Lifting type heating mantle

Abstract

A lifting type heating mantle comprises a heating mantle body, a supporting frame, a lifting mechanism and an electric control cabinet, the heating mantle body is horizontally arranged over a foaming furnace outlet guide roller set in the front-back direction, and the supporting frame is fixedly installed on a rack of the foaming furnace outlet guide roller set and stretches across the upper portion of the heating mantle body. The lifting mechanism is installed on the supporting frame and drives the heating cover body to move up and down, smoke exhaust ducts are arranged on the inner sides of a left side plate and a right side plate of the heating cover body in the front-back direction, smoke exhaust ports are formed in the left front side and the right front side of the heating cover body, and the smoke exhaust port in the left side communicates with the smoke exhaust duct in the left side. The smoke exhaust port on the right side is communicated with the smoke exhaust flue on the right side, the two smoke exhaust ports are connected with a main smoke exhaust pipe of the foaming furnace through hoses, a PLC is arranged in the electric control cabinet, and the PLC is in signal connection with the lifting mechanism. The smoke exhaust device is scientific in design, smoke escape can be avoided, dependence on a power source is reduced, and fire accidents are avoided.

Description

Technical Field

[0001] The utility model relates to the field of PVC calendered artificial leather production, in particular to a lifting type heating cover. Background Art

[0002] In order to meet the needs of customers for PVC calendered artificial leather patterns, after the artificial leather is foamed in the foaming furnace, it is necessary to use a vacuum pattern suction device on the foaming furnace production line to suck the pattern. Before the artificial leather comes out of the foaming furnace to absorb the pattern, a heating cover must be set up to heat the surface layer of the artificial leather (PVC adhesive layer) to melt it before the full pattern can be sucked out. Traditional heating covers have the following disadvantages:

[0003] 1) Artificial leather will produce some oil smoke when heated by the heating tube of the heating hood, and the heating hood covers the artificial leather, so the oil smoke cannot be effectively and timely discharged in an organized manner. Although a smoke collecting hood is installed above the heating hood at the outlet of the foaming furnace, oxygen escape may occur;

[0004] 2) The lifting device of the heating hood is mostly electric. The motor reducer drives the transmission shaft and the sprocket installed on the shaft to rotate, and the lifting chain is hung on the sprocket teeth. The other end of the chain is hinged with the lifting ears welded on the two sides of the heating hood to achieve the rise or fall of the heating hood. There are weak links from the transmission shaft to the lifting ears and lifting chain. Any link disengagement will cause the heating hood to fall accidentally, which is poor in safety. In the event of a power outage, the artificial leather trapped under the heating hood will burn in just 3-5 seconds because the heating hood stores a lot of heat, causing a fire accident.

[0005] 3) Due to the change in the temperature of the artificial leather surface layer, in order to ensure the uniformity of the pattern depth in batches, it is necessary to manually raise or lower the heating cover, or increase or decrease the running speed of the artificial leather.

[0006] In view of the above drawbacks, the utility model provides a lifting type heating cover. Utility Model Content

[0007] The purpose of the utility model is to provide a lifting type heating cover. The utility model is scientifically designed, can avoid smoke escape, reduce dependence on power supply, and avoid fire accidents.

[0008] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0009] The lifting type heating hood comprises a heating hood body, a supporting frame, a lifting mechanism and an electric control cabinet. The heating hood body is horizontally arranged in the front-to-back direction just above the guide roller group at the foaming furnace outlet. The supporting frame is fixedly installed on the frame of the guide roller group at the foaming furnace outlet and spans above the heating hood body. The lifting mechanism is installed on the supporting frame and drives the heating hood body to move up and down. The inner sides of the left and right plates of the heating hood body are respectively provided with exhaust ducts in the front-to-back direction. The left front side and the right front side of the heating hood body are both provided with exhaust ports. The exhaust port on the left is connected to the exhaust duct on the left, and the exhaust port on the right is connected to the exhaust duct on the right. The two exhaust ports are connected to the main exhaust pipe of the foaming furnace through a hose. A PLC controller is arranged in the electric control cabinet, and the PLC controller is connected with the lifting mechanism signal.

