CN116481278A - A composite tumble dryer for pet food in an ultra-low pressure environment - Google Patents

Abstract

The invention relates to the technical field of pet food drying, in particular to a composite turning dryer for pet food in an ultralow pressure environment, which is more uniform in drying of the pet food, high in drying efficiency and good in drying effect; the drying box is arranged on the bottom plate, a drying cavity is arranged in the drying box, a taking and placing opening communicated with the drying cavity is formed in the drying box, and the sealing door is arranged on the outer side of the taking and placing opening; the air circulation device comprises a cylinder, an air ejector, a ball head, a supporting seat, a hose, an air heater, a plurality of groups of arc blocks, a supporting device, a rotating device, an air circulation device and a vacuum device, wherein a cavity is formed in the cylinder, a plurality of groups of air holes communicated with the cavity are formed in the cylinder, the cylinder is fixedly arranged on the air ejector, the upper part of the air ejector is positioned in the cavity of the cylinder, a plurality of groups of air exhaust holes are formed in the upper part of the air ejector, the ball head is fixedly arranged on the lower part of the air ejector, and the supporting seat is fixedly arranged on the supporting device.

Description

A composite tumble dryer for pet food in an ultra-low pressure environment

technical field

The invention relates to the technical field of pet food drying, in particular to a compound tumble dryer for pet food in an ultra-low pressure environment.

Background technique

Pet food is a kind of food used to feed pets. Artificial pet food is mostly granular. During its production, rice grains and vegetables are first crushed into powder, and then a certain proportion of food additives are added to mix and stir. After adding water and mixed, they are made into pellets by a pellet machine, and are preliminarily dried in the pellet machine to remove most of the water.

In the prior art, most pet food dryers with patent application numbers of "202220872214.8", "202220033169.7" and "202111183042.X" generally adopt the technical method of first placing the pet food on the carrier plate, and then blowing hot air on the pet food to achieve the purpose of promoting the drying of the pet food. However, the pet food cannot be moved while blowing the hot air. The hot air on the side close to the carrying plate is less, resulting in uneven drying of pet food and poor drying effect, so a dryer that can evenly dry pet food is needed.

Contents of the invention

In order to solve the above-mentioned technical problems, the present invention provides a compound tumble dryer that can dry pet food more uniformly, with high drying efficiency and good drying effect under ultra-low pressure environment.

A compound tumble dryer for pet food in an ultra-low pressure environment of the present invention comprises a bottom plate, a drying box and a sealing door. The drying box is installed on the bottom plate. A drying chamber is arranged inside the drying box. A pick-and-place opening connected to the drying chamber is arranged on the drying box. The cylinder is fixedly installed on the air jet pipe, the upper part of the air jet pipe is located in the chamber of the cylinder, the upper part of the air jet pipe is provided with multiple sets of exhaust holes, the ball head is fixedly installed at the lower part of the air jet pipe, the support seat is fixedly installed on the support device, the support device is installed in the drying oven, the support device is used to support the support seat, the support seat is provided with a spherical groove for use with the ball head, and the lower part of the ball head is located in the spherical groove of the support seat. The circulation device is installed on the drying box, the air circulation device is used for drying and transporting air, the upper part of the cylinder is installed on the rotating device, and the rotating device is used to reciprocate the rotating cylinder. There are multiple groups of arc-shaped blocks fixedly installed inside the cylinder, and the vacuum device is installed on the drying box. Then turn on the hot air blower, let the hot air blower output hot air into the hose, and then the hot air enters the jet pipe through the hose, and then the hot air in the jet pipe blows to the pellet-shaped pet food in the chamber of the jet pipe through multiple sets of exhaust holes on the upper part of the jet pipe, and at the same time, turn on the rotating device, which makes the cylinder reciprocate periodically, and the cylinder drives the pet food during the reciprocating rotation. The hot air is blown to dry, and due to the function of multiple sets of arc-shaped blocks, the pet food will be blocked by multiple sets of arc-shaped blocks when it moves in the cylinder, which further promotes the effect of tumbling movement of the pet food, so that the pet food can be blown to dry evenly by the hot air, so that the moisture in the pet food and the hot air are discharged through multiple sets of exhaust holes on the cylinder, and then the air circulation device is turned on, so that the hot air with moisture is dried by the air circulation device and then enters the hot air blower for recycling; The inside is a low-pressure environment, which makes the moisture in the pet food easy to evaporate, which promotes the drying of the pet food, and when the pet food is dried, the pet food can be continuously rolled and moved, and the hot air can be evenly blown to all parts of the pet food, and the drying is uniform and the drying effect is good.

