JPH0753886Y2 - Belt sander - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt sander suitable for use in grinding stone products, for example.

[0002]

2. Description of the Related Art A conventional belt sander a has a structure as shown in FIG. In this belt sander a, for example, a first pulley d is directly connected to an output shaft s of an air motor m, a support arm e extending in a direction perpendicular to the first pulley d is provided, and a tip of the support arm e is provided. Supports the second pulley b in parallel with the first pulley d at a predetermined interval,
An endless paper belt p is stretched between the pulleys d and b. And the air hose h
If compressed air is supplied to the air motor m via the air motor m, the air motor m rotates at a high speed, which causes the paper belt p to move at a high speed in a certain direction, so that the ground surface pa of the lower surface side of the paper belt p is moved. The object W is ground by being pressed against a material W to be ground such as a stone product.

In order to adjust the tension of the paper belt p or to replace the paper belt p, the belt sander a is provided with an adjusting nut c at an intermediate position of the support arm e as shown in the figure. It was configured such that by rotating the adjusting nut c, the axial distance between the pulleys d and b can be increased or decreased.

However, in such a conventional belt sander a (hereinafter, referred to as "two-point type"), the paper belt a is mounted by being stretched around two shafts of a first pulley d and a second pulley b. Therefore, as shown in FIG. 11, when the operator holds the belt sander a and polishes the flat portion of the workpiece W, the paper belt p
When trying to press the polishing surface pa of the whole surface against the polishing target material W, the grasped hand touches the polishing target material W first, so it is unavoidable to press only the tip of the polishing surface pa. In addition to being inconvenient to use, it is difficult to efficiently perform polishing work with a good finished surface. So, as a belt sander without such problems,
Conventionally, for example, there is one disclosed in JP-A-1-321156 or JP-A-3-104551. According to this, a paper belt is stretched between three pulleys arranged at respective vertices of a triangle. (Hereinafter, referred to as “three-point hanging type”), even if the entire polishing surface of the paper belt is pressed against the workpiece W, a sufficient gap is provided between the workpiece W and the belt sander gripping portion. Since it is formed, the grasped hand does not touch the workpiece W,
Therefore, there was no problem with the belt sander a.

[0005]

However, even the conventional three-point type belt sander has the following problems. That is, one pulley can be moved in consideration of the convenience of replacing the paper belt, which makes it easy to remove the paper belt by changing the axial distance from the other pulley, and to easily give tension after mounting. However, since the length of the paper belt usually has a considerable variation, the position of the moving pulley will not be constant when a proper tension is applied. Since the position of the polishing surface is not constant, the gripping attitude of the belt sander during use is changed every time the belt is replaced, and inconvenience in this respect is a problem. Also, as in the two-point type belt sander, generally, one end in the width direction of the paper belt is most likely to be worn. Therefore, only the worn portion of the end is cut off and the width is reused. It is generally done. In such a case, the width of the paper belt is smaller than the width of the pulley. Therefore, there is a problem in that the tip of the pulley protrudes from the paper belt and comes into contact with the material to be polished, resulting in damage to the pulley. Furthermore, in this type of belt sander,
In order to prevent clogging of the paper belt, it is common practice to carry out the polishing work while flushing the polishing surface with water to wash away the polishing powder, etc. Some were equipped with a water supply system to do. However, there is no one provided with a special device for blowing away the polishing powder adhering to the polishing surface or the water leaked out for confirmation of the finished surface. There was the inconvenience of having to prepare a separate air device. Incidentally, as disclosed in, for example, Japanese Utility Model Publication No. 48-39267, air is blown toward the material to be polished from the rear of the polishing belt (close to the operator) in order to prevent the polishing powder from being blown to the operator. There was a configuration to form an air curtain by this, but because of its function it is configured to constantly blow air during the polishing work, so the water that has flowed out to wash away the polishing powder as described above There is a problem that it is blown off without exerting its function, and therefore, there has been a demand for a device that can blow out compressed air only when necessary.

