CN117160647A - An efficient crushing system for limestone - Google Patents

Abstract

The invention discloses an efficient crushing system for limestone, which includes a base. A feed hopper is installed on the top of the base. A fixed cylinder is installed on the bottom of the feed hopper. A rotating column is installed on the inside of the fixed cylinder. The rotating column is mounted on the inside of the fixed cylinder. A right opening and closing plate is welded to the outer end face, and a left opening and closing plate is installed at the bottom end of the feed hopper at a symmetrical position with the right opening and closing plate. The height of the limestone powder at the top of the conveyor belt will be detected by the flow radar. When the limestone size is too large, The amount of powder produced after crushing will increase, then control the retraction of the second hydraulic push rod and the first hydraulic push rod to reduce the number of falling limestone blocks. When the same batch of stones is smaller, control the right opening and closing plate and The left opening and closing plate opens at a larger angle, thereby increasing the flow of stones to control the crusher to always work at a balanced load, ensuring stable manufacturing efficiency of limestone products, so that production capacity can be reasonably controlled in advance, and economic benefits can be achieved maximize.

Description

An efficient crushing system for limestone

Technical field

The present invention relates to the technical field of limestone crushing, specifically an efficient crushing system for limestone.

Background technique

The limestone crushing system mainly consists of limestone unloading warehouse, plate feeder, crusher, conveyor line, spray dust suppression and other major equipment. By transporting the raw limestone to the unloading mechanism, and then transporting it to the crusher through the conveyor belt, the large amount of limestone is crushed. The main task of the entire limestone crushing system is to crush blocks of raw limestone to facilitate subsequent processing into other limestone products;

However, the existing limestone crushing system lacks a unified flow control system, which results in irregular amounts of raw limestone being added to the crusher. This results in the crusher sometimes running at high power and sometimes running empty, which greatly reduces the cost. In order to avoid the above technical problems, it is necessary to provide an efficient crushing system for limestone to overcome the defects in the prior art.

Contents of the invention

The present invention provides an efficient crushing system for limestone, which can effectively solve the problem that the existing limestone crushing system proposed in the above-mentioned background technology lacks a unified flow control system, resulting in an irregular amount of raw limestone being added to the crusher. , which will lead to the problem that sometimes the crusher runs at high power, and sometimes it runs empty, which greatly reduces the limestone crushing efficiency.

In order to achieve the above object, the present invention provides the following technical solution: an efficient crushing system for limestone, including a base, and a flow control assembly is installed on the top of the base;

The flow control assembly includes a feed hopper, a fixed cylinder, a rotating column, a right opening and closing plate, a left opening and closing plate, a fixed seat, a rotating seat, a first hydraulic push rod, a connecting seat, a first partition, a second partition, an inlet Material chamber, second hydraulic push rod, installation chamber, installation plate, surveillance camera, plate chain machine, crusher, flow radar and conveyor belt;

A feed hopper is installed at the top of the base, and a fixed cylinder is installed at the bottom of the feed hopper. A rotating column is installed on the inside of the fixed cylinder, and a right opening and closing plate is welded to the outer end of the rotating column. A left opening and closing plate is installed at the bottom end of the feed hopper at a position symmetrical to the right opening and closing plate. A fixed seat is installed on the inner side of the feed hopper. A rotating base is installed on the inner side of the fixed base. The rotating base is installed on the inner side of the rotating base. A first hydraulic push rod is installed, and a connecting seat is installed on the top of the right opening and closing plate;

A first partition is installed on the inner side of the feed hopper, and a second partition is installed on the inner side of the feed hopper at a position symmetrical to the first partition, and a formation is formed between the first partition and the second partition. There is a feeding chamber, and a second hydraulic push rod is installed on the inside of the feeding hopper at a position symmetrical to the first hydraulic push rod. An installation cavity is formed between the first partition and the feeding hopper. A mounting plate is installed on the top of the bucket, and a surveillance camera is installed on the bottom of the mounting plate. A plate chain machine is provided at the bottom of the feed hopper, and a crusher is provided on one side of the plate chain machine. The crusher A flow radar is provided on one side of the crusher, and a conveyor belt is provided on the bottom of the crusher.

