CN115889889A - circular saw - Google Patents

Abstract

A circular saw including a housing, a driving unit accommodated in the housing, a saw blade driven to rotate to cut a work piece, a speed reduction mechanism installed between the driving unit and the saw blade for changing a rotation speed of the saw blade, and a blade guard; the housing includes a gear box at least partially housing the reduction mechanism, the gear box being provided with at least one vent. According to the circular saw of the present invention, it is possible to effectively suppress the expansion of air in the gear case and to prevent the seizure of the blade guard due to the leakage of the lubricant enclosed in the gear case, thereby improving the safety, quality and durability of the circular saw.

Description

circular saw

technical field

The present invention relates to a power tool, in particular to a circular saw.

Background technique

A circular saw is a widely used power tool for cutting workpieces such as wood, metal and many other materials.

A circular saw generally includes a drive unit disposed within a housing, connected to a gear shaft of the drive unit, and the saw blade is mounted on the gear shaft. The drive unit, eg a motor, comprises a drive shaft which meshes with a gear shaft in the gear box of the circular saw. The gear meshing mechanism here is a deceleration mechanism for changing the rotation speed of the saw blade. When the motor starts to run, the drive shaft drives the gear shaft to rotate, and the saw blade is driven to rotate with the gear shaft, thereby realizing the cutting of the workpiece. Circular saws also typically include a handle disposed on the housing and a support plate that contacts the workpiece during cutting operations, as well as an upper guard and a rotatable blade guard. The rotatable saw blade guard can rotate around the rotation axis of the saw blade between its closed position and its working position. During the cutting process of the saw blade, it can prevent the rear side of the high-speed rotating saw blade from accidentally contacting the user, and at the same time It also protects the user from flying chips separated from the workpiece during the cutting process.

Usually, a certain amount of lubricant needs to be added to the gearbox to lubricate the gears during the gear meshing process. The lubricant used is generally soft, thick, grease-like semi-solid grease, therefore, the gearbox needs to have good sealing performance to prevent the grease from leaking out of the gearbox. In order to achieve high sealing performance, various sealing components are available, such as O-rings, oil seals, contact seal bearings, etc.

However, during the working process of the circular saw, the reduction mechanism in the gear box will generate heat due to high-speed rotation, which will cause the temperature inside the sealed gear box to increase, causing the air in the gear box to expand. In this case, it is necessary to set up a vent hole so that the high temperature air in the gearbox can be discharged. Simultaneously, the lubricating grease in the gear box is generally evenly distributed in the gear box when the circular saw is working, and there is also the possibility of leaking from the vent hole. Moreover, the semi-solid lubricating grease may be partially liquefied under the action of high-temperature and high-pressure gas, and then may leak from the vent hole. Grease leaking from the gearbox cools and collects in the gap between the bearing cap of the gear shaft and the mounting ring of the blade guard. Since a small amount of dust or flying chips will also fall into the gap when the saw blade is cutting the workpiece, solid grease mixed with dust or flying chips will affect the normal rebound or bias of the saw blade guard to the closed position, resulting in safety Hidden danger.

Contents of the invention

The object of the present invention is to provide a circular saw, which can effectively suppress the air expansion in the gear box and prevent the saw blade guard from being locked due to the leakage of the lubricant packaged in the gear box, thereby improving the safety and security of the circular saw. quality and durability.

A circular saw comprising a housing, a drive unit housed in the housing, a saw blade driven to rotate to cut a workpiece, installed between the drive unit and the saw blade for changing the A reduction mechanism for the rotation speed of the saw blade, and a saw blade guard; the casing includes at least a part of a gear box for accommodating the speed reduction mechanism, and the gear box is provided with at least one air hole. The gear box is provided with a vent hole to discharge the high temperature and high pressure gas caused by the operation of the reduction mechanism during the working process of the circular saw.

According to an embodiment of the present invention, the drive unit includes a motor with a drive shaft, the reduction mechanism includes a gear shaft that defines the rotation axis of the saw blade, and the gear shaft is configured such that one end of the gear shaft is engaged by a gear The input end connected with the drive shaft of the motor in a manner, the other end is the output end supporting the saw blade, the side of the gear box facing the drive unit has a bearing seat for accommodating the drive shaft, The side facing the saw blade has a recess for accommodating the input end of the gear shaft, the bearing seat and the recess are at least partially connected, the saw blade guard is installed on the output end of the gear shaft, And can rotate about the rotation axis of said saw blade between its working position and closed position.

