CN219617481U - Random orbit grinding tool machine - Google Patents

Abstract

A random orbit grinding machine tool is provided with a power motor, a driving shaft connected with the power motor, an eccentric block connected with the driving shaft, a tool holder arranged on the eccentric block, and a grinding disc connected with the tool holder and indirectly driven by the power motor. The random orbit grinding tool machine is provided with a friction piece arranged on the eccentric block, the friction piece contacts the grinding disc, the friction piece is provided with a first state for providing precompression for the grinding disc when the power motor is not started, a second state for displacing along with the eccentric block when the power motor is started and generating deformation according to the rotation of the grinding disc, and a third state for providing braking force for the grinding disc when the power motor is stopped.

Description

Random orbit grinding tool machine

Technical Field

The present utility model relates to a random orbital sander, and more particularly to a random orbital sander having a friction member for providing braking force to a grinding disc.

Background

The random orbit grinder (Random Orbital Sander) is characterized in that a Balancer (commonly called eccentric block) is connected with a spindle of a power motor, a Bearing seat (Bearing) is arranged on the Balancer, the Bearing seat provides a tool holder (also called Bearing) arranged therein, and the center line of the Bearing seat is parallel to but not coaxial with the center line of the spindle of the power motor, namely, an eccentric distance is arranged between the center lines. In addition, a rotating shaft (Spindle) is arranged in the center of the bearing, a grinding disc (grinding pad) of the random orbit grinding tool is connected with the rotating shaft through a locking screw, so that the center axis of the grinding disc and the center axis of the power motor are parallel and are in different coaxial states, and the Eccentric distance is arranged between the two center axes, namely the grinding disc and the power motor are in Eccentric connection (eccentrical link). Since the grinding disc is connected to the balancer via the bearing, the grinding disc is free to rotate instead of being Hard-coupled to the power shaft (Hard link).

When the power motor rotates, the motor mandrel drives the balancer to synchronously rotate, and the balancer drives the grinding disc to rotate. The abrasive disk will then undergo two different movements: the first is that the grinding disk keeps the eccentric distance from the motor spindle and rotates around the motor spindle, and this Orbital motion (Orbital motion) around the motor spindle is called "revolution" (Orbital revolution), the rotational speed being synchronized with the rotational speed of the motor spindle and the rotational speed of the balancer.

The second is that the abrasive disk rotates (revolution on its own axis) on its own spindle, known as "spin". The reason why the grinding disc rotates is that the grinding disc is eccentrically connected with the motor spindle, and the grinding disc can freely rotate on the bearing. When the polishing disk revolves around the motor spindle, the inner and outer sides of the polishing disk receive different amounts of inertial force, and the outer side is farther from the spindle than the inner side, so that the inertial force is greater, and the polishing disk rotates in the revolving direction. The rotational speed of the spinning motion is mainly affected by the eccentric distance between the abrasive disk spindle and the motor spindle. The larger the eccentric distance is, the higher the rotation speed is, and the smaller the eccentric distance is, the lower the rotation speed is.

Taking a 5mm random orbital abrading tool (eccentric size of 2.5 mm) with a 6 "abrading disc as an example, the abrading disc performs an orbital motion of 5mm diameter around the motor spindle at a position 2.5mm from the motor spindle at 10000rpm of rotational speed of the motor spindle. The abrasive disk also simultaneously underwent an eccentric spinning motion at about 5500rpm under no load. When the random orbit grinder carries out grinding operation, the friction force generated by the contact of an abrasive and the grinding disc can lead to the reduction of the rotation movement speed of the grinding disc, and the heavier the load of the power tool is, the more the rotation speed of the grinding disc is reduced. For example, the spin speed is about 300-400 rpm at light load and about 150-300 rpm at heavy load.

When the power motor stops rotating, the stored kinetic energy of the balancer when it was previously rotated drives the balancer to continue rotating for several seconds until the stored kinetic energy is consumed. At this time, the rotation movement of the polishing disk is stopped. Taking a 6' grinding disc mounted on the random orbital grinding tool with an eccentric distance of 2.5mm (orbital diameter of 5 mm) as an example, the motor stops rotating and the grinding disc continues to rotate for 9-12 seconds to stop completely. In certain situations of use, when the random track grinder is required to stop the power motor, the grinding wheel must stop rotating in a short period of time (1-3 seconds) and there is a need for a brake mechanism on the tool.