Preferably, the telescopic end of the first hydraulic push rod is rotatably connected to a connecting seat. There are two connecting seats, and the two connecting seats are symmetrically installed on the top of the right opening and closing plate.

Preferably, a movable hole is provided on the inner side of the fixed cylinder at a position corresponding to the rotating column, and the rotating column is rotatably connected to the fixed cylinder through the movable hole.

Preferably, there are two installation cavities, the two installation cavities are symmetrically formed at the inner position of the feed hopper, and the two first hydraulic push rods are installed at the inner position of the installation cavity.

Preferably, there are two fixed seats, and the two fixed seats are symmetrically installed on the inner wall of the feed hopper. The input ends of the monitoring camera, plate chain machine, crusher, flow radar and conveyor belt are all connected to the external controller. The output terminal is electrically connected.

Preferably, a dust suppression component is installed on the top of the feed hopper;

The first nozzle trough plate includes a dust suppression nozzle, a second nozzle trough plate, a water inlet pipe, a positioning plate, a booster pump, a limit plate, a dust suppression glass, an injection pipe, a diverter pipe, an injection hole, a recovery trough plate, a waste sinks and waste pipes;

A first nozzle trough plate is installed on the top of the feed hopper, a dust suppression nozzle is installed on one end face of the first nozzle trough plate, and a dust suppression nozzle is installed on the top of the feed hopper at a symmetrical position with the first nozzle trough plate. The second nozzle trough plate has a water inlet pipe connected to the water inlet end of the first nozzle trough plate, a positioning plate is installed on one end of the feed hopper, and a booster pump is installed on the top of the positioning plate. A limit plate is installed on one end of the installation plate. A dust suppression glass is installed on the bottom end of the limit plate. A spray pipe is installed on one end of the dust suppression glass. The water inlet end of the spray pipe is connected to a shunt. pipe, a spray hole is provided on the outside of the spray pipe, a recovery tank plate is installed on the other end surface of the dust suppression glass, and a waste water tank is provided on one end surface of the recycling tank plate at a position corresponding to the dust suppression glass. The water outlet end of the recovery tank plate is connected to a wastewater pipe.

Preferably, there are several dust suppression nozzles, and the plurality of dust suppression nozzles are equidistantly installed on one end surface of the first nozzle slot plate, and the water inlet end of the water inlet pipe is connected to the water outlet end of the booster pump.

Preferably, there are several injection holes, and the plurality of injection holes are equidistantly located at the corresponding position between one end face of the injection pipe and the dust suppression glass, and the water inlet end of the booster pump is connected to an external water source. The input end of the booster pump is electrically connected to the output end of the external controller.

Compared with the existing technology, the beneficial effects of the present invention are: the structure of the present invention is scientific and reasonable, and it is safe and convenient to use:

1. A flow control component is provided. The height of the limestone powder at the top of the conveyor belt is detected through the flow radar. When the size of the limestone is too large, the amount of powder produced after crushing will increase, and the second hydraulic push rod and the third hydraulic push rod are controlled. A hydraulic push rod retracts to reduce the number of falling limestone blocks. When the stones in the same batch are smaller, the right and left opening and closing plates are controlled to open at a larger angle, thereby increasing the flow of stones to control crushing. The machine always works at a balanced load, and ensures continuous crushing of limestone powder, ensuring stable manufacturing efficiency of limestone products, so that production capacity can be reasonably controlled in advance, and economic benefits can be maximized.

2. A dust suppression component is installed to suppress the dust raised by the limestone through fine water mist. At this time, the fine water mist will evaporate quickly during the landing process, thereby achieving the purpose of dust suppression and preventing dust from being evaporated. Harmful to the health of the operator, the water inside the shunt pipe will enter the inside of the spray pipe. At this time, the mixed liquid will be sprayed through the spray hole to the surface of the dust suppression glass, and then the mixed liquid will slowly wash away the dust on the surface of the dust suppression glass. To the waste water tank, it enters the inside of the recovery tank plate, and then is discharged to the external waste water system through the waste water pipe.