According to a preferred embodiment of the present invention, the recess includes a side peripheral surface substantially parallel to the rotation axis of the saw blade and a bottom surface substantially perpendicular to the rotation axis of the saw blade, and the vent hole is located in the recess on the bottom surface. In this way, when the semi-solid lubricating grease sealed in the gearbox in advance leaks a small amount from the vent hole, the lubricating grease is from the inside of the gearbox (the side facing the gear shaft, the saw blade and the saw blade guard) It is discharged to the outside of the gearbox through the vent hole (that is, the side facing away from the gear shaft, saw blade and saw blade guard), so there is no gap due to the mixture of grease and dust flying debris accumulating on the saw blade guard and bearing cover The stagnation caused between them ensures that the blade guard can rotate normally between the working position and the closed position.

Preferably, the bottom surface of the recess is approximately circular, and the center of the bottom surface coincides with the rotation axis of the saw blade. The ventilation holes are positioned on the bottom surface higher than a horizontal plane extending along the rotational axis of the saw blade. When the circular saw is not working, the grease in the gear box is more likely to be concentrated in the lower half of the gear box. Therefore, the vent hole is arranged at a height exceeding the center of the bottom surface, which helps to prevent the grease from leaking from the gear box.

According to another preferred embodiment of the present invention, the input end of the gear shaft has a transmission gear and a journal, the side peripheral surface of the recess generally surrounds the transmission gear, and the bottom surface of the recess is provided at its center. There is a bearing hole supporting the journal, and the distance from the vent hole to the center of the bottom surface is smaller than the radius of the dedendum circle of the transmission gear. The ventilation holes are located under the transmission teeth, which is also beneficial to prevent excessive leakage of lubricating grease.

According to another preferred embodiment of the present invention, the included angle between the radius extending through the ventilation hole and the vertical direction on the bottom surface is smaller than the included angle between the radius extending through the center line of the drive shaft and the vertical direction . That is to say, the position of the ventilation hole is arranged in the upper half of the bottom surface close to the vertical fan-shaped area passing through the center of the bottom surface, so that the air with high pressure and high temperature can be effectively discharged, and at the same time, grease can be prevented from coming out of the bottom surface. A large number or even all of the vent holes leak out of the gear box to ensure that a sufficient amount of grease remains in the gear box, and the reduction mechanism is always fully lubricated within the service life of the circular saw.

The end of the drive shaft has a drive gear, and a bearing is sleeved on the drive shaft, and the bearing seat includes a hole for supporting the bearing and at least partly coincides with the recess in the axial direction for accommodating the In the cavity of the driving gear, several reinforcing ribs are arranged on the outer periphery of the hole, and the position of the air vent avoids the reinforcing ribs. In this way, the processing technology of the air hole is simple and convenient, and at the same time, the effect of ventilation and exhaust is better.

More preferably, the air hole is arranged obliquely on the bottom surface, and the end of the air hole facing the gear shaft is closer to the center of the bottom surface than the other end facing away from the gear shaft. Slanted vent holes provide a longer exhaust path. The vent holes are inclined radially outward from the side close to the bearing hole to the side close to the transmission teeth, so that semi-solid or partially liquefied lubricating grease is less likely to leak from the gearbox to the outside of the gearbox.

According to yet another preferred embodiment of the present invention, the vent hole is a through hole with a diameter not greater than 2mm. The ventilation hole should be as small as possible, but considering the convenience and cost of machining, a circular hole with a diameter not greater than 2mm is preferred.

Description of drawings

The embodiments can be better understood from the following detailed description when read with the accompanying drawings. It is emphasized that the various features are not necessarily drawn to scale. In fact, the dimensions may be arbitrarily increased or decreased for clarity of discussion. In the figures, the same reference numerals refer to the same elements.

