CN109807756B

CN109807756B - Sand blasting machine

Info

Publication number: CN109807756B
Application number: CN201910062284.XA
Authority: CN
Inventors: 陶跃华
Original assignee: Taizhou Kailiang Glasses Co ltd
Current assignee: Taizhou Kailiang Glasses Co ltd
Priority date: 2019-01-23
Filing date: 2019-01-23
Publication date: 2021-03-23
Anticipated expiration: 2039-01-23
Also published as: CN109807756A

Abstract

The invention relates to a sand blasting machine, which comprises a machine shell with a working cavity, wherein a lower roller, an upper roller, a bearing belt wound on the lower roller and the upper roller, a shaping wheel arranged between the upper roller and the lower roller and a first power assembly driving the upper roller to rotate are arranged in the working cavity; at least two shaping wheels are arranged and respectively close to the two sides of the bearing belt; the outer side surface of the bearing belt is wound on the circumferential surface of the shaping wheel, and a material placing area for placing a workpiece is formed; the surface of the bearing belt is hollowed with a plurality of blanking holes for sand to pass through; the sand blasting mechanism of the material placing area with the nozzle facing is arranged above the material placing area, so that the limitation on the shape of the workpiece is eliminated, the sand blasting is carried out on all the surfaces of the workpiece in batch mode, and the sand blasting mechanism has the advantages of high sand blasting quality and high covering uniformity.

Description

Sand blasting machine

Technical Field

The invention relates to the field of sand blasting equipment, in particular to a sand blasting machine.

Background

The sand blasting adopts compressed air as power to form a high-speed spray beam to spray materials: copper ore sand, quartz sand, carborundum, iron sand, Hainan sand and the like are sprayed to the surface of a workpiece to be treated at a high speed, so that the appearance or the shape of the outer surface of the workpiece surface is changed. Due to the impact and cutting action of the abrasive on the surface of the workpiece, the surface of the workpiece obtains certain cleanliness and different roughness, the mechanical property of the surface of the workpiece is improved, the fatigue resistance of the workpiece can be improved, the adhesive force between the workpiece and a coating is increased, the durability of a coating is prolonged, and the leveling and decoration of the coating are facilitated.

Chinese patent with publication number CN206405925U discloses a sand blasting machine, which comprises a support, a sand blasting chamber, a dust removing device and a feeding box, wherein the sand blasting chamber, the dust removing device and the feeding box are arranged on the support, and a workbench and a sand blasting gun are arranged in the sand blasting chamber; the method is characterized in that: the device also comprises an air supply structure, a feeding structure, an air gun and a speed regulating device arranged outside the sand blasting chamber; the workbench is a controllable rotary table, and the controllable rotary table is controlled by a speed regulating device; the air supply structure is arranged between the sand blasting gun and the dust removal device and comprises an air supply pipe and an air pipe regulating device arranged on the air supply pipe; the air gun is connected with the air pipe regulating device through an air supply pipe; the feeding structure is arranged between the sand blasting gun and the feeding box and comprises a material pipe and a material pipe regulating device arranged on the material pipe; the inlet of the sand blasting gun is connected with a manifold with a three-way joint, and the other two joints of the manifold are respectively connected with an air pipe and a material pipe; the front surface of the sand blasting chamber is an inclined surface, an operation opening is formed in the inclined surface, and operation gloves are arranged in the operation opening.

The prior art has the defects that the rotary workbench is adopted to perform uniform sand blasting treatment on all surfaces of the workpiece except the bottom surface in a workpiece rotating mode, but the rotary workbench also has certain requirements on the shape of the workpiece so as to be convenient for clamping and cannot perform all-round sand blasting; when the number of workpieces is large and the shapes are complex, such as spectacle frames, the comprehensive sand blasting cannot be uniformly carried out on a large scale.

Disclosure of Invention

The invention aims to provide a sand blasting machine, which solves the problem that large-batch and uniform all-around sand blasting cannot be carried out and has the advantage of simultaneously carrying out all-around uniform sand blasting on a plurality of workpieces.

The technical purpose of the invention is realized by the following technical scheme:

a sand blasting machine comprises a machine shell with a working cavity, wherein a lower roller, an upper roller, a bearing belt wound on the lower roller and the upper roller, a shaping wheel arranged between the upper roller and the lower roller and a first power assembly driving the upper roller to rotate are arranged in the working cavity; at least two shaping wheels are arranged and respectively close to the two sides of the bearing belt; the outer side surface of the bearing belt is wound on the circumferential surface of the shaping wheel, and a material placing area for placing a workpiece is formed; the surface of the bearing belt is hollowed with a plurality of blanking holes for sand to pass through; and a sand blasting mechanism with a nozzle facing the material placing area is arranged above the material placing area.