Description of drawings

The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

In the attached picture:

Figure 1 is a schematic structural diagram of the present invention;

Figure 2 is a schematic structural diagram of the flow control assembly of the present invention;

Figure 3 is a schematic diagram of the installation structure of the second partition of the present invention;

Figure 4 is a schematic diagram of the installation structure of the installation plate of the present invention;

Figure 5 is a schematic diagram of the installation structure of the pulverizer of the present invention;

Figure 6 is a schematic structural diagram of the dust suppression assembly of the present invention;

Figure 7 is a schematic diagram of the installation structure of the wastewater pipe of the present invention;

Numbers in the figure: 1. Base;

2. Flow control component; 201. Feed hopper; 202. Fixed cylinder; 203. Rotating column; 204. Right opening and closing plate; 205. Left opening and closing plate; 206. Fixed seat; 207. Rotating seat; 208. First hydraulic pusher Rod; 209, connecting seat; 210, first partition; 211, second partition; 212, feed chamber; 213, second hydraulic push rod; 214, installation chamber; 215, installation plate; 216, surveillance camera; 217. Plate chain machine; 218. Crusher; 219. Flow radar; 220. Conveyor belt;

3. Dust suppression component; 301. First nozzle trough plate; 302. Dust suppression nozzle; 303. Second nozzle trough plate; 304. Water inlet pipe; 305. Positioning plate; 306. Booster pump; 307. Limit plate; 308. Dust suppression glass; 309. Injection pipe; 310. Diverter pipe; 311. Injection hole; 312. Recovery tank plate; 313. Waste water tank; 314. Waste water pipe.

Detailed ways

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

Embodiment: As shown in Figures 1-7, the present invention provides a technical solution, an efficient crushing system for limestone, including a base 1, with a flow control assembly 2 installed on the top of the base 1;

The flow control assembly 2 includes a feed hopper 201, a fixed cylinder 202, a rotating column 203, a right opening and closing plate 204, a left opening and closing plate 205, a fixed seat 206, a rotating seat 207, a first hydraulic push rod 208, a connecting seat 209, and a first partition. Plate 210, second partition 211, feed chamber 212, second hydraulic push rod 213, installation chamber 214, installation plate 215, surveillance camera 216, plate chain machine 217, crusher 218, flow radar 219 and conveyor belt 220;

A feed hopper 201 is installed at the top of the base 1, and a fixed cylinder 202 is installed at the bottom of the feed hopper 201. A rotating column 203 is installed on the inside of the fixed cylinder 202, and a rotating column 203 is installed on the inner side of the fixed cylinder 202 at a position corresponding to the rotating column 203. The movable hole, the rotating column 203 is connected to the fixed cylinder 202 through the movable hole, which is conducive to the uniform rotation of the right opening and closing plate 204. The right opening and closing plate 204 is welded to the outer end face of the rotating column 203, and the bottom end of the feed hopper 201 and the right opening and closing plate 204 A left opening and closing plate 205 is installed at a symmetrical position, a fixed base 206 is installed inside the feed hopper 201, a rotating base 207 is installed on the inner side of the fixed base 206, and a first hydraulic push rod 208 is installed on the inner side of the rotating base 207. The right opening A connecting seat 209 is installed on the top of the closing plate 204. The telescopic end of the first hydraulic push rod 208 is rotationally connected to the connecting seat 209. There are two connecting seats 209. The two connecting seats 209 are symmetrically installed on the top of the right opening and closing plate 204 for convenience. Quickly open and close the right opening and closing plate 204 and the left opening and closing plate 205;

A first partition 210 is installed on the inside of the feed hopper 201. A second partition 211 is installed on the inside of the feed hopper 201 at a position symmetrical to the first partition 210. Between the first partition 210 and the second partition 211 A feed cavity 212 is formed, a second hydraulic push rod 213 is installed at a position symmetrical to the first hydraulic push rod 208 on the inside of the feed hopper 201, and an installation cavity 214 is formed between the first partition 210 and the feed hopper 201. There are two installation cavities 214. The two installation cavities 214 are symmetrically formed at the inner position of the feed hopper 201. The two first hydraulic push rods 208 are installed at the inner position of the installation cavity 214 to prevent the limestone from damaging the first hydraulic push rod. A hydraulic push rod 208 and a second hydraulic push rod 213, a mounting plate 215 is installed at the top of the feed hopper 201, a monitoring camera 216 is installed at the bottom of the installation plate 215, and a plate chain machine 217 is installed at the bottom of the feed hopper 201. A crusher 218 is provided on one side of the plate chain machine 217, a flow radar 219 is provided on one side of the crusher 218, a conveyor belt 220 is provided at the bottom of the crusher 218, and two fixed seats 206 are provided, and the two fixed seats 206 are symmetrical Installed on the inner wall of the feed hopper 201, the input ends of the surveillance camera 216, the plate chain machine 217, the crusher 218, the flow radar 219 and the conveyor belt 220 are all electrically connected to the output end of the external controller to facilitate the transportation of limestone.