Fig. 1 shows a partial schematic diagram of a circular saw according to an embodiment of the present invention;

Fig. 2 is a partial perspective view of the circular saw of one embodiment of the present invention shown in Fig. 1;

Fig. 3 is a cross-sectional view of an exemplary drive unit and reduction mechanism of the circular saw of the present invention arranged in the gear box;

Fig. 4 shows a schematic view of one side of the gear box facing the saw blade of an exemplary gear box of the circular saw of the present invention;

Fig. 5 is a partially enlarged schematic diagram at C of the gearbox shown in Fig. 3;

Fig. 6 is a schematic diagram of a side of the gearbox shown in Fig. 3 facing the drive unit;

Fig. 7 is a partially enlarged schematic view at B of the gearbox shown in Fig. 5 .

Detailed ways

Next, a circular saw according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7 . The present invention relates to circular saws for use in forming openings in workpieces and are widely used for cutting workpieces such as wood, vinyl siding and many other materials, including metal pieces. The "circular saw" in the present invention can be a circular saw used for woodworking, metalworking, ceramic processing, and/or plastic processing by rotating saw blades to cut workpieces, portable circular saws or desktop circular saws, etc. Included in what is referred to herein as a "circular saw". In addition, the "circular saw" also includes cutting saws, band saws, cutting wheels, diamond grinding wheels, and the like. In addition, the "power source" of the power tool in the present invention is typically an electric motor, and also includes an air motor, an engine, and the like.

According to an exemplary embodiment of the present invention, as shown in FIGS. The saw blade 12 of the workpiece, the deceleration mechanism 13, the upper cover 14, and the saw blade guard 15 installed between the drive unit and the saw blade for changing the rotating speed of the saw blade, the shell Body 10 also includes a gearbox 16 at least partially housing said reduction mechanism 13 .

Housing 10 may be formed from metal or plastic, making housing 10 very strong and lightweight. In one embodiment of the present invention, the upper cover 14 is supported by the housing 10 and fixed in place relative to the housing 10 , the upper cover 14 substantially covers the upper half of the saw blade 12 .

Referring to Fig. 2 and Fig. 3, according to an embodiment of the present invention, the drive unit 11 can be powered by a battery (not shown), of course, it can also be powered by a wired power supply known in the art. The driving unit 11 includes a driving motor 18 , a driving shaft 19 , and a driving bearing 20 . The driving bearing 20 is sheathed on the driving shaft 19 . The driving shaft 19 has a driving gear 21 at its end.

According to one embodiment of the present invention, the reduction mechanism 13 is configured to reduce the output rotational speed of the motor 18 to a speed suitable for rotating the saw blade 12 . According to an exemplary embodiment of the present invention, the reduction mechanism includes a gear shaft 22, and one end of the gear shaft 22 is an input end 23 connected with the drive shaft 19 of the motor through gear engagement. The end 23 has a transmission gear 24 and a journal 32 extending axially outwards, and the other end is an output end 25 supporting the saw blade 12 . The gear shaft defines the axis of rotation 17 of the saw blade, ie the center of rotation of the output end of the gear shaft coincides with the axis of rotation 17 of the saw blade. When the motor 18 is activated, the drive shaft 19 drives the transmission gear 24 of the gear shaft 22 to rotate through the drive gear 21 , and the saw blade 12 rotates around the rotation axis 17 along with the gear shaft 22 . In an alternative embodiment, the reduction mechanism may include multiple sets of gear meshing transmission mechanisms. In other exemplary embodiments, the reduction mechanism may also include a worm drive (not shown) for driving the gear shaft.

2 to 7, the housing 10 also includes a gear box 16, the gear box 16 is roughly located on the back of the upper cover 14 (right side surface in Figures 2 and 3), preferably, the gear box 16 and the upper cover 14 is integrally formed. According to an exemplary embodiment of the present invention, the gear box 16 is a cavity extending outward from the bottom center of the back of the upper cover, and several reinforcing ribs may be provided in the cavity. The gear case 16 has a bearing seat 26 for accommodating the drive shaft on the side facing the drive unit 11, and a recess 27 for accommodating the input end 23 of the gear shaft on the side facing the saw blade. The bearing seat 26 communicates with the recess 27 at least partially. Preferably, the bearing housing 26 includes a hole 33 for supporting the bearing and a cavity 34 at least partially coincident with the recess for accommodating the drive gear of the drive shaft. In this way, the driving gear 21 of the driving shaft 19 is connected with the transmission gear 24 of the input end 23 of the gear shaft 22 in a gear meshing manner in the overlapping area of the cavity 34 and the recess 27 .