The present invention has been made to solve the above-mentioned various problems of the related art, and can be mounted with the polishing surface always at a fixed position regardless of variations in the length of the paper belt to be used, and the width is narrow. An object of the present invention is to provide a belt sander equipped with a convenient compressed air injecting device that does not cause damage to the pulley even when the paper belt is reused.

[0007]

To this end, the invention according to claim 1 has a drive pulley that positively rotates, a middle pulley, and a tension pulley, and the paper belt is triangular between the three pulleys. A belt which is mounted around and the tension pulley is supported on the swing tip side of a tension arm which is swingably supported, and the axial distance between the tension pulley and the drive pulley or the middle pulley can be changed. In the sander, the tension arm is swingably supported via an eccentric collar, and the swing center of the tension arm can be displaced by rotating the eccentric collar. The invention according to claim 2 is characterized in that the drive pulley is configured to be held at a plurality of positions in the axial direction thereof. A third aspect of the invention is characterized in that a compressed air ejecting device capable of blowing compressed air in the vicinity of the paper belt and blocking the compressed air is provided.

[0008]

According to the structure of the first aspect, since the swing center of the tension arm supporting the tension pulley can be changed, the swing center can be moved even if the length of the paper belt to be mounted varies. This makes it possible to absorb the variation in the length of the paper belt and keep the tension pulley in the same position in the mounted state with appropriate tension.This makes the polishing surface of the paper belt against the belt sander body. Can always be set to the same position. According to the configuration of claim 2, the position of the drive pulley can be changed in the axial direction according to the width of the attached paper belt. Therefore, by providing the driving pulley with a brim edge for restricting the position of the paper belt in the width direction, the brim edge is moved. It can be installed so that the tip of the pulley does not protrude from the belt.

According to the third aspect of the present invention, since the compressed air jetting device is provided, it is not necessary to separately prepare an air gun or the like, and polishing work can be performed efficiently. Also, because the compressed air can be jetted only when necessary, it is possible to block the jet of compressed air during the polishing work, and therefore wash away the abrasive powder with water to prevent clogging of the paper belt. Even if polishing is performed, water is not unnecessarily blown off.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS. In this example, a belt sander A that uses an air motor M that rotates by compressed air as a drive source will be described as an example. 1 is a vertical cross-sectional view of the entire belt sander A of this example, FIG. 2 is a side view thereof, FIG. 3 is a front view, and FIG. 4 is a rear view.

In the figure, reference numeral 30 denotes a motor case, which has a substantially cylindrical shape with an appropriate diameter that can be easily grasped by an operator, and is formed so as to also serve as a grip portion of the belt sander A of this embodiment. An air motor M is installed in the left portion of the motor case 30 in the drawing.

Although this air motor M is conventionally well known, its explanation is omitted, but compressed air supplied by an air hose 4 connected to the rear end portion of the motor case 30 on the right side in the drawing through a hose joint 1. It is configured to be rotatable by. The air hose 4
Is connected to a compressed air supply device (not shown).

The compressed air supplied through the air hose 4 is supplied to the air motor M through the air passage 10. A straight valve 3 is provided at a midway position of the air passage 10. . This straight valve 3
Are rotatably supported in the diametrical direction of the motor case 30 so as to cross the air passage 10 and a water passage 9 described later. In the diameter direction of the straight valve 3, communication holes 3b and 3c are formed so as to correspond to the air passage 10 and the water passage 9, respectively, and the knob is attached to the tip of the straight valve 3. By rotating 5 to disconnect the air passage 10, the driving stop of the air motor M can be switched.
Here, the water passage 9 and the communication hole 3c constitute a water supply device, which will be described later.

Reference numeral 31 in the figure is a case cover made of synthetic rubber, for example, which is attached to the outer peripheral surface of the motor case 30 so that the motor case 30 can be easily gripped as a grip of the belt sander A. .