A dust suppression component 3 is installed on the top of the feed hopper 201;

The first nozzle slot plate 301 includes a dust suppression nozzle 302, a second nozzle slot plate 303, a water inlet pipe 304, a positioning plate 305, a booster pump 306, a limit plate 307, a dust suppression glass 308, an injection pipe 309, a diverter pipe 310, Spray hole 311, recovery tank plate 312, waste water tank 313 and waste water pipe 314;

A first nozzle trough plate 301 is installed on the top of the feed hopper 201. A dust suppression nozzle 302 is installed on one side of the first nozzle trough plate 301. A symmetrical position between the top of the feed hopper 201 and the first nozzle trough plate 301 is installed. In the second nozzle trough plate 303, the water inlet end of the first nozzle trough plate 301 is connected with a water inlet pipe 304. There are several dust suppression nozzles 302, and several dust suppression nozzles 302 are installed at equal intervals on one side of the first nozzle trough plate 301. On the side end face, the inlet end of the water inlet pipe 304 is connected to the outlet end of the booster pump 306, which is helpful to prevent dust splashing. A positioning plate 305 is installed on one end face of the feed hopper 201, and a booster pump is installed on the top of the positioning plate 305. Pump 306, a limit plate 307 is installed on one end of the installation plate 215, a dust suppression glass 308 is installed on the bottom of the limit plate 307, a spray pipe 309 is installed on one end of the dust suppression glass 308, and the water inlet of the spray pipe 309 A shunt pipe 310 is connected to the end of the injection pipe 309. There are injection holes 311 on the outside of the injection pipe 309. There are several injection holes 311. Several injection holes 311 are equidistantly opened at the corresponding positions of one end surface of the injection pipe 309 and the dust suppression glass 308. At , the water inlet end of the booster pump 306 is connected to the external water source, and the input end of the booster pump 306 is electrically connected to the output end of the external controller, which is conducive to more clear observation of the limestone accumulation situation, and the dust suppression glass 308 A recovery chute plate 312 is installed on the other end face of the recovery chute plate 312. A waste water tank 313 is provided on one end face of the recovery chute plate 312 at a position corresponding to the dust suppression glass 308. A waste water pipe 314 is connected to the outlet end of the recovery chute plate 312.

The working principle and usage process of the present invention: First, the operator controls the first hydraulic push rod 208 and the second hydraulic push rod 213 to expand and contract outward, thereby controlling the right opening and closing plate 204 and the left opening and closing plate 205 to open outward. At this time, the material is fed The bottom of the bucket 201 will be opened, and then large pieces of limestone will be poured into the inside of the feed hopper 201 through the external transporter. As the right opening and closing plate 204 and the left opening and closing plate 205 open, these limestones will fall to the top of the plate chain machine 217 position, at this time the plate chain machine 217 will transport the limestone plate chain to the top position of the crusher 218, and then the crusher 218 will crush the limestone, and then the crushed limestone will fall to the top position of the conveyor belt 220 is transported to the next process. At this time, the flow radar 219 will detect the height of the limestone powder at the top of the conveyor belt 220. When the powder reaches the predetermined height, it means that the limestone inside the crusher 218 is in a sufficient state. At this time, it is not necessary to It is necessary to adjust the telescopic lengths of the first hydraulic push rod 208 and the second hydraulic push rod 213, and then the external transport vehicle can continue to pour large pieces of limestone into the inside of the feed chamber 212. Then, because the sizes of the limestone are different, when the limestone When the specification is too large, the amount of powder produced after crushing will increase. At this time, the crusher 218 will be fully powered, causing the height of the powder at the top of the conveyor belt 220 to increase. At this time, after the flow radar 219 detects the data, the control The second hydraulic push rod 213 and the first hydraulic push rod 208 retract to reduce the number of falling limestone blocks, thereby preventing the crusher 218 from being damaged due to high-load transportation. After the large rocks are crushed, the flow rate will level off again. At this time, Re-open the angles of the right opening and closing plate 204 and the left opening and closing plate 205. At this time, the flow rate can be increased again. Then when the stones of the same batch are smaller, the right opening and closing plate 204 and the left opening and closing plate 205 are controlled to open to a larger angle. thereby increasing stone flow;