By adopting the technical scheme, the bearing belt sequentially winds the lower roller, the shaping wheel and the upper roller, a flexible material placing area is formed, the workpiece can continuously fall and turn over in the process of rising along with the bearing belt, so that the workpiece at the bottom continuously becomes an upper layer, and the sand blasting mechanism continuously performs sand blasting on the workpiece in the process, so that the sand blasting on all surfaces of the workpiece in batch is realized, and the workpiece is not required to be clamped in the turning mode, so that the limitation on the shape of the workpiece is eliminated; and the redundant sand sprayed to the surface of the carrier belt is discharged or reused through the blanking holes, so that the influence on the sand blasting effect caused by accumulation on the belt surface is avoided, the sand blasting of the workpiece has very good continuity, and the sand blasting quality and the covering uniformity are improved.

The invention is further configured to: the carrier tape is distributed with a plurality of groups of damping stripes along the length direction, and the damping stripes comprise two splayed twills and straight stripes which are arranged at intervals with the twills along the length direction of the carrier tape; the opening directions of the two twill lines face the revolving direction of the bearing belt.

Through adopting above-mentioned technical scheme, the damping stripe can improve the work piece and carry the effect of pulling that the area drove to rise, and splayed stripe wherein also provides the effect of gathering to middle direction when providing the effect of pulling to concentrate on the sandblast region with the work piece.

The invention is further configured to: sandblast mechanism is including wearing to locate the pivot of working chamber, drive pivot pivoted second power component, be fixed in pivot on the rocker and at least two shower nozzles of arranging in the rocker along the width direction that bears the weight of the area, the pivot is rotated and is connected in the casing, the shower nozzle orientation is put material district and end connection and is sent sand pipe and pneumatic tube, the rocker is along the direction of delivery swing back and forth that bears the weight of the area.

Through adopting above-mentioned technical scheme, second power component drives the pivot and rotates at the sandblast in-process, and then drives the shower nozzle swing on rocker and the rocker to improve the coverage of sandblast, improve the degree of consistency of sandblast along with bearing the rolling of area with the cooperation work piece.

The invention is further configured to: the second power assembly comprises a transmission disc, a second motor, a second main rocker arm, a swing arm, a second sub rocker arm and a transmission rod, wherein the axis of the transmission disc is parallel to the rotating shaft; the both ends of transfer line are articulated with swing arm and the sub-rocking arm of second respectively, and wherein the one end of being connected with the sub-rocking arm of second is fixed with the adapter, the adapter slides along the length direction of the sub-rocking arm of second and connects in the sub-rocking arm of second.

Through adopting above-mentioned technical scheme, the second motor rotates and drives the rotation of second owner rocking arm to drive the transfer line straight reciprocating motion who is restricted to can only slide through the swing arm, and then drive the reciprocal swing of pivot, thereby realize that the shower nozzle can be continuous carry out small amplitude reciprocal swing, improve the degree of consistency of sandblast.

The invention is further configured to: the inner wall of the sand conveying pipe is fixedly provided with an inner pipe, the inner pipe is communicated with a branch pipe which penetrates through the sand conveying pipe and conveys gas to the inner pipe, the inner pipe is provided with a notch with an opening facing to the inner cavity of the sand conveying pipe, and the notch is distributed along the length direction of the inner pipe.

By adopting the technical scheme, the airflow enters the inner pipe through the branch pipe, and the airflow of the inner pipe enters the sand conveying pipe through the notches at all parts and assists the sand conveying pipe to convey, so that the smoothness and the uniformity of sand conveying are improved; in addition, the sand material is dried to a certain degree, and can be cleaned in a jet air pressure mode when the sand feeding pipe has little sand or no sand, so that the condition of silting in the pipe is reduced.

The invention is further configured to: a pressure varying piece is fixed in the middle of each notch, the diameter of each pressure varying piece is the same as the inner diameter of the inner pipe, a compensation hole communicated with an inner pipeline of the inner pipe is formed in the center of each pressure varying piece, and each notch is V-shaped and extends to the center of the inner pipe.