Preferably, the support device includes a support plate, two sets of springs, two sets of fixing plates, two sets of rollers, two sets of support wheels, two sets of drive shafts and a biaxial motor. The support plate slides up and down and is installed on the drying box. The two sets of support wheels are fixedly installed on the two sets of drive shafts respectively, the two sets of support wheels are eccentrically connected with the two sets of drive shafts, the two sets of drive shafts are coaxial, two sets of support plates are arranged on the drying box, the support plates are fixedly installed on the dry box, the two sets of drive shafts are respectively rotatably mounted on the two sets of support plates, the input ends of the two sets of drive shafts are respectively connected with the two sets of output ends of the double-axis motor, the double-axis motor is fixedly installed on the dry box, the two sets of springs are in a stretched state, the support plate is provided with a sliding track, and the lower part of the support seat is slidingly installed in the slide track of the support plate; When pet food is drying, turn on the double-axis motor, the double-axis motor drives the two sets of drive shafts to rotate, and the two sets of drive shafts drive the two sets of support wheels to rotate. Since the two sets of drive shafts and the two sets of support wheels are eccentrically connected, the two sets of support wheels will move up and down while rotating. The two sets of support wheels drive the two sets of fixed plates to vibrate the support plate up and down. Drying improves the drying effect on pet food.

Preferably, the air circulation device includes a delivery pipe, an air pump, a drier and a return pipe, the hot air blower is installed on the drying box, the input end of the delivery pipe is connected to the upper part of the drying box chamber, the output end of the delivery pipe is connected to the drier through an air pump, the output end of the drier is connected to the hot air blower through a return pipe, a desiccant is arranged in the drier, and the air pump and the drier are fixedly installed on the drying box; Dry in the dryer, and then the dried hot air can be recycled through the dryer into the hot air blower; it makes the hot air can be recycled, saving heat and energy.

Preferably, the rotating device includes a rotating shaft, a gear, a rack, two sets of sliding blocks, slide rails, a connecting block, a universal joint, a connecting shaft, a reciprocating screw, a support block and a driving motor; The lead screw is screw-mounted, and the reciprocating lead screw is installed on two sets of support blocks. The two sets of support blocks are fixedly installed on the upper end of the drying box. The right end of the reciprocating lead screw is connected to the output end of the drive motor. The reciprocating screw rotates, because the reciprocating screw and the connecting block are screwed together, so the rotating reciprocating screw drives the connecting block to reciprocate left and right, and the connecting block drives the rack to reciprocate left and right. Because the gear and the rack are meshed, the rack makes the gear reciprocate periodically during the left and right reciprocating motion, and the gear drives the rotating shaft to reciprocate periodically. When the device makes the support base drive the ball head and the air jet tube to vibrate up and down, the air jet tube drives the cylinder to vibrate up and down at the same time. Due to the vertical vibration of the cylinder and the support base slides and is installed in the sliding track of the support plate, the support base will slide in the slide track of the support plate.

Preferably, the vacuum device is a vacuum pump, the vacuum pump is installed on the drying box, the input end of the vacuum pump communicates with the drying chamber of the drying box, and the vacuum pump is provided with a valve; when drying the pet food, first turn on the vacuum pump, so that the drying chamber of the drying box is in a low-pressure environment, and then close the valve on the vacuum pump, so that the pet food can be dried in a low-pressure environment, so that the food can be quickly dried at a lower temperature, without using hot air at a higher temperature, avoiding the damage caused by the hot air at a higher temperature to the protein or other nutrients in the pet food , high reliability.