Next, the height of the limestone powder at the top of the conveyor belt 220 is detected by the flow radar 219. When the size of the limestone is too large, the amount of powder produced after crushing will increase, and the second hydraulic push rod 213 and the first hydraulic push rod are controlled. The rod 208 retracts to reduce the number of falling limestone blocks. When the stones of the same batch are smaller, the right opening and closing plate 204 and the left opening and closing plate 205 are controlled to open at a larger angle, thereby increasing the flow of stones to control crushing. Machine 218 always works at a balanced load, and ensures continuous crushing of limestone powder, ensuring stable manufacturing efficiency of limestone products, so that production capacity can be reasonably controlled in advance, and economic benefits can be maximized;

Then, every time the transport truck dumps limestone, a large amount of dust will be generated. At this time, the booster pump 306 is controlled to start, thereby inputting the external water source into the inside of the water inlet pipe 304. At this time, the clean water is input into the first nozzle tank. plate 301 and the inside of the second nozzle slot plate 303, and then the alcohol mixture is sprayed to the inside of the feed chamber 212 through the dust suppression nozzle 302, and the dust raised by the limestone is suppressed through fine water mist. At this time, during suppression The fine water mist will evaporate quickly during the landing process, thereby achieving the purpose of dust suppression and preventing the dust from harming the health of the operator. Then during the dust suppression process, the water inside the shunt pipe 310 will enter the spray pipe 309 Inside, at this time, the mixed liquid will be sprayed to the surface of the dust suppression glass 308 through the injection hole 311, and then the mixed liquid will slowly rush the dust on the surface of the dust suppression glass 308 to the position of the waste water tank 313 and then enter the recovery tank plate 312. inside, and then discharged to the external wastewater system through the wastewater pipe 314.

Finally, it should be noted that the above are only preferred examples of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still Modify the technical solutions described in the foregoing embodiments, or make equivalent replacements for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (8)

1. A high-efficiency crushing system for limestone, comprising a base (1), characterized in that: the top end of the base (1) is provided with a flow control assembly (2);

the flow control assembly (2) comprises a feed hopper (201), a fixed cylinder (202), a rotating column (203), a right opening and closing plate (204), a left opening and closing plate (205), a fixed seat (206), a rotating seat (207), a first hydraulic push rod (208), a connecting seat (209), a first partition plate (210), a second partition plate (211), a feeding cavity (212), a second hydraulic push rod (213), a mounting cavity (214), a mounting plate (215), a monitoring camera (216), a plate link machine (217), a pulverizer (218), a flow radar (219) and a conveying belt (220);

the utility model discloses a novel automatic feeding device for a plastic material, which comprises a base (1), wherein a feeding hopper (201) is arranged at the top end of the base (1), a fixed cylinder (202) is arranged at the bottom end of the feeding hopper (201), a rotating column (203) is arranged at the inner side of the fixed cylinder (202) in a rotating way, a right opening and closing plate (204) is welded on the outer side end face of the rotating column (203), a left opening and closing plate (205) is arranged at the symmetrical position of the bottom end of the feeding hopper (201) and the right opening and closing plate (204), a fixing seat (206) is arranged at the inner side of the feeding hopper (201), a rotating seat (207) is arranged at the inner side of the fixing seat (206) in a rotating way, a first hydraulic push rod (208) is arranged at the inner side of the rotating seat (207), and a connecting seat (209) is arranged at the top end of the right opening and closing plate (204);