[0010] A plurality of heating pipes are installed at intervals between the two smoke exhaust ducts, and a smoke inlet is arranged at the connection between the heating pipe and the smoke exhaust duct.

[0011] The supporting frame includes two left columns and two right columns. The two left columns are fixedly installed at intervals in front and back on the left side of the upper part of the frame of the guide roller group at the foaming furnace outlet and are located on the left side of the heating hood body. The two right columns are fixedly installed at intervals in front and back on the right side of the upper part of the frame of the guide roller group at the foaming furnace outlet and are located on the right side of the heating hood body. The two left columns and the two right columns are arranged in a rectangular array. A crossbeam is fixedly installed between the tops of the two left columns and the two right columns. The crossbeam is a U-shaped channel steel frame. The right sides of the two left columns and the left sides of the two right columns are fixedly installed with linear slide rails along the vertical direction.

[0012] The lifting mechanism includes two worm gear screw lifts, which are symmetrically fixed on the left and right middle parts of the crossbeam, a first ball head nut is threadedly installed on the lower end of the screw of the worm gear screw lift, and a first locking nut is threadedly installed on the screw of the worm gear screw lift, and two sliders spaced front and back are fixedly installed on the left and right sides of the preheating cover, respectively, the two sliders on the left are slidably connected to the two linear slide rails on the left, and the two sliders on the right are slidably connected to the two linear slide rails on the right, respectively, and the left and right middle parts of the preheating cover are fixedly provided with first spherical ears, the lower end ball head of the first ball head nut on the left is coaxially clamped in the first spherical ear on the left, and the lower end ball head of the first ball head nut on the right is coaxially clamped in the first spherical ear on the right, and the PLC controller is respectively connected to the two worm gear screw lift signals.

[0013] The utility model also includes a temperature measuring and controlling component, which includes a temperature controller, which is arranged in an electric control cabinet, and a group of temperature measuring probes are respectively arranged at the front and rear sides of the middle part of the top plate of the heating hood body and at the outlet of the heating hood body, the temperature controller is respectively connected with the signals of the three groups of temperature measuring probes, and the PLC controller is connected with the temperature controller signal.

[0014] Insulation plates are arranged on the left and right sides of the interior of the heating hood body along the front-to-back direction. The insulation plate on the left is fixed to the right side of the left smoke exhaust duct, and the insulation plate on the right is fixed to the left side of the right smoke exhaust duct. The left end of the heating pipe passes through the insulation plate connected to the left smoke exhaust duct and the right side plate on the left, and the right end of the heating pipe passes through the insulation plate on the right and the left side plate of the right smoke exhaust duct. The right side plate of the left smoke exhaust duct and the insulation plate thereon are provided on the upper side of the connection with the heating pipe, and the left side plate of the right smoke exhaust duct and the insulation plate thereon are provided on the upper side of the connection with the heating pipe. The air vents are the smoke inlets.

[0015] The utility model also includes a cold air blowing pipe, which is circumferentially fixed to the left side of the interior of the heating cover body and the right side of the insulation board on the left side, the rear side of the interior of the heating cover body and the right side of the interior of the heating cover body and the left side of the insulation board on the right side. One end of the cold air blowing pipe is blocked, and the other end of the cold air blowing pipe is connected to a compressed air interface. A blowing solenoid valve is arranged at the compressed air interface. A plurality of blowing ports are evenly spaced on the cold air blowing pipe, and a PLC controller is connected to the blowing solenoid valve signal.

[0016] The power of the worm gear screw lift is a hydraulic motor, which is connected to the hydraulic station in the workshop through a hydraulic pipeline. An accumulator is provided on the hydraulic station, and the PLC controller is connected to the hydraulic station signal;

[0017] An upper limit switch is arranged at the upper end of the linear slide rail, and a lower limit switch is arranged at the lower end of the linear slide rail. The PLC controller is respectively connected with the upper limit switch and the lower limit switch signals.

