JPH0160392B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

This invention relates to a dry blasting device that blasts an object by spraying an abrasive material made of hard particles together with a fluid such as air at high speed. The present invention relates to a blasting device that has been improved so that fine adjustment for optimizing suction of abrasive material is not required.

[Conventional technology]

Blasting processing achieves an average grinding effect in each part of the target object, does not cause waste fluid pollution like degreasing or pickling processing, is non-directional grinding, avoids stress concentration, and reduces the amount of material to be ground. It is often used for removing scale, forming a base, or removing burrs from the surface of metal materials due to various advantages such as reducing the amount of grinding and not wasting material.Furthermore, since it can grind hard materials relatively easily, It is also applied as a means of arts and crafts such as stone carving, wood carving, and forming pear-shaped patterns on glass surfaces. As a blasting device for performing such blasting processing, a so-called suction type blasting device is most commonly employed. No. 6 of the present application
The figure shows a typical structure of a nozzle gun 1 of this suction type blasting device. A generally cylindrical container-shaped induction chamber 2 is formed in which the abrasive material is guided from a hopper (not shown) via a hose.
A nozzle pipe 4 whose inner diameter is narrowed by a diameter-reduced conical inner surface 3 is passed through the front end of the induction chamber 2 to the outside. Inside the reduced diameter conical inner surface 3 of the induction chamber 2, a reduced diameter end portion 7 of an air jet tube 6 inserted into the induction chamber from the rear wall 5 of the induction chamber is arranged. This air jet pipe 6 is connected to a compressor (not shown), which allows air at relatively high pressure (4 to 6 atmospheres) to be sent. Further, the air jet pipe 6 is connected to the rear wall 5 of the induction chamber.
It is possible to adjust the movement in the axial direction within the hole 8 bored in the hole 8. Note that reference numeral 9 is a set screw for fixing the air jet tube 6 whose axial position has been adjusted. When air is ejected from the tip of the air ejection pipe 6, the abrasive material guided into the annular gap between the inner surface of the reduced diameter cone 3 and the outer periphery of the air ejection pipe 6 by this high-speed air flow is In this way, an air jet suitably mixed with abrasive material is injected to the outside through the nozzle pipe 4.

[Problems to be solved by the invention]

By the way, the above-mentioned conventional suction type blasting device has the following problems. First, since the inner diameter of the air ejection tube 6 is quite small, the cross-sectional area of the air flow ejected from the tip of the nozzle tube 4 is small, so that only a small area can be treated. This means that in order to give sufficient speed to the air jetting out from the air jetting tube 6 with the output of the relatively small compressors that currently exist, the inner diameter of the tip of the air jetting tube 6 must be narrowed down considerably as described above. This is due to the fact that there is no such thing. This means that the air jet pipe 6
Increasing the flow rate of the airflow ejected from the engine while maintaining its speed would require a huge compressor, which is simply not possible due to cost considerations. Second, in the air flow ejected from the air ejection pipe 6,
It is difficult to make fine adjustments to mix in the abrasive at the optimum ratio. In other words, as is clear from Fig. 6, since the abrasive material drawn around the narrowed airflow is placed on the narrowed airflow,
Finding the optimal shape of the annular gap formed by the inner surface of the reduced diameter cone 3 and the outer periphery of the air jet tube 6 requires very delicate adjustment, and since this gap is not visible from the outside, it is difficult to make adjustments. It takes a lot of time. For example, if the air jet pipe 6 is moved back too far and the gap widens too much, too much of the abrasive material will enter the gap, absorbing the kinetic energy of the air flow, and making it impossible to obtain a sufficient flow velocity at the nozzle tip. Alternatively, the air flow expands and impinges on the inner surface of the reduced diameter cone, which may significantly reduce the kinetic energy of the air flow or result in insufficient negative pressure to attract the abrasive material. Furthermore, if the air jet pipe 6 is advanced too far and the above-mentioned gap becomes too narrow, sufficient abrasive material will not be mixed into the air flow. Further, even if the position of the tip of the air jet tube 6 is swayed in the direction perpendicular to the axis, the mixing ratio of the abrasive material changes greatly. This invention was devised under the above circumstances, and it solves the above-mentioned problems of the conventional example, significantly increases the flow rate of the jet from the nozzle tip, and improves work efficiency. It is an object of the present invention to provide a dry blasting device that is improved so as to eliminate the need for troublesome fine adjustments for sucking out cleaning material.