Preferably, it also includes two groups of microwave generators, both groups of microwave generators are installed on the upper part of the drying chamber of the drying box, and the output ends of the two groups of microwave generators all rush to the cylinder; when the pet food is dried, the two groups of microwave generators are turned on at the same time, so that the microwaves emitted by the two groups of microwave generators are transmitted to the pet food, so that the water in the pet food is heated up, and the evaporation of water is promoted, and the drying efficiency is improved.

Preferably, the cylinder is made of high-temperature-resistant glass; through the above-mentioned settings, its high-temperature resistance effect is improved and reliability is ensured, and it is made of glass, so that microwaves can easily penetrate the cylinder to dry pet food, reduce the absorption and blocking of microwaves by the cylinder, improve the utilization rate of microwaves, and have high practicability.

Preferably, the drying box is provided with a thermometer; through the above arrangement, it is convenient to monitor the temperature in the drying chamber of the drying box.

Preferably, the drying box is provided with an air pressure gauge; through the above arrangement, the monitoring of the air pressure in the drying chamber of the drying box is facilitated.

Preferably, the shape of the sliding track is circular.

Preferably, the shape of the sliding track is ellipse.

Compared with the prior art, the present invention has the beneficial effects of drying the pet food more uniformly, with high drying efficiency and good drying effect.

Description of drawings

Fig. 1 is the sectional structure schematic diagram of the present invention;

Fig. 2 is the structural representation of support device;

Fig. 3 is the structural representation of air circulation device;

Fig. 4 is the structural representation of cylinder and rotating device;

Fig. 5 is a partially enlarged schematic structural view of place B in Fig. 4;

Fig. 6 is the structural representation of ball head, jet pipe and flexible pipe etc.;

Fig. 7 is a structural schematic diagram of a support seat;

Fig. 8 is the structural representation of the jet pipe of cylinder;

Fig. 9 is a schematic diagram of an axonometric structure of the present invention;

Fig. 10 is a schematic diagram of the front view structure of the present invention;

Fig. 11 is the structural representation of support plate in embodiment 1;

Fig. 12 is a schematic structural view of a support plate in Embodiment 2;

Marks in the accompanying drawings: 1, bottom plate; 2, drying oven; 3, sealed door; 4, cylinder; 5, jet pipe; 6, ball head; 7, support seat; 8, hose; 9, hot air blower; 10, arc block; 11, support plate; 12, spring; 13, fixed plate; 14, roller; 15, support wheel; 16, drive shaft; 17, double-axis motor; 18, delivery pipe; Tube; 22, rotating shaft; 23, gear; 24, rack; 25, sliding block; 26, slide rail; 27, connecting block; 28, universal joint; 29, connecting shaft; 30, vacuum pump; 31, microwave generator; 32, reciprocating lead screw; 33, supporting block; 34, driving motor.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the associated drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

Example 1

As shown in Fig. 1 to Fig. 12, the composite turning dryer for pet food in an ultra-low pressure environment of the present invention comprises a bottom plate 1, a drying box 2, a sealing door 3, a cylinder 4, an air jet pipe 5, a ball head 6, a support seat 7, a hose 8, a hot air blower 9, multiple groups of arc blocks 10, a supporting device, a rotating device, an air circulation device, a vacuum pump 30, and two groups of microwave generators 31. The drying box 2 is installed on the bottom plate 1. The airtight door 3 is installed on the outside of the pick-and-place port, the inside of the cylinder 4 is provided with a chamber, and the cylinder 4 is provided with multiple groups of air holes communicating with the chamber. The cylinder 4 is fixedly installed on the air jet pipe 5. There is a spherical groove used in conjunction with the ball head 6. The lower part of the ball head 6 is located in the spherical groove of the support seat 7. The input end of the air injection pipe 5 is connected to the output end of the hot air blower 9 through a hose 8. The air circulation device is installed on the drying box 2. The air circulation device is used for drying and conveying air. The upper part of the cylinder 4 is installed on the rotating device. The drying cavity of the box 2 is connected, the vacuum pump 30 is provided with a valve, and two groups of microwave generators 31 are installed on the top of the drying cavity of the drying box 2, and the output ends of the two groups of microwave generators 31 are all rushed to the cylinder 4, and the material of the cylinder 4 is high-temperature-resistant glass material. The drying box 2 is provided with a thermometer, and the drying box 2 is provided with an air pressure gauge;