Through adopting above-mentioned technical scheme, the structure of similar nozzle has been formed between incision and the vary voltage piece, when the air current of inner tube flows on the inner tube, because of receiving blocking and striking of vary voltage piece from time to time, make most air current produce the dive effect to sand feeding pipe through the incision from the inner tube, especially the consistency of sand material is great, for the quick transmission of air current in the inner tube, can form the phenomenon similar to the siltation for the inner tube in the sand feeding pipe, local pressure drag increases, the sand material that flows at this moment wants to change away the inner tube because of blockking up, just at this moment with the dive fluid production striking of nozzle department, form stronger turbulent flow, thereby force the sand material to flow and eliminate the siltation.

The invention is further configured to: a second filter screen is arranged at the opening of the notch, and the diameter of the compensation hole is one third to one half of the diameter of the transformer plate.

By adopting the technical scheme, the compensation holes are communicated with the fluid channel in the inner tube, the aperture of the compensation holes can not be smaller than one third of the diameter of the pressure changing piece in order to ensure that the pressure changing piece at which the compensation holes are located blocks fluid, so that the pressure changing piece impacts the fluid to change the direction of the fluid to form a turbulent flow part, the viscosity of sand is high, the required impact turbulent flow is high, and the diameter of the compensation holes can not be larger than one half.

The invention is further configured to: the inner wall of the working cavity is provided with two air curtain air outlets which are respectively separated from two sides of the spray head and incline downwards towards the spray head, and the casing is provided with fans which respectively supply air to the air curtain air outlets.

Through adopting above-mentioned technical scheme, on the one hand the air curtain can prevent inside dust to raise, plays the effect of protection to each transmission structure of top, and on the other hand two air curtains is relative and slope downwards, will appear common decurrent air current after converging to help improving the sandblast.

The invention is further configured to: a feeding port for the workpiece to enter and exit is formed in one side of the machine shell, the lower roller is close to the feeding port, and the lower roller is positioned below the feeding port in height; the lower part of the working cavity is provided with a sand storage cavity, the outer side of the feeding port of the shell is provided with a feeding hopper communicated to the sand storage cavity, and the feeding hopper is provided with a first filter screen for blocking a workpiece.

Through adopting above-mentioned technical scheme, can be between through the supplementary of the reinforced realization sand material of feeder hopper on the one hand, on the other hand can provide the filtration when the work piece is concentrated to be taken out to realize the separation and the recollection of sand material.

The invention is further configured to: a tensioning roller which is abutted against the inner side of the bearing belt is arranged below the shaping wheel, a transfer plate for collecting sand leaked from the blanking hole is arranged between the tensioning roller and the bearing belt above the tensioning roller, and an installation groove for obliquely embedding the transfer plate and a guide groove for connecting the installation groove and the sand storage cavity are arranged on the inner wall of the casing; the lateral wall of casing is provided with the sand conveying passageway that communicates to the sand storage chamber and locates to send the sand conveying machine that sand passageway in carried the sand material to the casing top.

By adopting the technical scheme, the transfer plate can shield and collect the sand materials which are discharged through the blanking holes on the upper bearing belt, so that the transmission failure of the belt and the roller due to the fact that the sand materials fall into the inner side of the bearing belt is avoided; in addition, the sand can be collected to improve the utilization rate.

In conclusion, the invention has the following beneficial effects:

1. the movable flexible material placing area is adopted, the workpiece is forced to turn over when moving, so that the sand blasting on all the surfaces of the workpiece in batch is realized, and the sand blasting quality and the covering uniformity are improved; the workpiece is not required to be clamped in the overturning mode, and the limitation on the shape of the workpiece is eliminated;

2. the swing type spray head is adopted, so that the coverage surface of sand blasting is improved, and the uniformity of sand blasting is further improved;

3. an inner sleeve sand feeding mode is adopted, so that the smoothness and the uniformity of sand feeding are improved; (ii) a

4. The utilization rate of the sand material is improved by adopting a multiple recovery structure.

Drawings

FIG. 1 is an overall configuration diagram of a blasting machine of embodiment 1;

FIG. 2 is an internal structural view of the blasting machine of embodiment 1;

FIG. 3 is a schematic view of the internal structure of the blasting machine of embodiment 1;

FIG. 4 is a construction view of a removing case of the blasting machine of embodiment 1;

FIG. 5 is a structural view of a blasting mechanism of embodiment 1;

FIG. 6 is an internal structure view of a sand feed pipe according to example 1;

FIG. 7 is an enlarged view at A of FIG. 6 of embodiment 1;

fig. 8 is a structural diagram of a second power module of embodiment 1.