The main braking method is to set an elastic rubber ring on a fan cover (or a shell) of the random orbit grinding tool machine, one side of the elastic rubber ring is fixed on the fan cover, and the other side is pressed on the surface of the grinding disc by self elasticity. Because the fan housing is fixed and not rotated, when the power motor does not start to rotate, the grinding disc is pressed by the elastic rubber ring and is difficult to bounce. The power motor starts to rotate, and when the power motor exceeds the friction force of the elastic rubber ring pressing on the grinding disc, the grinding disc can be dragged to rotate. When the power motor stops running, the grinding disc loses the dragging force of the power motor and is influenced by the friction force generated by the compression of the elastic rubber ring, so that the rotation can be stopped in a short time. Related patents are as follows: taiwan TWM279440, taiwan TWM574093, CN2858182Y, CN108290265A, CN213136241U, CN103813884B, CN1088001C, CN206393407U, CN110594316A, US5018314, US5317838, US5384984, US5392568, US5807169, US6503133, US6527631, US7104873, US7270598, US7371150, US10046433, US2010062695, US20220126417, JP4061053B2, WO2004030864, GB2359266.

However, the elastic rubber ring is dragged and rubbed on the surface of the grinding disc for a long time, and the elastic rubber ring is quickly worn out to lose function. In addition, when the power motor runs, the elastic rubber ring is always pressed on the grinding disc, so that the load of the power motor can be increased, the rotating speed of the power motor and the revolution speed of the grinding disc can be reduced, the rotating speed of the grinding disc can be reduced, and the grinding efficiency and the grinding quality can be further affected.

In addition to the foregoing, taiwan TWM 27941 and US6110028 disclose other types of disc brakes, but the implementation thereof still has the problems.

Disclosure of Invention

The main purpose of the present utility model is to solve the problems of the braking method used in the conventional random track grinder.

In order to achieve the above object, the present utility model provides a random orbital grinding machine tool having a power motor, a drive shaft coupled to the power motor, an eccentric mass coupled to the drive shaft, a tool holder disposed on the eccentric mass, and a grinding disc coupled to the tool holder and driven indirectly by the power motor. The random orbit grinding tool machine is provided with a friction piece arranged on the eccentric block, the friction piece contacts the grinding disc, the friction piece is provided with a first state for providing precompression for the grinding disc when the power motor is not started, a second state for displacing along with the eccentric block when the power motor is started and generating deformation according to the rotation of the grinding disc, and a third state for providing braking force for the grinding disc when the power motor is stopped.

In one embodiment, the grinding disc and the driving shaft have an eccentric distance, and the end of the friction piece contacting the grinding disc has an offset range which is greater than or equal to two times of the eccentric distance.

In one embodiment, the friction member has a base, a connecting portion disposed on the base and attached to the eccentric block, and at least one flexible contact portion disposed on a side of the base facing the polishing disc.

In one embodiment, the at least one flexible contact portion is a tubular structure.

In one embodiment, a line of spatial extension within the tube of the tubular structure intersects the polishing platen.

In one embodiment, an intraductal spatial extension of the tubular structure is parallel to the polishing platen.

In one embodiment, the at least one flexible contact portion is a foot structure having a bending direction that is parallel to the rotation direction of the driving shaft.

In one embodiment, the base forms an assembly opening for assembling the eccentric block, and the assembly portion is disposed in the assembly opening.

In one embodiment, the base has a plurality of spaced apart blades on a side of the base remote from the abrasive disk.

In one embodiment, the eccentric block has a first portion connected to the driving shaft and a second portion offset from the first portion, and the connecting portion is connected to the second portion.

In one embodiment, the base is higher in level than the bottom edge of the second portion of the eccentric mass.

In one embodiment, the friction member is disposed on a wind flow generating member attached to the eccentric block.

In one embodiment, the eccentric mass has a first portion coupled to the drive shaft and a second portion offset from the first portion, the wind flow generating member being coupled to the second portion.

In one embodiment, the eccentric mass has a first portion coupled to the drive shaft and a second portion offset from the first portion, and the friction member is coupled to the second portion.