Further, as shown in FIG. 4, the motor case 3
A silencer 14 is attached to the rear end of 0,
Exhaust gas from the air motor M is configured to be open to the atmosphere via the silencer 14.

Next, a gear case 50 having a drive shaft 59 rotatably supported is attached to the left end side in the figure of the motor case 30 thus constructed. A cylindrical flange portion 50a is formed on the left side surface of the gear case 50 in the drawing, and the drive shaft 59 is supported by protruding from the cylindrical flange portion 50a to the left side in the drawing. On the other hand, the output shaft 33 of the air motor M projects in the gear case 50, and a gear 33a is formed at the tip of the output shaft 33. The gear 33a is meshed with and connected to a spur gear 54 attached to the rear end of the drive shaft 59, so that the rotation of the air motor M is transmitted to the drive shaft 59.

Further, a drive pulley 61 is attached to the tip of the drive shaft 59. The drive pulley 61 is attached so as to be movable in the axial direction of the drive shaft 59, and is biased to the right in the drawing by a compression coil spring 62 interposed between the drive pulley 59 and the drive shaft 59.

A brim edge 61c is formed at the rear end (right end in FIG. 1) of the drive pulley 61, and the brim edge 6 is formed.
A rubber non-slip cover 63 is attached to the outer peripheral surface of the belt hanging portion in front of 1c.

Further, on the rear end surface (see FIG. 5) of the drive pulley 61, two concave grooves 61a and 61b having different depths are formed.
(Hereinafter, referred to as "shallow groove 61a" and "deep groove 61b")
Drive shaft 59 while the drive shaft 59 is formed substantially orthogonally.
The locking projections 59a, 5 protruding on both sides in the diametrical direction.
9a is formed, and if the drive pulley 61 is moved to the left in the drawing against the biasing force of the compression coil spring 62 and the locking projections 59a, 59a are removed from the concave groove 61a (or 61b), The drive pulley 61 is the drive shaft 59.
With respect to the concave groove 6 of either one
When the locking projections 59a, 59a are inserted into the la (or 61b), the drive pulley 61 is configured so as not to rotate with respect to the drive shaft 59 and rotate integrally. Since the two recessed grooves 61a and 61b have different depths, when the locking protrusions 59a and 59a are inserted into the shallow recessed groove 61a, both of them are inserted into the deep recessed groove 61b. The drive shaft 59 is held at the tip side by the difference in depth.

In this way, the drive pulley 61 is moved leftward in the drawing to be rotatable, and by selecting a groove into which the locking projection 59a of the drive shaft 59 is inserted, the drive pulley 61 is driven. It is configured such that it can be held by selecting two axial positions.

Next, as shown in FIGS. 2 to 4 (or FIG. 6), a supporting edge 50b is formed so as to project below the gear case 50, and the front side of the supporting edge 50b (the left side in FIG. 2). ), A middle pulley 81 is rotatably attached via a support shaft 50c. The middle pulley 81 is formed to have substantially the same diameter as the drive pulley 61 and the same width as the belt hanging portion thereof. The middle pulley 81 is parallel to the drive pulley 61, and its tip end surface is formed by the guide pulley 61. It is supported in a state of being aligned with the tip end face when it is held in position via the deep groove 61b. A rubber anti-slip cover 83 is also attached to the outer peripheral surface of the middle pulley 81, like the drive pulley 61.

Next, an eccentric collar 65 is fitted on the outer peripheral side of the cylindrical flange portion 50a of the gear case 50,
Further, a tension arm 70 is attached to the outer peripheral side of the eccentric collar 65.

The eccentric collar 65 is formed in a ring shape whose outer circumference is eccentric with respect to the inner circumference by a predetermined dimension, and a screw hole 65a penetrating to the inner circumference side is formed on its circumferential side surface. A fixing screw 66 is attached to the screw hole 65a. Then, by loosening the fixing screw 66, the eccentric collar 6
5 is configured to be rotatable with respect to the cylindrical flange portion 50a, and conversely fixed by being tightened.