In the figure, 1, a housing; 2. a material loading mechanism; 3. a sand blasting mechanism; 11. a working chamber; 12. a sand storage cavity; 13. an air curtain outlet; 14. a feed port; 15. a machine door; 16. a feed hopper; 17. a first filter screen; 18. a sand conveying channel; 21. a lower roll; 22. upper roll; 23. a carrier tape; 231. a blanking hole; 232. damping the stripes; 2321. twill; 2322. straight lines; 24. a shaping wheel; 25. a tension roller; 26. a material placing area; 27. a transfer plate; 28. mounting grooves; 29. a material guide chute; 31. a rotating shaft; 32. a second power assembly; 321. a drive plate; 322. a second motor; 323. a second primary rocker arm; 324. a second sub-rocker arm; 325. a transmission rod; 326. swinging arms; 327. an adapter; 33. placing a frame; 34. a spray head; 35. a sand conveying pipe; 351. an inner tube; 352. cutting; 353. a second filter screen; 354. pressing sheets; 355. a compensation hole; 36. a pneumatic tube; 37. and (4) branch pipes.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

Example 1: a sand blasting machine is shown in figures 1 and 2 and comprises a machine shell 1, a material loading mechanism 2 arranged in a working cavity 11 and a sand blasting mechanism 3 with a spray head 34 arranged in the working cavity 11, wherein the machine shell 1 is internally provided with the working cavity 11 positioned above and a sand storage cavity 12 positioned below.

Referring to fig. 3, two air curtain outlets 13 respectively separated from two sides of the nozzle 34 and inclined downward toward the nozzle 34 are disposed on the inner wall of the working chamber 11, and a fan for supplying air to the air curtain outlets 13 is disposed on the casing 1.

Referring to fig. 2 and 3, the loading mechanism 2 includes a lower roller 21, an upper roller 22, a bearing belt 23 wound around the lower roller 21 and the upper roller 22, a shaping wheel 24 disposed between the upper roller 22 and the lower roller 21, a first power assembly driving the upper roller 22 to rotate, and a tension roller 25. Wherein the first power assembly is a first motor, and the first motor drives the upper roller 22 to rotate in a toothed belt transmission mode. The number of the shaping wheels 24 is at least two, and the shaping wheels are respectively close to two sides of the carrier belt 23, the outer side surface of the carrier belt 23 is wound on the circumferential surface of the shaping wheels 24, a material placing area 26 for placing a workpiece is formed, and the spray head 34 of the sand blasting mechanism 3 faces the material placing area 26. The surface of the carrier band 23 is hollowed to form a plurality of blanking holes 231 for the sand to pass through, and a plurality of groups of damping stripes 232 are arranged in a protruding manner along the length direction. Referring to fig. 4, the damping stripe 232 includes two splayed twills 2321 and straight stripes 2322 spaced from the twills 2321 along the length direction of the carrier tape 23. The opening direction of the two twills 2321 faces the direction in which the carrier tape 23 revolves. Referring to fig. 2 and 3, the tension roller 25 is located below the shaping wheel 24, and the tension roller 25 presses against the inside surface of the underlying carrier belt 23. A transfer plate 27 for collecting the sand leaked from the blanking hole 231 is arranged between the tension roller 25 and the bearing belt 23 above the tension roller 25, and an installation groove 28 for obliquely embedding the transfer plate 27 and a guide chute 29 for connecting the installation groove 28 and the sand storage cavity are arranged on the inner wall of the machine shell 1.

Referring to fig. 4 and 5, the sand blasting mechanism 3 includes a rotating shaft 31 penetrating through the working chamber 11, a second power assembly 32 driving the rotating shaft 31 to rotate, a swing frame 33 fixed on the rotating shaft 31, and at least two nozzles 34 arranged on the swing frame 33 along the width direction of the carrier tape 23, the rotating shaft 31 is rotatably connected to the housing 1, the nozzles 34 face the material placing area 26, and the tail of the nozzles are connected with a sand feeding pipe 35 and a pneumatic pipe 36, and the swing frame 33 swings back and forth along the conveying direction of the carrier tape 23.