Compared with the prior art, the utility model has the following characteristics: the random orbit grinding tool machine provided by the utility model is provided with the friction piece arranged on the eccentric block, and the friction piece is deformed according to the motion of the grinding disc in the second state, and the rotation speed of the grinding disc is not excessively reduced along with the rotation of the eccentric block, so that the grinding efficiency and the grinding quality can be prevented from being greatly reduced. In the third state, the friction member provides braking force to the grinding disc, so that the grinding disc can stop rotating in a short time.

Drawings

FIG. 1 is a schematic diagram of an embodiment of the present utility model;

FIG. 2 is a schematic illustration of the abrasive path of the abrasive disk of the present utility model;

FIG. 3 is a schematic view of the eccentric mass and friction member configuration of the present utility model;

FIG. 4 is a diagram illustrating the wobble of the friction member in a first state according to the present utility model;

FIG. 5 is a schematic view of another embodiment of a friction member according to the present utility model;

FIG. 6 is a schematic partial cross-sectional view of another embodiment of a friction member according to the present utility model;

FIG. 7 is a diagram illustrating the wobble of another embodiment of the friction member in a first state according to the present utility model;

FIG. 8 is a schematic view of a friction member according to another embodiment of the present utility model;

FIG. 9 is a schematic side view of a portion of a friction member according to yet another embodiment of the present utility model;

FIG. 10 is a rocking schematic view of still another embodiment of the friction member in a first state according to the present utility model;

fig. 11 is a schematic structural diagram of another embodiment of the present utility model.

[ symbolic description ]

20: random orbit grinding tool machine

21: power motor

22: driving shaft

23: eccentric block

231: first part

232: second part

24: tool holder

25: grinding disc

26: friction piece

261: end of the device

262: base part

263: assembling part

264: flexible contact

265: foot structure

266: tubular structure

267: line of extension of space in tube

268: assembled opening

269: positioning wall

260: blade

27: mask cover

28: wind current generating piece

40: distance of eccentricity

41: offset range

50: grinding track

Detailed Description

The detailed description and the technical content of the utility model are now as follows in conjunction with the accompanying drawings:

referring to fig. 1, the present utility model provides a random orbital grinding machine tool 20, wherein the random orbital grinding machine tool 20 has a power motor 21, a drive shaft 22 connected to the power motor 21, an eccentric block 23 connected to the drive shaft 22, a tool holder 24 provided on the eccentric block 23, and a grinding disk 25 connected to the tool holder 24. The power motor 21 may be pneumatically or electrically implemented, and the present utility model is not limited thereto. The tool holder 24 is assembled with the polishing disk 25, but does not restrict the rotation of the polishing disk 25. Further, the grinding disc 25 can still rotate relative to the eccentric block 23 when the power motor 21 is not rotating. The polishing plate 25 is indirectly driven by the power motor 21, and the polishing plate 25 rotates in addition to revolving around the driving shaft 22 during rotation of the power motor 21. The grinding track of the grinding disk 25 is not purely circular, as seen in a single point of the grinding disk 25, but is shown at 50 in fig. 2. Furthermore, reference is made to EP0860235A2, US5,040,340 for a basic implementation of the random orbital grinding tool machine 20. Furthermore, the center of the polishing disk 25 has an eccentric distance 40 from the center of the driving shaft 22.

