part of the gearbox housing is secured to the fixed part by means of an axis with the ability to rotate around it until the bevel gear engages with the bevel gear-satellite and is fixed in this position by means of a locking device inserted into the movable part, which is designed with the ability to be placed in the locking hole.The gearbox housing at the point where the gearbox shaft exits is equipped with a removable angular cover with a damper.

[0004] The kinematic design of a prior art gearbox is implemented as a single-stage bevel gear. This design feature limits the maximum gear ratio achievable within a single stage without critically increasing the driven wheel diameter, which is determined by the housing's spatial and dimensional constraints. This limitation directly determines the required drive power characteristics: to implement a single-stage design and provide the required torque at the output link with a limited gear ratio, the electric motor must have increased power. This kinematic dependence reduces the variability of design solutions and hinders the effective coupling of the gearbox with modern compact high-speed electric motors.

[0005] The objective of the claimed technical solution is to create a gearbox for an angle grinder that ensures coupling with a high-speed electric motor without losing the required power characteristics on the output shaft.

[0006] The stated problem is solved by means of an angle grinder gearbox comprising a housing, an input shaft, and an output spindle configured to mount a working tool, wherein the gearbox is made two-stage and comprises a first stage in the form of a bevel gear pair and a second stage in the form of a cylindrical gear pair, wherein the driven wheel of the bevel gear pair and the driving wheel of the cylindrical gear pair are mounted on an intermediate shaft; the driven wheel of the cylindrical gear pair is connected to the output spindle; the driving wheel of the bevel gear pair is mounted on the shaft of an electric motor; the intermediate shaft is mounted in the housing with the ability to rotate in supports; the driven wheel of the cylindrical gear pair is rigidly connected to the output spindle.

[0007] The essence of the technical solution is illustrated by the drawing, where Fig. 1 shows the gearbox of an angle grinder.

[0008] Fig. 1 shows: gearbox 1 of an angle grinder, intermediate shaft 2, output spindle 3, drive wheel 4 of a bevel gear pair, driven wheel 5 of a bevel gear pair, drive wheel 6 of a cylindrical gear pair, driven wheel 7 of a cylindrical gear pair.

[0009] The gearbox of the angle grinder is designed as follows.

[0010] The gearbox 1 of the angle grinder is designed to transmit torque from the input shaft of the electric motor to the spindle 3 with a reduction in the rotational speed and a change in the position of the rotational axis by 90 degrees. The gearbox 1 of the angle grinder comprises a housing, inside which two stages of rotational speed reduction are located, while the output spindle 3 is located on the outer side of the housing, configured to mount a working tool. The working tool can be cutting wheels, grinding wheels, cleaning wheels, flap wheels, wire brushes or polishing discs. The ability to mount the working tool can be ensured by any method known in the prior art, for example, due to a threaded connection, an eccentric clamp, a quick-release nut or a flange mount with centering. The drive wheel 4 of the bevel gear pair is located in the housing of the gearbox 1.Optionally, drive wheel 4 is mounted on the electric motor shaft. Wheel 4 may be mounted on the electric motor shaft by any method known in the art, such as a splined connection, a keyed connection, a press fit, or using a bevel shaft with a locking nut. Drive wheel 4, together with driven wheel 5, form the first stage of gearbox 1 in the form of a bevel gear pair. The first stage of gearbox 1 is designed for the initial reduction of rotational speed and the change in rotational direction. The number of teeth on drive wheel 4 is fewer than on driven wheel 5, which ensures the initial reduction in speed. The design of the pair as a bevel gear transmission ensures a change in the direction of rotation, so that intermediate shaft 2 rotates perpendicular to the axis of rotation of the electric motor shaft.The driven wheel 5 of the bevel gear pair is mounted on the intermediate shaft 2 by any method known in the art, for example, by means of a keyed connection, a splined connection, or a press fit with additional fixation by a retaining ring or nut. Optionally, the intermediate shaft 2 is mounted in the gearbox 1 housing with the ability to rotate in supports. In a particular implementation case, the supports can be implemented in the form of radial or radial-thrust ball bearings installed in the seats of the gearbox 1 housing. The driving wheel 6 of the cylindrical gear pair is mounted on the intermediate shaft 2. The wheel 6 is mounted on the shaft 2 by any method known in the art, for example, by means of a keyed connection, a splined connection, a press fit, or by manufacturing the driving wheel 6 and the intermediate shaft 2 as a single part. The driving wheel 6 and the driven wheel 7 form the second stage of the gearbox 1 in the form of a cylindrical gear pair.The second stage is designed to further, secondary reduce the rotational speed. The number of teeth on the drive gear 6 is smaller than on the driven gear 7, ensuring a further reduction in speed and a proportional increase in torque on the output spindle 3 to the required operating values. Driven gear 7 of the cylindrical gear pair is rigidly connected to the output spindle 3, for example, by mounting them on a single shaft and rigidly connecting them via a keyed connection, a splined connection, a press fit, or by being manufactured as a single piece.