The tension arm 70 is formed by forming a strip plate into an arm shape having a predetermined length, and is rotatably supported with the eccentric collar 65 fitted in a support hole 70a formed at one end thereof. Has been done. As a result, the tension arm 70 is swingably supported on a plane orthogonal to the rotation axis of the drive shaft 59, that is, the drive pulley 61. Further, a long groove 70c is formed at an appropriate position on the side surface of the support hole 70a, and a fixing screw 67 having a knob 63 at the tip is inserted into the long groove 70c, and the fixing screw 67 has the eccentric collar 65. It is attached to the screw hole 65b formed in the. Then, by loosening the fixing screw 67, the tension arm 70
Is swingable with respect to the eccentric collar 65, and it is fixed so as not to swing by tightening in the opposite direction.

Further, as shown in FIG. 1 (or FIG. 2), the swinging distal end side of the tension arm 70 has a cut groove formed in the side surface thereof and is divided into two in the plate thickness direction, and the front side (left side in the drawing). A tension pulley 71 is rotatably attached to the tip of the split arm 70b via a support shaft 76. This tension pulley 71 is
It is formed in substantially the same manner as the middle pulley 81,
It is supported in parallel with the middle pulley 81 and with its front end surface aligned. Further, like the other pulleys 61 and 81, a rubber non-slip cover 73 is attached to the entire outer surface thereof. In the figure, reference numeral 69 denotes an adjusting screw. By rotating the adjusting screw 69, the rotation shaft center of the tension pulley 71 is changed to the other pulleys 61, 8
It is configured to be adjustable so that it is always parallel to the axis of rotation 1.

As shown in FIGS. 1 to 3, an endless paper belt 90 is wound between the pulleys 61, 71 and 81 which are supported in parallel with each other as described above so as to form a substantially triangular shape. Has been installed. The outer peripheral surface of the paper belt 90 is coated with fine particles of diamond, for example, so that a stone material or the like can be ground.

Reference numeral 105 in the drawing denotes a protective cover made of, for example, a synthetic resin, which prevents scattering of grinding powder wound up by the paper belt 90 or water described later to improve worker's safety and good workability. In order to secure it, the gear case 50 is attached so as to project above the paper belt 90 from the upper surface 50d.

The structure described above is the main body of the belt sander A of this embodiment, and the compressed air supplied by the air hose 4 causes the air motor M to rotate at a high speed, and this rotation is transmitted to the drive pulley 61 to cause the paper belt to rotate. 90 moves at a high speed in a certain direction. A portion of the paper belt 90 mainly located between the middle pulley 81 and the tension pulley 71 (hereinafter, referred to as "grinding surface 90").
It is configured such that the workpiece W can be ground by pressing "a") against the workpiece W such as a stone product.

Next, the belt sander A configured as described above is provided with a water supply device and a compressed air injection device. First, the water supply device is a device that supplies water to prevent clogging of the paper belt 90 and seizure of the material W to be ground, and further to wash away grinding powder and the like adhering to the paper belt 90 or the material W to be ground. The water cock 7 is attached to the rear end of the water passage 9 (rear end of the motor case) formed in the motor case 30 parallel to the air passage 10 to connect the hose 6, while the other end of the water passage 9 is connected. The water pipe 111 is connected, and the water pipe 111 extends along the outside of the motor case 30 to almost right above the paper belt 90. A water nozzle 114 is attached to the tip of the water pipe 111.

The above-mentioned straight valve 3 is also provided in the middle of the water channel 9. A communication hole 3c for the water channel 9 is formed in the diameter direction of the straight valve 3, and by rotating the straight valve 3 via the knob 5, the water channel 9 is communicated or cut off.
It is configured to switch between water supply and water interruption. Here, the water passage communication hole 3c is formed in the same direction as the air passage communication hole 3b, so that the switching between the water supply and the water cutoff is performed in conjunction with the start and stop of the air motor M. That is, at the same time that the air passage 10 is communicated, the water passage 9 is also communicated, and conversely, when the air passage 10 is blocked, the water passage 9 is also blocked.