Referring back to fig. 1 and 3, the random orbital grinding tool machine 20 of the utility model has a friction member 26 disposed on the eccentric block 23, one end of the friction member 26 contacting the surface of the grinding disk 25 for a long period of time. The friction member 26 is mainly used for eliminating the autorotation of the grinding disc 25 when the power motor 21 stops running. That is, the present utility model stops the rotation of the polishing disk 25 for a short time when the power motor 21 is stopped by the friction member 26. The friction member 26 has a first state for providing a pre-pressure to the polishing disc 25 when the power motor 21 is not started, a second state for generating deformation as the power motor 21 is started and rotates with the polishing disc 25, and a third state for providing a braking force to the polishing disc 25 when the power motor 21 is stopped. Specifically, in the present utility model, when the power motor 21 is not started, the end of the friction member 26 facing the polishing disc 25 presses against the surface of the polishing disc 25 to provide pre-compression to the polishing disc 25. Subsequently, when the power motor 21 is started, the friction member 26 enters the second state. At this time, the eccentric block 23 rotates along with the driving shaft 22 of the power motor 21, the eccentric block 23 simultaneously rotates the friction member 26, and the moving speed of the friction member 26 at this time corresponds to the revolution speed of the polishing disc 25, so that the rotation speed of the polishing disc 25 is not affected, and the polishing efficiency and the polishing quality of the polishing disc 25 are maintained. On the other hand, since the grinding disk 25 rotates in a non-circular path, the end of the friction member 26 contacting the surface of the grinding disk 25 moves with the portion of the grinding disk 25 in contact therewith, and the friction member 26 moves by its own deformation in response to the end of the friction member 26 contacting the surface of the grinding disk 25 and can be maintained in contact with the grinding disk 25. As will be appreciated, the friction member 26 will rock in the second state. When the friction member 26 contacts one end (261) of the polishing disc 25, the end 261 is shifted from the original position of the end 261 when the polishing disc 25 rotates, and a shift range 41 of the end 261 is greater than or equal to twice the eccentric distance 40, but it is understood that the shift range of the end 261 does not refer to the sliding range of the end 261 on the surface of the polishing disc 25.

On the other hand, the power motor 21 is stopped, the driving shaft 22 is stopped, and the eccentric block 23 is stopped, and the friction member 26 is not rotated along with the eccentric block 23, and the second state is entered. The immobility of the friction member 26 is a resistance to the grinding disk 25 still in rotation, and the friction force generated by the friction member 26 contacting the surface of the grinding disk 25 will serve as a braking force for stopping the rotation of the grinding disk 25. In the present utility model, the friction member 26 is only required to resist the difference between the rotation speed of the polishing disc 25 and the eccentric block 23 in the third state, and the friction member 26 contacts the polishing disc 25 at a position closer to the center of the polishing disc 25, so that the friction member 26 bears less torque force, and the service life can be effectively prolonged. Before proceeding, the present utility model can avoid the problem that the grinding disc 25 rotates at a low speed without stopping with the power motor 21, so as to damage the surface of the grinding object.

Referring to fig. 3, in one embodiment, the friction member 26 has a base 262, a connecting portion 263 disposed on the base 262 and attached to the eccentric block 23, and at least one flexible contact portion 264 disposed on a side of the base 262 facing the polishing disc 25. The assembling portion 263 can be a hook or other structure for attaching the eccentric block 23. Furthermore, the free length of the flexible contact portion 264 is not limited to be equal to the distance from the bottom edge of the base portion 262 to the surface of the polishing disk 25, but may be slightly greater than the distance from the bottom edge of the base portion 262 to the surface of the polishing disk 25, thereby generating the pre-pressing force. The flexible contact portion 264 is a portion of the friction member 26 that is primarily deformed when the friction member 26 is in the second state. In this embodiment, the at least one flexible contact portion 264 may be implemented as a foot structure (265 as shown in the drawings), the foot structure 265 may be a solid member, the foot structure 265 has a bending direction, the bending direction is parallel to the rotation direction of the driving shaft 22, and the portion of the foot structure 265 formed with bending may be close to one end of the foot structure 265 contacting the surface of the polishing disc 25. Further, the friction member 26 may include a plurality of flexible contact portions 264, the plurality of flexible contact portions 264 may be arranged at intervals on a surface of the base 262 facing the polishing disc 25, the plurality of flexible contact portions 264 are not limited to being arranged at equidistant intervals, and the plurality of flexible contact portions 264 may be arranged in groups, as shown in fig. 1.

Referring to fig. 5 to 8, in addition to the above, in one embodiment of the present utility model, the at least one flexible contact portion 264 is a tubular structure (266 shown in the drawings), and an intraductal space extension 267 of the tubular structure 266 may be staggered with respect to the polishing platen 25 (shown in fig. 8 and 9) or parallel with respect to the polishing platen 25 (shown in fig. 5 and 6).