[0011] The angle grinder gearbox is used as follows.

[0012] A working tool, such as a cutting or grinding wheel, is mounted on the output spindle 3. The tool is mounted using, for example, a clamping flange and a locking nut screwed onto the threaded portion of spindle 3. The angle grinder is connected to a power source, such as a household electrical network. By pressing the corresponding start button, the electrical circuit is closed, causing the rotor of the electric motor to rotate. The rotation of the electric motor shaft is transmitted via the drive wheel 4 to the gearbox 1. The first stage of gearbox 1 provides an initial reduction in the rotational speed and a change in the direction of the rotation axis by 90 degrees, transmitting torque to intermediate shaft 2. The second stage of gearbox 1 provides an additional reduction in the rotational speed and a corresponding increase in torque, transmitting it from intermediate shaft 2 to driven wheel 7 and then to the output spindle 3.Thus, the output spindle 3 rotates at the required operating frequency, while the working element is supplied with a torque sufficient to stably overcome the resistance forces of the material being processed without reducing productivity and the risk of the engine stopping under load.

[0013] The two-stage design of gearbox 1, with a sequential arrangement of bevel and cylindrical gear pairs, ensures a high overall gear ratio, sufficient not only to reduce the speed of output spindle 3 to the required operating value but also to proportionally multiply the torque required to steadily overcome the resistance forces of the workpiece. The first bevel stage optimally addresses the problem of changing the direction of the rotation axis and the initial reduction in speed, while the second cylindrical stage achieves a high gear ratio without critically increasing the dimensions of driven wheel 7. This design allows the use of modern, high-speed, compact electric motors in angle grinders, while maintaining the required performance characteristics and service life of the tool, as well as ensuring its reliability.As an alternative to known gearboxes, the claimed device expands the arsenal of means designed to reduce the speed of the output spindle of angle grinders while simultaneously changing the direction of the rotation axis.

[0014] The technical result of the claimed technical solution is to increase the gear ratio of the angle grinder gearbox. The technical result is achieved by means of an angle grinder gearbox comprising a housing, an input shaft, and an output spindle configured to mount a working tool, wherein the gearbox is made two-stage and comprises a first stage in the form of a bevel gear pair and a second stage in the form of a cylindrical gear pair, wherein the driven wheel of the bevel gear pair and the driving wheel of the cylindrical gear pair are mounted on an intermediate shaft; the driven wheel of the cylindrical gear pair is connected to the output spindle; the driving wheel of the bevel gear pair is mounted on the shaft of the electric motor; the intermediate shaft is mounted in the housing with the possibility of rotation in supports; the driven wheel of the cylindrical gear pair is rigidly connected to the output spindle.

Claims

1. A gearbox for an angle grinder, comprising a housing, an input shaft and an output spindle, configured to accommodate a working tool, characterized in that it is made two-stage and comprises a first stage in the form of a bevel gear pair and a second stage in the form of a cylindrical gear pair, wherein the driven wheel of the bevel gear pair and the driving wheel of the cylindrical gear pair are mounted on an intermediate shaft, and the driven wheel of the cylindrical gear pair is connected to the output spindle.

2. A gear reducer according to paragraph 1, characterized in that the drive wheel of the bevel gear pair is mounted on the shaft of the electric motor.

3. A gearbox according to paragraph 1, characterized in that the intermediate shaft is installed in the housing with the possibility of rotation in the supports.

4. A gear reducer according to paragraph 1, characterized in that the driven wheel of the cylindrical gear pair is rigidly connected to the output spindle.

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