The water cock 7 is provided with a knob 7a for adjusting the flow rate. By rotating the knob 7a, the water supply amount can be adjusted, and the water supply or the water cutoff can be switched. Has been done. Although not shown, the other end of the hose 6 is connected to, for example, a tap for water supply.

Next, the compressed air injection device is attached to blow away the grinding powder during the grinding operation or the water flowing out by the water supply device, and as shown in FIG. 1 or FIG. An air pipe 101 is connected to the rear end of the air passage 10 (on the hose joint 1 side of the straight valve 3) so as to be branched, and the air pipe 101 extends along the outer side of the motor case 30.
Is connected to an air valve 91 attached to the side surface of the. An air nozzle 102 extending from the air valve 91 to the vicinity of the paper belt 90 is attached.

As shown in FIG. 7, the air valve 91 includes a lever 93 and a switching rod 94 that is biased upward in the drawing by a compression coil spring 95. The lever 93 is pushed by, for example, a finger to push down the switching rod 94. Then, the air pipe 101 and the air nozzle 102 are communicated with each other, and the compressed air is blown out from the air nozzle 102. Conversely, if the finger is removed from the lever 93 and the lever 93 is brought into a free state, the switching rod 94 urges the compression coil spring 95. Is moved upward, the communication between the air pipe 101 and the air nozzle 102 is cut off, and the blowing of compressed air is stopped. That is, this compressed air injection device is configured to be able to blow compressed air in the vicinity of the paper belt 90 independently of switching of the straight valve 3, that is, starting and stopping of the air motor M.

The belt sander A of this embodiment is constructed as described above, and according to this construction, the following operational effects are achieved.

First, the belt sander A can be used as follows. That is, the compressed air is supplied into the air passage 10 by the air hose 4 connected to the compressed air supply device (not shown), and the water is supplied into the water passage 9 by the water hose 6 connected to the tap of the water supply. At this time, the flow rate adjusting knob 7a of the water cock 7 may be opened appropriately.

After this state, the operator holds the motor case 30 and rotates the straight valve 3 to the starting side via the knob 5, so that the air passage 10 and the water passage 9 are communicated with each other and the air motor M is operated. At the same time as starting, water flows out from the water nozzle 114. As a result, the workpiece W
Grinding work can be performed while water is flowing through.

When water supply is unnecessary, the flow rate adjusting knob 7a may be turned to close the water cock 7, and the knob 7a may be appropriately turned to adjust water supply or water cutoff or the amount of water supply. I'll do it.

The actual grinding operation is carried out mainly by pressing the grinding surface 90a (the portion located between the middle pulley 81 and the tension pulley 71) of the paper belt 90 against the material W to be ground. This grinding surface 9
0a is at a position forming the base of a triangle with the drive pulley 61 as the apex, and a constant step (gap) is provided between the motor case 30 and the lower end of the figure. Therefore, FIG.
As shown in FIG. 7, even when the motor case 30 is held substantially parallel to the flat ground material W, the operator's hand does not touch the ground material W and the ground surface 90a of the paper belt is not touched.
Since the grinding work can be performed by pressing the entire surface of the workpiece W against the workpiece W, the usability is good and the finished surface is beautiful and the grinding work can be performed easily and efficiently.

Further, since the belt sander A of this embodiment is provided with a water supply device, it is not necessary to prepare it separately prior to the grinding work, and if the water cock 7 is opened, the air motor M is started at the same time. Water is water nozzle 1
Since it flows out from 14, the operator can perform the grinding work efficiently while holding the belt sander A with one hand and flowing the water.