[Means to solve the problem]

In order to solve the above conventional problems, the present invention takes the following technical measures. That is, the present invention includes a low-pressure air supply device including a blower, an abrasive material supply device, and a granular air supply device supplied from the abrasive material supply device by a high-volume, high-speed, low-pressure air flow sent from the low-pressure air supply device. A dry blasting device comprising a nozzle gun for injecting a dry abrasive material, the nozzle gun having a front end of a cylindrical peripheral wall closed with the front wall, and an air conveying pipe from the low pressure air supply device being directly connected to the nozzle gun. An air chamber is connected to the air supply device, and a large amount of low-pressure air is directly supplied from the air supply device with little resistance. An abrasive material supply pipe through which the granular dry abrasive material of the abrasive material supply device is sent, and a low-pressure air jet hole formed through the front wall in a region adjacent to and surrounding the opening of the abrasive material supply pipe. and a guide tube whose proximal end is connected to a portion of the front wall surrounding the low-pressure air ejection hole and which extends a predetermined length forward from the front wall.

[Action and effect]

The air chamber of the nozzle gun is directly connected to the air conveying pipe from the low-pressure air supply device, so a large amount of low-pressure air is supplied to this air chamber, and the air introduced into this air chamber is directed against the front wall. A large amount of high-speed air is ejected from the low-pressure air injection hole formed through the hole. In the path from the low pressure air supply device to the nozzle gun,
This is because only the resistance of the orifice of the air jet hole drilled in the front wall acts.In addition to using a large flow rate blower as a low pressure air supply device,
By enlarging the opening of the air jet hole, it is possible to form a high-speed air jet with an incomparably large flow rate compared to the conventional method. In addition, the air from the air outlet is not directly released into the atmosphere, but is ejected into the space surrounded by the guide tube, so the airflow is created by a curtain surrounding the opening of the abrasive material supply tube. In addition to forming a flow, the static pressure at the front of the air chamber, especially at the opening, is sufficiently lowered, and a sufficient amount of fluid is generated to correspond to the large amount of air flow injected from the air outlet. Abrasive material will be sucked out of the opening of the supply tube and mixed into the air stream. As a result, a large amount of high-speed airflow containing sufficient abrasive material is ejected over a wide cross-sectional area defined by the guide tube, resulting in a dramatic improvement in work efficiency. In addition, since both the air jet hole and the abrasive material supply pipe opening are configured with fixed holes drilled in the front wall of the air outlet, they are not connected to the reduced diameter conical inner surface of the inner end of the nozzle pipe, as in the conventional example. You don't have to do the troublesome work of finely adjusting the gap between the air outlet and the air outlet. As mentioned above, this means that a high-speed, large-flow airflow can be injected from the air jet hole, and that the static pressure in front of the front wall of the air chamber can be reliably and sufficiently reduced by the action of the guide pipe. This is an incidental effect due to Furthermore, since the air supply device is a low-pressure blower, the conduit for supplying air to the nozzle gun can be constructed with inexpensive items such as low-pressure hoses.
Coupled with the fact that the air supply device itself is inexpensive, this also has the effect of significantly reducing the cost of the device, reducing running costs, and extending the life of the device.

[Explanation of Examples]