Firstly open the airtight door 3, then put the preliminarily dried pellet-shaped pet food into the cylinder 4 through the feeding port on the cylinder 4, then close the airtight cover on the cylinder 4, then close the airtight door 3, then turn on the vacuum pump 30 to make the drying chamber of the drying box 2 a low-pressure environment, then close the valve on the vacuum pump 30 to keep the pet food in a low-pressure environment, then turn on the hot air blower 9 to output hot air from the hot air blower 9 to the hose 8, then the hot air enters the air injection pipe 5 through the hose 8, and then the air injection pipe The hot air in 5 is blown onto the pellet-shaped pet food in the chamber of the air-jet pipe 5 through multiple groups of exhaust holes on the upper part of the air-jet pipe 5. At the same time, two groups of microwave generators 31 are turned on, so that the microwaves emitted by the two groups of microwave generators 31 are transmitted to the pet food, and the moisture in the pet food is heated up. At the same time, the rotating device is turned on, which makes the cylinder 4 reciprocate periodically. The pet food in the cylinder 4 can be evenly blown to dry by the hot air, and it can evenly receive the microwave, and due to the action of multiple sets of arc-shaped blocks 10, the pet food will be blocked by multiple sets of arc-shaped blocks 10 when moving in the cylinder 4, which further promotes the effect of the tumbling movement of the pet food, so that the pet food can be evenly blown to dry by the hot air, so that the moisture in the pet food and the hot air are exhausted through multiple sets of exhaust holes on the cylinder 4, and then the air circulation device is turned on to make the hot air with moisture dry through the air circulation device Afterwards, it can be recycled in the hot air blower 9 for the second time; when drying the pet food, the drying chamber of the drying box 2 is a low-pressure environment, so that the moisture in the pet food is easy to evaporate, which promotes the drying of the pet food, and when the pet food is dried, the pet food can be continuously rolled and moved, and the hot air can be evenly blown to various parts of the pet food, and the drying is uniform and the drying effect is good.

As shown in Fig. 2 and Fig. 11, the support device comprises a support plate 11, two groups of springs 12, two groups of fixed plates 13, two groups of rollers 14, two groups of support wheels 15, two groups of drive shafts 16 and a biaxial motor 17, the support plate 11 slides up and down and is mounted on the drying box 2, the lower ends of the two groups of springs 12 are fixedly installed on the drying box 2, the upper ends of the two groups of springs 12 are fixedly connected with the lower ends of the supporting plates 11, the support base 7 is fixedly installed on the upper ends of the supporting plates 11, and the two groups of fixing plates 13 are respectively fixedly mounted on the supporting plates 1 The left and right parts of the lower end of 1, two groups of rollers 14 are respectively rotatably mounted on two groups of fixing plates 13, the lower parts of the two groups of rollers 14 are respectively in contact with the upper parts of two groups of support wheels 15, and the two groups of support wheels 15 are respectively fixedly mounted on two groups of drive shafts 16, the two groups of support wheels 15 are eccentrically connected with the two groups of drive shafts 16, the two groups of drive shafts 16 are coaxial, the drying box 2 is provided with two groups of supporting plates, and the supporting plates are fixedly installed on the drying box 2, and the two groups of driving shafts 16 are respectively rotatably mounted on the two groups of supporting plates, and the two groups of driving shafts 16 The input end of each is connected with two groups of output ends of biaxial motor 17, and biaxial motor 17 is fixedly installed on the drying box 2, and two groups of springs 12 are stretched state, and support plate 11 is provided with slide track, and the bottom of support base 7 is slidably installed in the slide track of support plate 11, and the shape of slide track is circular;