The belt sander A is also provided with a compressed air injection device, and it is not necessary to separately prepare it.
When the lever 93 of the air valve 91 is pushed regardless of whether the air motor M is started or stopped, compressed air is ejected from the air nozzle 102, and this operation can be performed with one hand while holding the belt sander A.

As described above, according to the belt sander A of this embodiment, it is not necessary to separately prepare a water supply device or a compressed air injection device, and the gripping of the belt sander A, the outflow of water, or the injection of compressed air is all performed with one hand. Also in this respect, the belt sander A is very easy to use and the grinding work can be performed efficiently.

Next, referring to FIG. 6, the paper belt 90.
The replacement procedure will be described. That is, if the fixing screw 67 is loosened, the tension arm 70 can be swung within the range of the long groove 70c, and the tension arm 70 is swung to the middle pulley 81 side so that the axial distance between the tension pulley 71 and the middle pulley 81 is increased. The paper belt 90 can be removed by contracting the paper belt 90, and conversely, after replacement, the tension arm 70 is swung to the side opposite the middle pulley to increase the axial distance between the tension pulley 71 and the middle pulley 81. It is possible to mount the pulleys 61, 71, 81 in a spanning manner with a proper tension applied to the pulleys.

Here, the position of the tension pulley 71 at which the tension of the paper belt 90 becomes appropriate is
It is not constant due to variations in the total length of the paper belt.
That is, the position of the ground surface 90a of the paper belt is not constant. However, this belt sander A
Considering the ease of use when gripping (the ease of gripping when considering the arrangement of the air valve 91, the knob 5, etc.), the position of the grinding surface 90a is, for example, the upper surface 50 of the gear case 50.
It is desirable that it is always parallel to d.

Therefore, in the belt sander A of this example, by moving the swing center of the tension arm 70, the variation of the entire length of the paper belt is absorbed, and the grinding surface 90
It is configured such that a can always be positioned parallel to the upper surface 50d of the gear case 50. That is, the tension arm 70 is swingably supported by the cylindrical flange portion 50a of the gear case 50 via the eccentric collar 65, and the eccentric collar 65 is formed so that the inner circumference is eccentric with respect to the outer circumference. By loosening the fixing screw 66 and rotating the eccentric collar 65 by a predetermined angle, the swing center of the tension arm 70 is moved. When the fixing screw 66 is loosened, the fixing screw 67 may be removed and the tension arm 70 may be moved to the tip side of the drive shaft 59.

In this way, by moving the swing center of the tension arm 70 in accordance with the entire length of the paper belt 90, the grinding surface 90a becomes the upper surface 5 of the gear case 50.
The belt sander A can be positioned in parallel with 0d at all times, which also makes the belt sander A of this example easy to use.

As described above, according to the belt sander A of this embodiment, the entire grinding surface 90a can be pressed against the work W to be ground, and the grinding work can be performed. In many cases, only the ends of the surface 90a are pressed against each other (see FIG. 11), and therefore the widthwise ends of the paper belt generally decrease most quickly. Here, since the paper belt coated with fine diamond particles is very expensive, it is often uneconomical to replace it with a new one. Therefore, it has been customary in the past to cut the end portion of the paper belt, that is, to reduce the width of the paper belt for reuse.

The belt sander A of this example can also be applied to the narrowed paper belt 90 '. That is, as shown in FIG. 9, by moving the drive pulley 61 to the tip side of the drive shaft 59, the narrow edge of the narrow paper belt 90 'is substantially aligned with the tips of the middle pulley 81 and the tension pulley 71. State, and drive this paper belt 90 'to the drive pulley 6
It can be mounted in a state of being in contact with the first brim 61c. From this, both pulleys 81, 71 are
The leading end of the paper belt 90 'does not protrude from the leading edge of the paper belt 90' and is directly pressed against the workpiece W to be damaged, and even this narrow paper belt 90 'can be ground without any trouble. You can do it.