Referring to fig. 5 and 6, an inner pipe 351 is fixed to an inner wall of the sand feeding pipe 35, and a branch pipe 37 penetrating the sand feeding pipe 35 and supplying gas to the inner pipe 351 is connected to the inner pipe 351. Referring to fig. 6 and 7, the inner tube 351 is provided with a plurality of notches 352 having openings facing the inner cavity of the sand feed pipe 35, the notches 352 having a V-shape extending to the center of the inner tube 351 and being distributed along the longitudinal direction of the inner tube 351, and a second screen 353 is provided at the openings. A pressure-changing sheet 354 is fixed in the middle of each cut 352, the diameter of the pressure-changing sheet 354 is the same as the inner diameter of the inner tube 351, and a compensation hole 355 communicated with the inner pipeline of the inner tube 351 is formed in the center of the pressure-changing sheet 354. The diameter of the compensation hole 355 is one third to one half of the diameter of the pressure-transforming plate 354. The branch pipe 37 and the pneumatic pipe 36 are connected to an air compressor installed outside the cabinet 1.

Referring to fig. 4 and 8, the second power assembly 32 includes a driving plate 321 whose axis is parallel to the rotation shaft 31, a second motor 322 driving the driving plate 321 to rotate, a second main swing arm 323 fixed to the driving plate 321, a swing arm 326 hinged to one end of the second main swing arm 323, a second sub swing arm 324 fixed to the rotation shaft 31, and a driving rod 325 connected to the housing 1 in a sliding manner along the length direction; two ends of the transmission rod 325 are respectively hinged with the swing arm 326 and the second sub-swing arm 324, wherein an adapter 327 is fixed at one end connected with the second sub-swing arm 324, and the adapter 327 is connected to the second sub-swing arm 324 in a sliding manner along the length direction of the second sub-swing arm 324.

Referring to fig. 1 and 2, a feeding port 14 for feeding in and out a workpiece is formed in one side of the machine shell 1, the lower roller 21 is close to the feeding port 14, the lower roller 21 is located below the feeding port 14 in height, and a gate 15 is arranged at the opening of the feeding port 14. A feed hopper 16 communicated to the sand storage cavity 12 is arranged outside the feed port 14 of the shell 1, and a first filter screen 17 for blocking workpieces is arranged on the feed hopper 16. The side wall of the machine shell 1 is provided with a sand conveying channel 18 communicated to the sand storage cavity 12 and a sand conveying machine arranged in the sand conveying channel 18 and used for conveying sand to the top of the machine shell 1.

The use method comprises the following steps:

introducing the workpiece into the material placing area 26 through the material feeding port 14, closing the machine door 15, and starting the sand blasting machine; at this time, the upper roller 22 is driven by the first motor to drive the carrying belt 23 to rotate, and simultaneously, the second motor 322 rotates to drive the second main rocker 323 to rotate, and the swing arm 326 drives the transmission rod 325 limited to only slide to linearly reciprocate, so as to drive the rotating shaft 31 to reciprocate, thereby realizing the small-amplitude swing of the spray head 34. In the sand blasting process, the sand on the surface of the carrier belt 23 falls into the transfer plate 27 through the blanking holes 231 and falls into the sand storage cavity 12 along the surface guide of the transfer plate 27, and the sand in the sand storage cavity 12 is driven by the sand conveying machine and enters the spray head 34 again through the sand conveying channel 18 and the sand conveying pipe 35.

After the sand blasting is finished, the workpieces are taken out in a centralized mode and placed on a first filter screen 17 of the feed hopper 16, redundant sand materials enter the sand storage cavity 12 through the feed hopper 16, and the workpieces can be moved out.

In addition, can also realize sand material replenishment through adding sand material to the feeder hopper.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the present invention.