[0018] The utility model has outstanding substantial features and remarkable progress compared with the prior art. Specifically, when the heating hood body of the utility model is in the lower position, it is in the working position. The heating hood body covers the top of the foaming furnace outlet guide roller group and is close to the foaming furnace outlet guide roller group. The slider slides to the lower end of the linear slide rail and contacts the lower limit switch. The over-temperature alarm temperature (the highest artificial leather surface temperature + 5°C) is set by the temperature controller. Each heating tube heats the artificial leather surface layer. Among them, the oil smoke generated by heating enters the two exhaust air ducts through each air vent, and then is discharged to the main exhaust pipe of the foaming furnace through the exhaust air port and the hose to avoid smoke escape. When the temperature detected by the temperature probe exceeds the over-temperature alarm temperature, the temperature controller outputs an over-temperature alarm bell. At the same time, the PLC controller controls the operation of the hydraulic station. The hydraulic station provides hydraulic oil to the hydraulic motor of the worm gear screw lift through the hydraulic pipeline to lift the worm gear screw. When the hydraulic motor of the machine rotates forward, the screw of the worm gear screw lift drives the heating hood body to rise a certain distance through the first ball head nut and the first spherical ear; when the temperature detected by the temperature measuring probe reaches the fire alarm temperature (the highest artificial leather surface temperature + 10℃), the temperature controller outputs the fire alarm bell and the alarm light flashes. At the same time, the PLC controls the hydraulic station and the accumulator to provide hydraulic oil to the hydraulic motor of the worm gear screw lift at the same time. The hydraulic motor of the worm gear screw lift rotates rapidly, and the heating hood body rises rapidly. At the same time, the air blowing solenoid valve is opened, and the compressed air enters the cold air blowing pipe through the compressed air interface, and then the high-temperature gas in the heating hood body is blown away and cooled through each air blowing port to prevent fire. Among them, when the heating hood body rises or falls and hits the corresponding upper limit switch or lower limit switch, the PLC controller controls the hydraulic motor of the worm gear screw lift to stop running to ensure safe operation.

[0019] The lifting mechanism of the utility model adopts the cooperation of a worm gear screw lifter, a first ball head nut and a first spherical lifting ear, which reduces weak links, can effectively prevent the heating cover from accidentally falling, and has high safety. Moreover, the worm gear screw lifter is powered by a hydraulic motor, and the hydraulic station provides hydraulic oil as a power source, which reduces dependence on power supply, ensures that the lifting mechanism can work normally, and avoids the occurrence of fire accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram when the heating cover body of the utility model is in the working position.

[0021] Figure 2 It is a structural schematic diagram when the heating cover body of the utility model is in a non-working position.

[0022] Figure 3 It is a top view of the utility model.

[0023] Figure 4 It is a left view of the heating cover body of the utility model.

[0024] Figure 5 It is a bottom view of the heating cover body of the utility model, which only illustrates one heating tube.

[0025] Figure 6 It is a structural schematic diagram of the connection between the heating pipe and the smoke exhaust duct of the utility model. DETAILED DESCRIPTION

[0026] The embodiments of the present utility model are further described below in conjunction with the accompanying drawings.

[0027] like Figure 1-6 As shown, the lifting type heating hood comprises a heating hood body 4, a supporting frame, a lifting mechanism and an electric control cabinet (not shown in the figure). The heating hood body 4 is horizontally arranged in the front-to-back direction just above the guide roller group 1 at the foaming furnace outlet, the supporting frame is fixedly installed on the frame of the guide roller group 1 at the foaming furnace outlet and spans above the heating hood body 4, the lifting mechanism is installed on the supporting frame and drives the heating hood body 4 to move up and down, the left side plate and the right side plate inner sides of the heating hood body 4 are respectively provided with exhaust air ducts 2 in the front-to-back direction, the left front side and the right front side of the heating hood body 4 are both provided with exhaust air ports 3, the exhaust air port 3 on the left side is connected with the exhaust air duct 2 on the left side, and the exhaust air port 3 on the right side is connected with the exhaust air duct 2 on the right side, the two exhaust air ports 3 are connected with the main exhaust pipe of the foaming furnace (not shown in the figure, it is a conventional device in the field) through a hose, and a PLC controller is arranged in the electric control cabinet, and the PLC controller is connected with the lifting mechanism signal.

[0028] A plurality of heating pipes 7 are installed at intervals between the two smoke exhaust ducts 2 , and a smoke inlet 8 is provided at the connection between the heating pipe 7 and the smoke exhaust duct 2 .