first baffle (210) are installed to the inboard of feeder hopper (201), second baffle (211) are installed with first baffle (210) symmetry position department to the inboard of feeder hopper (201), be formed with feed cavity (212) between first baffle (210) and second baffle (211), second hydraulic push rod (213) are installed with first hydraulic push rod (208) symmetry position department to the inboard of feeder hopper (201), be formed with install cavity (214) between first baffle (210) and feeder hopper (201), mounting panel (215) are installed on the top of feeder hopper (201), surveillance camera (216) are installed to the bottom of mounting panel (215), the bottom of feeder hopper (201) is provided with plate chain machine (217), one side of plate chain machine (217) is provided with rubbing crusher (218), one side of rubbing crusher (218) is provided with flow radar (219), the bottom of rubbing crusher (218) is provided with conveyer belt (220).

2. A high efficiency crushing system for limestone as claimed in claim 1, wherein: the telescopic end of the first hydraulic push rod (208) is rotationally connected with the connecting seats (209), the two connecting seats (209) are arranged, and the two connecting seats (209) are symmetrically arranged at the top end of the right opening and closing plate (204).

3. A high efficiency crushing system for limestone as claimed in claim 1, wherein: the inner side of the fixed cylinder (202) is provided with a movable hole at a position corresponding to the rotary column (203), and the rotary column (203) is rotationally connected with the fixed cylinder (202) through the movable hole.

4. A high efficiency crushing system for limestone as claimed in claim 1, wherein: the two mounting cavities (214) are symmetrically formed at the inner side positions of the feeding hopper (201), and the two first hydraulic push rods (208) are mounted at the inner side positions of the mounting cavities (214).

5. A high efficiency crushing system for limestone as claimed in claim 1, wherein: the two fixing seats (206) are arranged, the two fixing seats (206) are symmetrically arranged on the inner wall of the feeding hopper (201), and the input ends of the monitoring camera (216), the plate link chain machine (217), the crusher (218), the flow radar (219) and the conveying belt (220) are electrically connected with the output end of the external controller.

6. A high efficiency crushing system for limestone as claimed in claim 1, wherein: the top end of the feed hopper (201) is provided with a dust suppression component (3);

the first nozzle groove plate (301) comprises a dust suppression nozzle (302), a second nozzle groove plate (303), a water inlet pipe (304), a positioning plate (305), a booster pump (306), a limiting plate (307), dust suppression glass (308), an injection pipe (309), a shunt pipe (310), an injection hole (311), a recovery groove plate (312), a wastewater groove (313) and a wastewater pipe (314);

first shower nozzle frid (301) are installed on the top of feeder hopper (201), dust suppression shower nozzle (302) are installed to one side terminal surface of first shower nozzle frid (301), second shower nozzle frid (303) are installed with first shower nozzle frid (301) symmetry position department in the top of feeder hopper (201), inlet end of first shower nozzle frid (301) is connected with inlet tube (304), locating plate (305) are installed to one side terminal surface of feeder hopper (201), booster pump (306) are installed on the top of locating plate (305), limiting plate (307) are installed to one side terminal surface of mounting panel (215), dust suppression glass (308) are installed to the bottom of limiting plate (307), injection pipe (309) are installed to one side terminal surface of dust suppression glass (308), injection hole (311) are seted up in the outside of injection pipe (309), recovery frid (312) are installed to the opposite side terminal surface of dust suppression glass (308), recovery frid (312) are connected with waste water channel (312) in position (313) are corresponding to one side terminal surface of dust suppression glass (308).

7. A high efficiency crushing system for limestone as claimed in claim 6, wherein: the dust suppression spray heads (302) are provided with a plurality of dust suppression spray heads (302), the dust suppression spray heads (302) are equidistantly arranged on one side end face of the first spray head groove plate (301), and the water inlet end of the water inlet pipe (304) is connected with the water outlet end of the booster pump (306).

8. A high efficiency crushing system for limestone as claimed in claim 6, wherein: the dust suppression device is characterized in that a plurality of injection holes (311) are formed, the injection holes (311) are formed in the corresponding positions of one side end face of the injection pipe (309) and dust suppression glass (308) at equal intervals, the water inlet end of the booster pump (306) is connected with an external water source, and the input end of the booster pump (306) is electrically connected with the output end of an external controller.