When drying the pet food in the cylinder 4 chamber, turn on the biaxial motor 17, the biaxial motor 17 drives two groups of drive shafts 16 to rotate, and the two groups of drive shafts 16 drive the two groups of support wheels 15 to rotate. Since the two groups of drive shafts 16 and the two groups of support wheels 15 are connected eccentrically, the two groups of support wheels 15 will move up and down while rotating. , the support wheel 15 drives the cylinder 4 to vibrate up and down, and the cylinder 4 further promotes the tumbling effect of the pet food in the chamber of the cylinder 4 during the up and down vibration, so that the pet food can be dried evenly, and the drying effect on the pet food is improved.

As shown in Fig. 4 and Fig. 5, the rotating device includes a rotating shaft 22, a gear 23, a rack 24, two groups of sliding blocks 25, a slide rail 26, a connecting block 27, a universal joint 28, a connecting shaft 29, a reciprocating screw 32, a supporting block 33 and a drive motor 34, the rotating shaft 22 is installed on the top of the drying box 2, the gear 23 is fixedly installed on the upper end of the rotating shaft 22, the rear portion of the gear 23 is engaged with the rack 24, and the rack 24 is fixedly installed on the two groups of sliding blocks 25. Two groups of sliding blocks 25 are all slidably installed on the slide rail 26 left and right, the slide rail 26 is fixedly mounted on the upper end of the drying box 2, the connecting block 27 is fixedly mounted on the lower end of the rack 24, the connecting block 27 is screwed with the reciprocating screw 32, the reciprocating screw 32 is rotated and installed on the two sets of support blocks 33, and the two sets of support blocks 33 are all fixedly installed on the upper end of the drying box 2. The sliding blocks 25 are all provided with avoidance holes, and the reciprocating lead screw 32 runs through the avoiding holes on the two sets of sliding blocks 25, the two sets of sliding blocks 25 do not contact the reciprocating lead screws 32, the lower end of the rotating shaft 22 is connected with the upper end of the connecting shaft 29 through a universal joint 28, and the lower end of the connecting shaft 29 is fixedly installed on the upper end of the cylinder 4;

When the cylinder 4 is rotated, the drive motor 34 is turned on, and the drive motor 34 drives the reciprocating lead screw 32 to rotate. Since the reciprocating lead screw 32 is screwed to the connecting block 27, the reciprocating lead screw 32 drives the connecting block 27 to reciprocate left and right, and the connecting block 27 drives the rack 24 to reciprocate left and right. Reciprocating rotation, rotating shaft 22 makes connecting shaft 29 drive cylinder 4 to periodically reciprocate through universal joint 28, so that the pet food in the chamber of cylinder 4 is continuously rolled under the action of inertial force, and at the same time, when the support seat 7 drives the ball head 6 and air injection pipe 5 to vibrate up and down through the supporting device, the air injection pipe 5 simultaneously drives the cylinder 4 to vibrate up and down. , the support seat 7 makes the air jet pipe 5 drive the lower part of the cylinder 4 to move through the ball head 6, so the cylinder 4 will also swing back and forth while rotating, which further promotes the tumbling effect of the pet food in the chamber of the cylinder 4, making it more evenly dried.

The drying box 2 is provided with a thermometer, and the drying box 2 is provided with an air pressure gauge.

Example 2

On the basis of Embodiment 1, multiple groups of hanging hooks are added on the outer wall of the cylinder 4 . For some large carnivorous pets, it sometimes needs to make jerky. Meat is hung on the hook on the cylinder 4 outer sidewall this moment, makes meat be contacted with microwave on the cylinder 4 outer sidewall and gets final product. You can choose to install it according to whether the customer has the need to make large pieces of jerky.

As shown in Figure 12, the shape of the sliding track on the support plate 11 is elliptical, so that the lower part of the supporting seat 7 slides in the elliptical sliding track during motion. Different sliding tracks can make the supporting seat 7 slide on different tracks.