[0029] The supporting frame includes two left columns 9 and two right columns 10. The two left columns 9 are fixedly installed at intervals in front and back on the left side of the upper frame of the guide roller group 1 at the foaming furnace outlet and are located on the left side of the heating hood body 4. The two right columns 10 are fixedly installed at intervals in front and back on the right side of the upper frame of the guide roller group 1 at the foaming furnace outlet and are located on the right side of the heating hood body 4. The two left columns 9 and the two right columns 10 are arranged in a rectangular array. A crossbeam 11 is fixedly installed between the tops of the two left columns 9 and the two right columns 10. The crossbeam 11 is a U-shaped channel steel frame. The right sides of the two left columns 9 and the left sides of the two right columns 10 are both fixedly installed with linear slide rails 12 along the vertical direction.

[0030] The lifting mechanism includes two worm gear screw lifts 13, which are fixedly installed symmetrically on the left and right middle parts of the crossbeam 11. The lower end of the screw of the worm gear screw lift 13 is threadedly installed with a first ball head screw nut 14, and the screw of the worm gear screw lift 13 is threadedly installed with a first lock nut 15 that presses the upper end of the first ball head screw nut 14. The left and right sides of the heating cover body 4 are respectively fixedly installed with two sliders 16 spaced front and back. The two sliders 16 on the left are slidably connected to the left and right sides. The two linear slide rails 12 on the side, the two sliders 16 on the right side are respectively slidably connected to the two linear slide rails 12 on the right side, the left and right middle parts of the heating hood body 4 are fixedly provided with first spherical ears 17, the lower end ball head of the first ball head nut 14 on the left side is coaxially clamped in the first spherical ear 17 on the left side, and the lower end ball head of the first ball head nut 14 on the right side is coaxially clamped in the first spherical ear 17 on the right side, and the PLC controller is respectively connected with the two worm gear screw lifts 13 signals.

[0031] The utility model also includes a temperature measuring and controlling component, which includes a temperature controller, which is arranged in an electric control cabinet. A group of temperature measuring probes 28 are respectively arranged on the front and rear sides of the middle part of the top plate of the heating hood body 4 and at the outlet of the heating hood body 4. The temperature controller is respectively connected to the signals of the three groups of temperature measuring probes 28, and the PLC controller is connected to the temperature controller signal.

[0032] Insulation plates 29 are provided on the left and right sides of the interior of the heating hood body 4 along the front-to-back direction. The insulation plate 29 on the left side of the preheating hood 4 is fixed to the right side of the left smoke exhaust duct 2, and the insulation plate 29 on the right side is fixed to the left side of the right smoke exhaust duct 2. The left end of the heating pipe 7 is connected to the insulation plate 29 on the left side and the right side plate of the left smoke exhaust duct 2, and the right end of the heating pipe 7 is connected to the insulation plate 29 on the right side and the left side plate of the right smoke exhaust duct 2. The right side plate of the left smoke exhaust duct 2 and the insulation plate 29 thereon are provided on the upper side of the connection with the heating pipe 7, and the left side plate of the right smoke exhaust duct 2 and the insulation plate 29 thereon are provided on the upper side of the connection with the heating pipe 7. The ventilation holes are the aforementioned smoke inlet 8.

[0033] The utility model also includes a cold air blowing pipe 30, which is circumferentially fixed to the left side of the interior of the heating cover body 4 and the right side of the insulation board 29 located on the left side, the inner rear side of the heating cover body 4 and the right side of the interior of the heating cover body 4 and the left side of the insulation board 29 located on the right side. One end of the cold air blowing pipe 30 is blocked, and the other end of the cold air blowing pipe 30 is connected to a compressed air interface 31, and a blowing solenoid valve is arranged at the compressed air interface 31. A plurality of blowing ports 32 are arranged at equal intervals on the cold air blowing pipe 30, and a PLC controller is connected to the blowing solenoid valve signal.

[0034] The power of the worm screw lift 13 is a hydraulic motor, which is connected to the hydraulic station of the workshop through a hydraulic pipeline. The hydraulic station is provided with an accumulator, and the PLC controller is connected to the hydraulic station signal;

[0035] An upper limit switch is provided at the upper end of the linear slide rail 12, and a lower limit switch is provided at the lower end of the linear slide rail 12. The PLC controller is connected to the upper limit switch and the lower limit switch signals respectively.