Claims

1. A sand blasting machine comprises a machine shell (1) with a working cavity (11), and is characterized in that: a lower roller (21), an upper roller (22), a bearing belt (23) wound on the lower roller (21) and the upper roller (22), a shaping wheel (24) arranged between the upper roller (22) and the lower roller (21), and a first power assembly driving the upper roller (22) to rotate are arranged in the working cavity (11); wherein, the number of the shaping wheels (24) is at least two and the shaping wheels are respectively close to the two sides of the bearing belt (23); the outer side surface of the bearing belt (23) is wound on the circumferential surface of the shaping wheel (24) and forms a material placing area (26) for placing a workpiece; a plurality of blanking holes (231) for sand to pass through are hollowed in the surface of the bearing belt (23); a sand blasting mechanism (3) with a spray head (34) facing the material placing area (26) is arranged above the material placing area (26), a plurality of groups of damping stripes (232) protruding out of the surface of the carrier tape are distributed on the carrier tape (23) along the length direction, and each damping stripe (232) comprises two splayed twills (2321) and straight stripes (2322) arranged at intervals with the twills (2321) along the length direction of the carrier tape (23); the opening directions of the two twills (2321) face the revolving direction of the carrier belt (23); a feeding port (14) for a workpiece to enter and exit is formed in one side of the machine shell (1), the lower roller (21) is close to the feeding port (14), and the lower roller (21) is located below the feeding port (14) in height; a sand storage cavity (12) is arranged below the working cavity (11), a feed hopper (16) communicated with the sand storage cavity (12) is arranged on the outer side of the feeding port (14) of the shell (1), and a first filter screen (17) for blocking a workpiece is arranged on the feed hopper (16); a tensioning roller (25) abutted to the inner side of the bearing belt (23) is arranged below the shaping wheel (24), the tensioning roller (25) is located at the lower side of the lower roller (21) in height, a transfer plate (27) for collecting sand leaking from the blanking hole (231) is arranged between the tensioning roller (25) and the bearing belt (23) above the tensioning roller (25), the area of the transfer plate (27) located at the lower side of the shaping wheel (24) is a concave arc surface, the surface height of the transfer plate (27) on two sides based on the arc surface is gradually increased, and a mounting groove (28) for obliquely embedding the transfer plate (27) and a guide groove (29) for connecting the mounting groove (28) and the sand storage cavity are arranged on the inner wall of the machine shell (1); the side wall of the machine shell (1) is provided with a sand conveying channel (18) communicated to the sand storage cavity and a sand conveying machine arranged in the sand conveying channel (18) and used for conveying sand materials to the top of the machine shell (1).

2. A blasting machine as claimed in claim 1, wherein: sandblast mechanism (3) including wear to locate pivot (31) of working chamber (11), drive pivot (31) pivoted second power component (32), be fixed in swing span (33) and at least two along bearing width direction row cloth in swing span (33) of taking (23) in pivot (31), pivot (31) rotate to be connected in casing (1), material district (26) and end connection are put to shower nozzle (34) orientation have sand sending pipe (35) and atmospheric pressure pipe (36), swing span (33) are along the direction of delivery swing back and forth that bears area (23).

3. A blasting machine as claimed in claim 2, wherein: the second power assembly (32) comprises a transmission disc (321) with the axis parallel to the rotating shaft (31), a second motor (322) for driving the transmission disc (321) to rotate, a second main rocker arm (323) fixed on the transmission disc (321), a swing arm (326) hinged to one end of the second main rocker arm (323), a second sub rocker arm (324) fixed on the rotating shaft (31) and a transmission rod (325) connected to the machine shell (1) in a sliding manner along the length direction; the both ends of transfer line (325) are articulated with swing arm (326) and second sub-rocking arm (324) respectively, and wherein be fixed with adapter (327) with the one end of being connected of second sub-rocking arm (324), adapter (327) slide along the length direction of second sub-rocking arm (324) and connect in second sub-rocking arm (324).

4. A blasting machine as claimed in claim 2, wherein: an inner pipe (351) is fixed on the inner wall of the sand conveying pipe (35), a branch pipe (37) which penetrates through the sand conveying pipe (35) and conveys gas to the inner pipe (351) is arranged on the inner pipe (351) in a communicating mode, a notch (352) with an opening facing to the inner cavity of the sand conveying pipe (35) is formed in the inner pipe (351), and a plurality of notches (352) are distributed along the length direction of the inner pipe (351).

5. A blasting machine as claimed in claim 4, wherein: a pressure varying sheet (354) is fixed in the middle of each cut (352), the diameter of each pressure varying sheet (354) is the same as the inner diameter of the inner pipe (351), a compensation hole (355) communicated with the inner pipe of the inner pipe (351) is formed in the center of each pressure varying sheet (354), and each cut (352) is V-shaped and extends to the center of the inner pipe (351).

6. A blasting machine as claimed in claim 5, wherein: a second filter screen (353) is arranged at the opening of the cut (352), and the diameter of the compensation hole (355) is one third to one half of the diameter of the variable pressure sheet (354).

7. A blasting machine as claimed in claim 1, wherein: the inner wall of the working cavity (11) is provided with two air curtain air outlets (13) which are respectively separated from two sides of the spray head (34) and incline downwards towards the spray head (34), and the casing (1) is provided with fans which respectively supply air to the air curtain air outlets (13).