In summary, the main beneficial effects of the present invention are:

1. By swinging, rotating and vibrating up and down the cylinder 4, the pellet-shaped pet food in the chamber of the cylinder 4 can be continuously rolled and moved, so that it can be evenly contacted with hot air and microwaves, and the drying is uniform and the drying effect is good.

2. The pet food is dried under low pressure environment, and the drying effect can be guaranteed at a lower temperature, which avoids high temperature damage to the nutrients in the pet food, and has high reliability.

3. The hot air used in the drying process can be recycled, which saves resources and conforms to the current concept of energy saving and environmental protection.

4. By adopting different shapes of sliding tracks on the support plate 11, the cylinder 4 can be swayed in different ways, and it is sufficient to select a suitable sliding track according to the shape and size of the pet feed.

What needs to be added is: 1. The cylinder 4 is provided with a feed port and a discharge port communicating with the chamber, and a detachable sealing cover is provided outside the feed port and the discharge port.

2. The surface of the ball head 6 is a smooth surface, and the interior of the spherical groove on the upper part of the support seat 7 is a smooth surface, and the friction between the ball head 6 and the spherical groove is small.

3. The support seat 7 is assembled by two sets of mirrored connecting blocks. When it is installed with the ball head 6, the two sets of connecting blocks are covered on the outside of the ball head 6, and then the two sets of connecting blocks are fixedly connected with bolts.

4. The desiccant in the desiccant 20 is a recyclable desiccant. When the desiccant is saturated, it can be dehydrated and put into the desiccant 20 for recycling.

5. The biaxial motor 17 has an angle self-locking function.

The drying box 2, ball head 6, hot air blower 9, spring 12, biaxial motor 17, air pump 19, dryer 20, rack 24, universal joint 28, vacuum pump 30, microwave generator 31, reciprocating lead screw 32 and drive motor 34 of the composite tumbling dryer for pet food in an ultra-low pressure environment of the present invention are purchased from the market, and technical personnel in the industry only need to install and operate according to the accompanying instruction manual, without creative work by those skilled in the art.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be considered as protection scope of the present invention.

Claims (10)