[0036] The electric control cabinet, PLC controller, temperature controller, air blowing solenoid valve, hydraulic station, accumulator, upper limit switch and lower limit switch are not shown in the figure.

[0037] The PLC controller, heating tube 7, temperature controller, worm gear screw lift 13, temperature measuring probe 28, insulation board 29, air blowing solenoid valve, hydraulic motor, hydraulic station, accumulator, upper limit switch and lower limit switch are all conventional devices, and their specific structure and working principle are not described in detail. The control part in the utility model is conventional control technology and does not involve new computer programs.

[0038] When the heating hood body 4 of the utility model is in the lower position, it is in the working position, the heating hood body 4 covers the top of the foaming furnace outlet guide roller group 1 and is close to the foaming furnace outlet guide roller group 1, the slider 16 slides to the lower end of the linear slide rail 12 and contacts the lower limit switch, and the over-temperature alarm temperature (the highest artificial leather surface temperature + 5°C) is set by the temperature controller, and each heating tube 7 heats the artificial leather surface layer, wherein the oil smoke generated by the heating enters the two exhaust air ducts 2 through each air vent, and then is discharged to the main exhaust pipe of the foaming furnace through the exhaust air port 3 and the hose to avoid smoke escape. When the temperature probe 28 detects that the temperature exceeds the over-temperature alarm temperature, the temperature controller outputs an over-temperature alarm bell. At the same time, the PLC controller controls the hydraulic station to work, and the hydraulic station provides hydraulic oil to the hydraulic motor of the worm gear screw lift 13 through the hydraulic pipeline, so that the hydraulic motor of the worm gear screw lift 13 rotates forward, and the worm gear screw lift 13 The lead screw drives the heating hood body 4 to rise a certain distance through the first ball head nut 14 and the first spherical ear 17; when the temperature detected by the temperature measuring probe 28 reaches the fire alarm temperature (the highest artificial leather surface temperature +10°C), the temperature controller outputs the fire alarm bell and the alarm light flashes, and at the same time, the PLC controls the hydraulic station and the accumulator to simultaneously provide hydraulic oil to the hydraulic motor of the worm gear screw lift 13, the hydraulic motor of the worm gear screw lift 13 rotates rapidly, and the heating hood body 4 rises rapidly, and at the same time, the blowing solenoid valve is opened, and the compressed air enters the blowing cold air pipe 30 through the compressed air interface 31, and then the high-temperature gas in the heating hood body 4 is blown away and cooled through each blowing port 32 to prevent fire, wherein, when the heating hood body 4 rises or falls and hits the corresponding upper limit switch or lower limit switch, the PLC controller controls the hydraulic motor of the worm gear screw lift 13 to stop running to ensure safe operation.

[0039] The lifting mechanism of the utility model adopts the cooperation of the worm gear screw lifter 13, the first ball head nut 14 and the first spherical lifting ear 17, which reduces the weak links, can effectively prevent the heating cover from accidentally falling, and has high safety. Moreover, the worm gear screw lifter 13 is powered by a hydraulic motor, and the hydraulic station provides hydraulic oil as a power source, which reduces the dependence on the power supply, ensures that the lifting mechanism can work normally, and avoids the occurrence of fire accidents.

[0040] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. Lifting heating hood, characterized by: It includes a heating hood body, a supporting frame, a lifting mechanism and an electric control cabinet. The heating hood body is horizontally arranged in the front-to-back direction just above the guide roller group at the foaming furnace outlet. The supporting frame is fixedly installed on the frame of the guide roller group at the foaming furnace outlet and spans above the heating hood body. The lifting mechanism is installed on the supporting frame and drives the heating hood body to move up and down. The inner sides of the left and right plates of the heating hood body are respectively provided with exhaust ducts in the front-to-back direction. The left front side and the right front side of the heating hood body are both provided with exhaust ports. The exhaust port on the left is connected with the exhaust duct on the left, and the exhaust port on the right is connected with the exhaust duct on the right. The two exhaust ports are connected with the main exhaust pipe of the foaming furnace through a hose. A PLC controller is arranged in the electric control cabinet, and the PLC controller is connected with the lifting mechanism signal.