Embodiments of the present invention will be specifically described below with reference to FIGS. 1 to 5. FIG. 1 shows the overall configuration of an example of the apparatus of the present invention. Reference numeral 11 indicates a hopper as an abrasive material supply device, and the granular dry abrasive material S stored in this hopper is supplied to a nozzle gun 13 to be described later through a flexible conduit such as a hose 12. It's summery. In this example, a means 15 for feeding low-pressure air into the container 14 under the chute of the hopper 11 is provided in order to improve the flow of the abrasive material within the pipe. On the other hand, 16 indicates a blower as a low-pressure air supply device, and a large amount of air flow generated by this blower 16 is sent to the nozzle gun 13 via a flexible pipe such as a hose 17. FIGS. 2 to 5 show details of an embodiment of the nozzle gun 13 having the characteristic parts of the present invention. This nozzle gun 13 has a substantially cylindrical air chamber 19 equipped with a branched introduction pipe 18 to which the relatively large-diameter hose 17 is directly connected. Low-pressure air is fed directly with little resistance. A front wall 20 is formed at the front end of the air chamber 19. On the other hand, inside the air chamber, there is a rear wall 22 and a front wall 20.
An abrasive material supply pipe 23 is disposed to pass through the gap, and this abrasive material supply pipe 23 is opened at the center of the front surface 20a of the front wall 20, and this opening is used for the abrasive material to flow out. A hole 21 is formed. Further, a hose 12 extending from the hopper 11 is connected to a connecting pipe 24 attached to the rear end of the abrasive material supply pipe 23. In the embodiment, a sleeve 25 made of wear-resistant hard metal is inserted into the supply pipe 23 to prevent wear and tear of the supply pipe 23 caused by the abrasive material. Further, an air chamber 1 is provided in a portion of the front wall 20 adjacent to and surrounding the abrasive material outflow hole 21.
Air ejection holes 26 are provided that penetrate from the inside of the housing 9 to the outside. The front shape of the air blowout hole 26 is not limited, and may be a round hole 26a as shown in FIG. It may be a hole 26b, or it may be an annular hole 26c as shown in FIG. However, in order to minimize the resistance when air blows out from the blow-off hole 26, it is preferable to make the hole widen at the tip side and have a tangle-like shape in longitudinal section, as shown in FIG. Moreover, the angle of the axis of the hole 26 is
As shown in FIG. 2, if the tip is inclined so that it intersects the axis of the abrasive material outflow hole 21 at a location relatively close to the front wall 20a, the effect of sucking out the abrasive material S is improved. At the same time, it is convenient for spreading the sucked out abrasive material S over the entire cross section of the guide tube 27, which will be described later, and expanding the cross section of the airflow containing the abrasive material. Further, a proximal end of the front wall 20 of the air chamber 19 is connected to a portion surrounding the low-pressure air jet hole 26,
A guide tube 27 is also provided that extends forward a predetermined length from the front wall. If an expanding cone 27a is formed on the inner periphery of the guide tube 27, as shown by the imaginary line in FIG. It is preferable. In the above configuration, when the blower 16 is started to generate airflow, a large amount of low-pressure airflow is sent directly to the air chamber 19 of the nozzle gun 13 via the relatively large diameter hose 17, and the front wall of the Air is ejected from the air ejection hole 26 penetrated through the guide tube 20 at high speed into the internal space of the guide tube 27 . The airflow ejected from the air ejection holes 26 has a large flow rate and high speed that is incomparable to the airflow generated by the nozzle of a blasting device that uses a conventional compressed air generator as an air supply source. This is because, in the present invention, a low-pressure air generator consisting of a blower is used as an air supply source, a large amount of air from the air generator is directly introduced into the air chamber, and the nozzle This is a synergistic effect in that the air injected from the front wall is substantially only affected by the resistance of the orifice of the air jet hole formed in the front wall, and that the cross section of the air jet hole can be enlarged. The air ejected from the air ejection holes is not directly emitted into the atmosphere, but is ejected at a large flow rate into the inner space of the guide tube 27 connected to the front wall 20, so that the air jet is not directly emitted into the atmosphere. Together with the formation of a curtain surrounding the scavenging material outflow hole 21, the static pressure within the guide pipe, especially at the front of the front wall 20, is reliably and sufficiently reduced, and the air is blown out at a large flow rate as described above. A sufficient amount of abrasive material commensurate with the flow is sucked out from the abrasive outlet hole and mixed into the air flow. Then, the high-speed, large-flow air flow mixed with sufficient abrasive material is expanded to a sufficient cross-sectional area corresponding to the cross-section of the guide tube, and this collides with a wide area of the target object, resulting in efficient plasting action. to do. It goes without saying that the scope of the present invention is not limited to the embodiments described above. For example, as an air chamber 19 into which air from a blower is introduced,
In the embodiment, the air chamber is formed in the shape of a cylindrical container, but the air chamber can be regarded as a long one containing a large diameter hose, and a hose for supplying abrasive material can be inserted into this large diameter air chamber. The tip may be opened at the front of the front wall of the air chamber. Further, the purpose of displaying the abrasive material and the blasting process is not limited.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of the blasting device of the present invention;
Figure 2 is a vertical cross-sectional view of the nozzle gun of the above device;
Figures 4 and 5 are views corresponding to the view taken along line A-A in Figure 2, showing aspects of the air jet holes formed in the front wall, and Figure 6 is an explanatory view of the conventional example. be. 11... Abrasive material supply device (hopper), 13...
Nozzle gun, 16...Air supply device (blower),
19...chamber, 20...front wall, 21...abrasive material outlet, 26...air blowout hole.

Claims (1)

[Claims] 1. A low-pressure air supply device comprising a blower, an abrasive material supply device, and a high-volume, high-speed, low-pressure air flow sent from the low-pressure air supply device, supplied from the abrasive material supply device. A dry blasting device comprising a nozzle gun that sprays a granular dry abrasive, the nozzle gun having a front end of a cylindrical peripheral wall closed with a front wall, and an air conveying pipe from the low pressure air supply device directly connected to the nozzle gun. an air chamber connected to the air supply device and directly supplied with a large amount of low-pressure air from the air supply device with little resistance; The abrasive material supply pipe through which the granular dry abrasive material of the abrasive material supply device is fed, and the low-pressure air jet formed through the front wall in a region adjacent to and surrounding the opening of the abrasive material supply pipe. Dry blasting comprising: a hole; and a guide tube having a proximal end connected to a portion of the front wall surrounding the low-pressure air jetting hole and extending a predetermined length forward from the front wall. Device.