The saw blade guard 15 is pivotally mounted on the bearing cover of the output end 25 of the gear shaft 22 through a mounting ring. The saw blade 12 is fixedly mounted on the output end 25 of the gear shaft through the mounting flange, the clamping flange and the clamping screw. The saw blade guard 15 substantially covers the lower half circumference of the saw blade 12 , and the saw blade guard 15 is configured to be rotatable about the rotational axis 17 of the saw blade 12 between a closed position and a working position. The circular saw 1 also includes a biasing member (not shown), such as a torsionally resilient element, configured to bias the blade guard 15 toward the closed position. That is to say, both the saw blade 12 and the saw blade guard 15 are mounted on the inside of the gear box, that is, the left side in Fig. 2 and Fig. 3, and the drive unit 11 is located on the outside of the gear box, This is the right side in Figures 2 and 3.

According to a preferred embodiment of the present invention, referring to FIGS. 2 to 5 , the recess 27 includes a side peripheral surface 28 substantially parallel to the rotation axis 17 of the saw blade and a bottom surface perpendicular to the rotation axis 17 of the saw blade. 29 , at least one ventilation hole 30 is disposed on the bottom surface 29 . In this way, the grease previously packaged in the gear box for lubrication can be partially discharged from the gear box (left side in Fig. 3) to the outside of the gear box (right side in Fig. side), that is, the side facing away from the gear shaft, saw blade and saw blade guard. Therefore, there is no stagnation caused by the mixture of grease and dust flying debris accumulating between the gap between the saw blade guard 15 and the gear shaft bearing cover, ensuring that the saw blade guard 15 can be normally in the working position and the closed position rotate between.

Preferably, the bottom surface 29 of the recess is approximately circular, the center of the bottom surface coincides with the rotation axis of the saw blade, and the side peripheral surface 28 and the bottom surface 29 form a cylindrical recess. The side peripheral surface 28 of the recess substantially surrounds the transmission gear 24, and the bottom surface 29 of the recess is provided at its center with a bearing hole 31 supporting a journal 32 of the gear shaft. The journal 32 of the gear shaft 22 is supported in the bearing bore 31 via a bearing, and the position of the vent hole 30 on the bottom surface is at least above the level passing through the axis of rotation 17 of the saw blade, here, The axis of rotation 17 of the saw blade coincides with the center line of the bearing hole 31 . That is to say, the position of the ventilation hole 30 on the bottom surface 29 should be located in the upper half of the bottom surface, at least higher than the horizontal plane at the center of the bottom surface. More preferably, the angle between the extension line passing through the vent hole 30 and the center of the bottom surface and the vertical direction is smaller than the angle between the extension line passing through the center of the bearing seat hole 26 and the center of the bottom surface and the vertical direction. angle. That is to say, the position of the air hole 30 is set in the upper half of the bottom surface close to the fan-shaped area passing through the center of the bottom surface in the vertical direction. Since the lubricating grease needs to be added into the gearbox in advance to lubricate the transmission of the drive shaft and the gear shaft. The filled grease needs to be applied in a sufficient amount according to the service life of the circular saw, so as to ensure good lubrication of the circular saw throughout its life cycle. However, as mentioned above, semi-solid grease will liquefy in a small amount under high-temperature and high-pressure air, and the fluidity of the liquefied lubricant will increase significantly, and it may be discharged from the gearbox through the vent hole, so the vent hole is set on the bearing. The upper part of the hole can effectively discharge high-pressure and high-temperature air, and at the same time prevent a large amount or even all of the grease from leaking out of the gear box, so as to ensure that a sufficient amount of grease remains in the gear box. Always adequately lubricate the reduction mechanism throughout its service life.

Referring to FIG. 6 and FIG. 7 , according to yet another preferred embodiment of the present invention, several reinforcing ribs 35 are provided on the outer periphery of the hole portion 33 , and the position of the vent hole 30 avoids the positions of the radial reinforcing ribs 35 . In this way, the processing technology of the air hole is simple and convenient, and at the same time, the effect of ventilation and exhaust is better. The reinforcing ribs can be used for connecting an air guiding device 36 . Since the vent hole is located in the area surrounded by the reinforcing ribs, a small amount of grease leaking from the vent hole will be accommodated by the air guiding device and will not accumulate on the gear shaft or the driving unit.