The drive pulley 61 is moved as follows. First, the drive pulley 61 is moved to the front end side (left side in the drawing) of the drive shaft 59 against the compression coil spring 62 to release the engagement between the deep groove 61b and the locking projections 59a, 59a of the drive shaft 59. To do.
As a result, the drive pulley 61 moves the drive shaft 59.
Can be rotated with respect to. Drive pulley 61 in this state
Is rotated about 90 ° and then returned to the right in the drawing by the urging force of the compression coil spring 62. Thereby, the locking protrusions 59a, 5
9a is inserted into the shallow groove 61a, and the drive pulley 6
1 is held by being displaced toward the tip end side of the drive shaft 59 by the difference in depth between the concave grooves 61a, 61b.

In this way, by displacing the drive pulley 61, it is possible to perform the grinding operation with the paper belt 90 'narrowed in width being always aligned with the tips of the tension pulley 71 and the middle pulley 81. As a result, even a narrow paper belt 90 'can be ground without any trouble, and the paper belt can be used effectively.

The belt sander A described above is one embodiment of the present invention, and the structure thereof is not limited to that described above, and various embodiments are possible without departing from the scope of the utility model registration claim. Can be implemented.

[0051]

According to the first aspect of the present invention, the polishing surface can be set at the same position regardless of the variation in the length of the attached paper belt, so that the polishing work can always be performed in the same gripping posture. It can be done and its usability can be improved.

According to the second aspect of the invention, by moving the drive pulley according to the width of the paper belt to be mounted, the worn belt is cut off and the narrowed paper belt is reused. , You will be able to perform polishing work without worrying about damage to the pulley.

According to the third aspect of the present invention, since the compressed air injection device is provided, it is not necessary to separately prepare an air device such as an air gun as in the conventional case, and compressed air is injected only when necessary. This prevents water from being accidentally blown off when the polishing surface is rinsed with water in order to prevent clogging of the paper belt.

[0054]

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an entire belt sander according to an embodiment of the present invention.

FIG. 2 is a side view of a belt sander.

FIG. 3 is a view taken in the direction of arrow III in FIG. 2 and is a front view of the belt sander.

4 is a view on arrow IV of FIG. 2, which is a rear view of the belt sander. FIG.

FIG. 5 is a rear view of the drive pulley.

FIG. 6 is a front view of the gear case and is a plan view showing the positional relationship between the eccentric collar and the tension arm.

FIG. 7 is a partial vertical cross-sectional view of an air valve.

FIG. 8 is an explanatory diagram of an example of using a belt sander.

FIG. 9 is a partial cross-sectional view of a belt sander tip portion,
It is explanatory drawing which shows the displacement method of a drive pulley.

FIG. 10 is an overall perspective view showing a conventional example of a belt sander.

FIG. 11 is an explanatory diagram of a usage example of a conventional belt sander.

[Explanation of symbols]

 A, a Belt sander W Grinding material M, m Air motor 30 Motor case 50 Gear case 59 Drive shaft 59a Locking protrusion 61 Drive pulley 61a Shallow groove 61b Deep groove 65 Eccentric collar 70 Tension arm 71 Tension pulley 81 Middle pulley 90, p Paper belt 90a, pa Grinding surface 102 Air nozzle 105 Protective cover 114 Water nozzle

Claims (3)

[Scope of utility model registration request] 1. A drive pulley that positively rotates, a middle pulley, and a tension pulley. A paper belt is mounted in a triangular shape between the three pulleys, and the tension pulley is swingably supported. In a belt sander configured to be supported on the swinging tip side of a tension arm and capable of changing the axial distance between the drive pulley or the middle pulley, the tension arm swings through an eccentric collar. A belt sander that is movably supported and is configured such that the swing center of the tension arm can be displaced by rotating the eccentric collar. 2. The belt sander according to claim 1, wherein the drive pulley is configured to be held at a plurality of positions in the axial direction thereof. 3. The belt sander according to claim 1, further comprising a compressed air injection device capable of blowing compressed air in the vicinity of the paper belt and blocking the compressed air.