2. The lifting heating cover according to claim 1, characterized in that: A plurality of heating pipes are installed at intervals between the two smoke exhaust ducts, and a smoke inlet is arranged at the connection between the heating pipe and the smoke exhaust duct.

3. The lifting heating cover according to claim 2, characterized in that: The supporting frame includes two left columns and two right columns. The two left columns are fixedly installed at intervals in front and back on the left side of the upper part of the frame of the guide roller group at the foaming furnace outlet and are located on the left side of the heating hood body. The two right columns are fixedly installed at intervals in front and back on the right side of the upper part of the frame of the guide roller group at the foaming furnace outlet and are located on the right side of the heating hood body. The two left columns and the two right columns are arranged in a rectangular array. A crossbeam is fixedly installed between the tops of the two left columns and the two right columns. The crossbeam is a U-shaped channel steel frame. The right sides of the two left columns and the left sides of the two right columns are fixedly installed with linear slide rails along the vertical direction.

4. The lifting heating cover according to claim 3, characterized in that: The lifting mechanism includes two worm gear screw lifts, which are symmetrically fixed on the left and right middle parts of the crossbeam, a first ball head nut is threadedly installed on the lower end of the screw of the worm gear screw lift, and a first locking nut is threadedly installed on the screw of the worm gear screw lift, and two sliders spaced front and back are fixedly installed on the left and right sides of the heating hood body, respectively, the two sliders on the left are slidably connected to the two linear slide rails on the left, and the two sliders on the right are slidably connected to the two linear slide rails on the right, respectively, the left and right middle parts of the heating hood body are fixedly provided with first spherical ears, the lower end ball head of the first ball head nut on the left is coaxially clamped in the first spherical ear on the left, and the lower end ball head of the first ball head nut on the right is coaxially clamped in the first spherical ear on the right, and the PLC controller is respectively connected to the two worm gear screw lift signals.

5. The lifting heating cover according to claim 4, characterized in that: It also includes a temperature measuring and controlling component, which includes a temperature controller. The temperature controller is arranged in an electric control cabinet. A group of temperature measuring probes are respectively arranged on the front and rear sides of the middle part of the top plate of the heating hood body and at the outlet of the heating hood body. The temperature controller is respectively connected to the signals of the three groups of temperature measuring probes, and the PLC controller is connected to the temperature controller signal.

6. The lifting heating cover according to claim 2, characterized in that: Insulation plates are arranged on the left and right sides of the interior of the heating hood body along the front-to-back direction. The insulation plate on the left is fixed to the right side of the left smoke exhaust duct, and the insulation plate on the right is fixed to the left side of the right smoke exhaust duct. The left end of the heating pipe is connected to the insulation plate on the left and the right side plate of the left smoke exhaust duct, and the right end of the heating pipe is connected to the insulation plate on the right and the left side plate of the right smoke exhaust duct. The right side plate of the left smoke exhaust duct and the insulation plate thereon are provided on the upper side of the connection with the heating pipe, and the left side plate of the right smoke exhaust duct and the insulation plate thereon are provided on the upper side of the connection with the heating pipe. The air vents are the smoke inlets.

7. The lifting heating cover according to claim 2, characterized in that: It also includes a cold air blowing pipe, which is circumferentially fixed to the left side of the interior of the heating hood body and the right side of the insulation board on the left side, the inner rear side of the heating hood body and the right side of the interior of the heating hood body and the left side of the insulation board on the right side. One end of the cold air blowing pipe is blocked, and the other end of the cold air blowing pipe is connected to a compressed air interface. A blowing solenoid valve is arranged at the compressed air interface. A number of blowing ports are evenly spaced on the cold air blowing pipe, and a PLC controller is connected to the blowing solenoid valve signal.

8. The lifting heating cover according to claim 4, characterized in that: The power of the worm gear screw lift is a hydraulic motor, which is connected to the hydraulic station in the workshop through a hydraulic pipeline. An accumulator is provided on the hydraulic station, and the PLC controller is connected to the hydraulic station signal; An upper limit switch is arranged at the upper end of the linear slide rail, and a lower limit switch is arranged at the lower end of the linear slide rail. The PLC controller is respectively connected with the upper limit switch and the lower limit switch signals.

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