Preferably, the air hole 30 is a circular hole with a diameter not greater than 2mm. The ventilation hole should be as small as possible, but considering the convenience and cost of machining, a round hole with a diameter of no more than 2mm is easy to process, and at the same time can ensure a good exhaust effect, and will not cause excessive grease from Gearbox leaks. In fact, the leakage of grease from the vent hole usually only occurs at the beginning of the circular saw being put into use, and the amount of grease initially packed in the gear box is relatively high. After a period of use, the gear mesh of the reduction mechanism has been completely worn in, and the stock of grease in the gearbox has gradually reached a balance value, which can ensure the sufficient lubrication of the reduction mechanism and will not continue to leak more from the vent hole .

More preferably, the vent hole 30 is an oblique vent hole, and the vent hole is not perpendicular to the bottom surface 29 of the gear case. Slanted vent holes provide a longer exhaust path. Preferably, the vent hole is inclined radially outward from the side close to the bearing hole 31 to the side close to the transmission gear 24, so that the lubricating grease in the liquefied state is less likely to leak from the gearbox to the gearbox In addition, it ensures that the lubricating grease encapsulated in the gearbox can always maintain sufficient lubrication for the drive unit and the reduction mechanism, prolonging the service life of the tool.

As mentioned above, although the exemplary embodiments of the present invention have been described in the description with reference to the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments, and there can be many other embodiments, and the scope of the present invention should be determined by the right Requirements and their equivalent meanings.

Claims (10)

1. A circular saw including a housing, a driving unit accommodated in the housing, a saw blade driven to rotate to cut a work piece, a speed reduction mechanism installed between the driving unit and the saw blade for changing a rotation speed of the saw blade, and a blade guard; the housing includes a gear box at least partially housing the reduction mechanism, wherein the gear box is provided with at least one vent.

2. The circular saw of claim 1, wherein the drive unit includes a motor having a drive shaft, the speed reduction mechanism includes a gear shaft defining an axis of rotation of the saw blade, the gear shaft is configured with an input end coupled to the drive shaft of the motor in gear engagement at one end and an output end supporting the saw blade at the other end, the gear housing has a bearing seat receiving the drive shaft on a side facing the drive unit and a recess receiving the input end of the gear shaft on a side facing the saw blade, the bearing seat and recess being in at least partial communication, the blade guard being mounted to the output end of the gear shaft and rotatable about the axis of rotation of the saw blade between its operative and closed positions.

3. The circular saw of claim 2, wherein the pocket includes a side peripheral surface substantially parallel to the rotational axis of the saw blade and a bottom surface substantially perpendicular to the rotational axis of the saw blade, the vent hole being located on the bottom surface of the pocket.

4. The circular saw of claim 3, wherein the pocket has a generally circular bottom surface, a center of the bottom surface coinciding with the rotational axis of the saw blade.

5. The circular saw of claim 4, wherein the vent hole is located higher on the bottom surface than a horizontal plane extending along a center of the bottom surface.

6. The circular saw of claim 5, wherein the input end of the gear shaft has a transmission gear, and the distance from the vent hole to the center of the bottom surface is smaller than the radius of a root circle of the transmission gear.

7. The circular saw of claim 6, wherein a radius extending through the vent hole on the bottom surface is at a smaller angle to vertical than a radius extending through a centerline of the drive shaft.

8. The circular saw of any one of claims 2 to 7, wherein the drive shaft has a drive gear at a distal end thereof, a bearing is fitted on the drive shaft, the bearing holder includes a hole portion for supporting the bearing and a cavity portion axially coinciding at least in part with the recess for receiving the drive gear, the hole portion has a plurality of reinforcing ribs at an outer periphery thereof, and the vent hole is located so as to avoid the reinforcing ribs.

9. The circular saw of any one of claims 3 to 7, wherein the air vent is obliquely provided on the bottom surface, and one end of the air vent facing the gear shaft is closer to the center of the bottom surface than the other end thereof facing away from the gear shaft.

10. The circular saw of any one of claims 1 to 9, wherein the vent hole is a circular hole having a diameter of no more than 2 mm.

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