Referring back to fig. 1 and 3, the base 262 of the friction member 26 forms an assembly opening 268 for assembling the eccentric mass 23, and the assembly opening 268 corresponds to the eccentric mass 23 so that no significant lateral displacement occurs relative to the eccentric mass 23 when the friction member 26 is assembled. On the other hand, the assembling portion 263 is disposed near the assembling opening 268. In one embodiment, the assembling portion 263 is two hooks disposed on opposite sides of the assembling opening 268. In one embodiment, the friction member 26 has a retaining wall 269 surrounding the assembly opening 268.

Referring to FIG. 11, in one embodiment, the base 262 has a plurality of spaced blades 260 on a side thereof remote from the polishing platen 25. The vanes 260 create a wind flow within a shroud 27 of the random orbital sander tool 20 when the friction member 26 is in the first state, which can be used to dissipate heat from the structure. Also, according to the present embodiment, the friction member 26 may be disposed on a wind flow generating member 28 attached to the eccentric mass 23, the wind flow generating member 28 may be disassembled or assembled with respect to the eccentric mass 23, and the base 262 of the friction member 26 may be implemented as a base plate of the wind flow generating member 28.

Referring to fig. 3, the eccentric block 23 has a first portion 231 connected to the driving shaft 22, and a second portion 232 offset from the first portion 231. In one embodiment, the friction member 26 is coupled to the second portion 232. Further, the base 262 is higher in level than the bottom edge of the second portion 232 of the eccentric mass 23. Referring to fig. 11, in the embodiment in which the friction member 26 is disposed on the wind flow generating member 28, the wind flow generating member 28 is connected to the second portion 232.

Claims (14)

1. A random orbit grinding machine tool has a power motor, a driving shaft connected with the power motor, an eccentric block connected with the driving shaft, a tool holder arranged on the eccentric block, and a grinding disc connected with the tool holder and indirectly driven by the power motor,

the random orbit grinding tool machine is provided with a friction piece arranged on the eccentric block, the friction piece contacts the grinding disc, the friction piece is provided with a first state for providing precompression for the grinding disc when the power motor is not started, a second state for displacing along with the eccentric block when the power motor is started and generating deformation according to the rotation of the grinding disc, and a third state for providing braking force for the grinding disc when the power motor is stopped.

2. The random orbit milling machine tool according to claim 1, wherein the milling disc has an eccentric distance from the driving shaft, and the end of the friction member contacting the milling disc has an offset range of greater than or equal to twice the eccentric distance.

3. The random orbit grinding machine tool according to claim 2, wherein the friction member has a base portion, a coupling portion provided on the base portion and attached to the eccentric mass, and at least one flexible contact portion provided on a side of the base portion facing the grinding disc.

4. The random orbital grinding machine of claim 3 wherein the at least one flexible contact portion is a tubular structure.

5. The random orbit polishing machine of claim 4, wherein a line of space within the tube of the tubular structure intersects the polishing disc.

6. The random orbit polishing machine tool according to claim 4, wherein a line of space within the tube of the tubular structure extends parallel to the polishing disc.

7. The random orbital grinding tool machine of claim 3 wherein the at least one flexible contact portion is a foot structure having a bending direction that is parallel to the direction of rotation of the drive shaft.

8. The random orbit grinding tool machine of claim 3, wherein the base forms an assembly opening for assembling the eccentric mass, the set of engagement portions being in the assembly opening.

9. A random orbital grinding machine tool according to any one of claims 3 to 8 wherein the base has a plurality of spaced apart blades on a side remote from the grinding disk.

10. The random orbital grinding tool of any one of claims 3-8 wherein the eccentric mass has a first portion coupled to the drive shaft and a second portion offset from the first portion, the set of joints being coupled to the second portion.

11. The random orbital grinding machine of claim 10 wherein the base portion is higher in level than the bottom edge of the second portion of the eccentric mass.

12. The random orbit grinding machine tool according to claim 1, wherein the friction member is provided on a wind flow generating member attached to the eccentric mass.

13. The random orbital grinding machine of claim 12 wherein the eccentric mass has a first portion coupled to the drive shaft and a second portion offset from the first portion, the wind flow generating member being coupled to the second portion.

14. The random orbital grinding machine of claim 1 wherein the eccentric mass has a first portion coupled to the drive shaft and a second portion offset from the first portion, the friction member being coupled to the second portion.