1. A composite tumble dryer for pet food in an ultra-low pressure environment, comprising a base plate (1), a drying box (2) and a sealing door (3), the drying box (2) being installed on the base plate (1), a drying chamber being arranged inside the drying box (2), a pick-and-place opening connected to the drying chamber being provided on the drying box (2), and a sealing door (3) being installed on the outside of the pick-and-place mouth; it is characterized in that it also includes a cylinder (4), an air jet pipe (5), a ball head (6), a support seat (7), Hose (8), hot air blower (9), multiple groups of arc-shaped blocks (10), supporting device, rotating device, air circulation device and vacuum device; the inside of the cylinder (4) is provided with a chamber, and the cylinder (4) is provided with multiple groups of ventilation holes communicating with the chamber; the cylinder (4) is fixedly installed on the air injection pipe (5); The lower part of the air pipe (5), the support seat (7) is fixedly installed on the support device, the support device is installed in the drying box (2), the support device is used to support the support seat (7), and the support seat (7) is provided with a spherical groove for use with the ball head (6). Dry and transport air, the upper part of the cylinder (4) is installed on the rotating device, the rotating device is used to reciprocally rotate the cylinder (4), the interior of the cylinder (4) is fixedly installed with multiple groups of arc blocks (10), the vacuum device is installed on the drying box (2), and the vacuum device is used to provide a low pressure environment. 2. The composite tumble dryer for pet food in an ultra-low pressure environment as claimed in claim 1, wherein the support device comprises a support plate (11), two sets of springs (12), two sets of fixed plates (13), two sets of rollers (14), two sets of support wheels (15), two sets of drive shafts (16) and a double-axis motor (17), the support plate (11) slides up and down and is installed on the drying box (2), and the lower ends of the two sets of springs (12) are all fixedly installed on the drying box (2). The upper ends of the two groups of springs (12) are fixedly connected with the lower ends of the support plates (11), the support seats (7) are fixedly mounted on the upper ends of the support plates (11), the two groups of fixed plates (13) are respectively fixedly installed on the left and right parts of the lower end of the support plates (11), the two groups of rollers (14) are respectively rotated and installed on the two groups of fixed plates (13), the bottoms of the two groups of rollers (14) contact the upper parts of the two groups of support wheels (15) respectively, and the two groups of support wheels (15) are respectively fixedly installed on the two groups of drive shafts (1 6), the two sets of support wheels (15) are eccentrically connected to the two sets of drive shafts (16), the two sets of drive shafts (16) are coaxial, two sets of support plates are arranged on the drying box (2), the support plates are fixedly mounted on the drying box (2), the two sets of drive shafts (16) are respectively rotatably mounted on the two sets of support plates, the input ends of the two sets of drive shafts (16) are respectively connected to the two sets of output ends of the double-axis motor (17), and the double-axis motor (17) is fixedly installed on the dry box (2), and the two sets of springs (12) are In the stretched state, the support plate (11) is provided with a slide track, and the bottom of the support seat (7) is slidably installed in the slide track of the support plate (11). 3. the compound stirring drier under a kind of pet food ultra-low pressure environment as claimed in claim 1, it is characterized in that, described air circulation device comprises delivery pipe (18), air pump (19), dryer (20) and return pipe (21), hot air blower (9) is installed on the drying box (2), the input end of delivery pipe (18) is connected with the top of drying box (2) chamber, the output end of delivery pipe (18) is connected with dryer (20) by air pump (19), The output end of the drier (20) is connected with the hot air blower (9) through the return pipe (21), the drier (20) is provided with desiccant, and the air pump (19) and the drier (20) are all fixedly installed on the drying box (2). 4. The composite tumble dryer for pet food in an ultra-low pressure environment as claimed in claim 1, wherein the rotating device includes a rotating shaft (22), a gear (23), a rack (24), two sets of sliding blocks (25), a slide rail (26), a connecting block (27), a universal joint (28), a connecting shaft (29), a reciprocating screw (32), a support block (33) and a drive motor (34), and the rotating shaft (22) is installed in a drying box (2), the gear (23) is fixedly installed on the upper end of the rotating shaft (22), and the rear portion of the gear (23) meshes with the rack (24). The reciprocating leading screw (32) is screw-mounted, and the reciprocating leading screw (32) is rotatably installed on two groups of support blocks (33). Avoidance hole, the lower end of rotating shaft (22) is connected with the upper end of connecting shaft (29) by universal joint (28), and the lower end of connecting shaft (29) is fixedly installed in cylinder (4) upper end. 5. The compound tumble drier under the ultra-low pressure environment of a kind of pet food as claimed in claim 1, it is characterized in that, described vacuum device is vacuum pump (30), and vacuum pump (30) is installed on the drying box (2), and the input end of vacuum pump (30) is communicated with the drying cavity of drying box (2), and valve is provided on the vacuum pump (30). 6. The compound tumble drier under the ultra-low pressure environment of a kind of pet food as claimed in claim 1, is characterized in that, also comprises two groups of microwave generators (31), and two groups of microwave generators (31) are all installed on the top of drying box (2) drying cavity, and the output ends of two groups of microwave generators (31) all rush toward cylinder (4). 7. The composite tumble dryer for pet food in an ultra-low pressure environment according to claim 1, characterized in that, the cylinder (4) is made of high temperature resistant glass. 8. The compound tumble dryer for pet food in an ultra-low pressure environment as claimed in claim 1, wherein a thermometer is arranged on the drying box (2); an air pressure gauge is arranged on the drying box (2). 9. The compound tumble dryer for pet food in an ultra-low pressure environment according to claim 2, wherein the shape of the sliding track is circular. 10 . The compound tumble dryer for pet food in an ultra-low pressure environment according to claim 2 , wherein the shape of the sliding track is ellipse. 11 .