JPH0726042U - Automatic screw rolling machine - Google Patents

Abstract

(57) [Abstract] [Purpose] By feeding the material between the pair of round dies at the time when the phases of the pair of round dies match, and by rolling the screw part on the material without the time lag, The purpose is to eliminate the occurrence of defective products and to facilitate the maintenance management of workers. The automatic screw rolling machine A comprises a pair of circular dies arranged in parallel and rotating in the same direction, and a material insertion mechanism D for feeding a material W between the pair of circular dies. Pushing member 5 for feeding the material W between the pair of round dies at a predetermined timing in synchronization with the round dies.
0, a holding member 60 that operates in conjunction with the reciprocating movement of the material W of the pushing member 50, and the pushing member 5
Reference numeral 0 denotes a stop means for periodically stopping the reciprocating motion of the pushing member 50 in response to the reciprocating motion thereof. That is, a control switch E for outputting a signal is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention is an automatic thread rolling in which a pair of round dies arranged in parallel are rotated in the same direction and the material is forcedly fed between the pair of round dies to form a thread on a desired material. It is about the board.

[0002]

[Prior art]

 Conventionally, there is a differential speed type rolling machine disclosed in Japanese Utility Model Publication No. 3-41874 as the above-mentioned automatic thread rolling machine. This differential speed rolling machine is equipped with a pair of round dies that rotate at different speeds and in the same direction, and a material feeding mechanism that feeds material between the pair of round dies. The material feeding mechanism is an actuator that forcibly feeds material between the pair of round dies in the same plane as the pair of round dies and in a direction orthogonal to the arrangement direction of the pair of round dies. A signal block that makes one rotation in a cycle in which the phases of the screw threads formed on the pair of circular dies match each other in conjunction with the pair of circular dies, and is rotatably provided corresponding to the rotation path of the signal block. It is equipped with a switch for controlling the time of pushing the material, which detects when the phases of the pair of circular dies match each other due to the approach of the signal block and outputs an operation signal to the actuator. By turning and finely adjusting the switch for controlling the timing of pushing the material, the timing to output the operation signal to the actuator is set so that the material can be fed to the timing when the phases of the pair of circular dies match. can do.

[0003]

[Problems to be solved by the device]

 However, in the above-mentioned conventional differential speed rolling machine, when the material pushing time is controlled by the approach of the signal block in which the timing when the phases of the pair of round dies match each other, the timing is linked to the pair of round dies. The switch can output an operation signal to the actuator by detecting the signal block, but this actuator is a cylinder driven by air to keep the manufacturing cost low. Therefore, the feed speed of the actuator may be slightly changed due to the environment such as changes in the outside temperature, humidity and the pressure in the air tank, and if there is some irregularity in the shape and hardness of the material. In the actuator that feeds the material flexibly, there may be a gap between when the phases of the pair of circular dies match and when the material of the actuator is fed. Defective thread was sometimes occur due to this deviation. Therefore, each time the screw is defective, the actuator can feed the material between the pair of round dies when the phases of the pair of round dies match each other. Since it is necessary to rotate the switch to correct the time when the material is pushed in, there is a problem that many screw defects occur unless the worker manages this rolling machine regularly. Further, when the material is supplied to the tip of the actuator, the material is supplied to the material holding arm for positioning which is temporarily provided at the tip of the actuator. The holding arm retracts, and after confirming the retreat with a sensor etc., wait for the time when the phases of the pair of circular dies match and then feed the material between the pair of circular dies. Therefore, there is a problem that it takes a very long time to complete the process of rolling the thread portion on the material.

[0004]

[The purpose of the device]

 The present invention was devised in view of the above-mentioned conventional problems, and when the phases of a pair of circular dies match, the material can be fed between the pair of circular dies, and the timing shifts. With the aim of not providing an automatic thread rolling machine that can roll the threaded part on the material without any need and at the same time, can facilitate the maintenance management of the worker, and can be manufactured at a low price. There is.

[0005]

[Means for solving the problem]

 This invention is an automatic screw rolling machine equipped with a pair of circular dies arranged in parallel and rotating in the same direction, and a material insertion mechanism for feeding a material between the pair of circular dies. The pressing member that feeds the material between the pair of circular dies at a predetermined timing in cooperation with the round die, the gripping member that operates in conjunction with the reciprocating movement of the material of the pushing member, and the pushing member. Equipped with stop means for periodically stopping the reciprocating motion of the pushing member in response to the reciprocating motion, detecting a time when the phases of the pair of circular dies match each other and outputting a control signal to the stop means. It is to be equipped with a control switch that operates.

[0006]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show an automatic thread rolling machine according to one embodiment of the present invention. In this embodiment, a differential speed rolling machine having different rotation speeds of a pair of circular dies is described as an example. Reveal That is, as shown in FIG. 1, the differential speed type rolling machine A in this embodiment mainly comprises a drive section B, a rolling section C and a material inserting mechanism D.

[About Drive Unit] As shown in FIGS. 2 and 4, the drive unit B is a motor mounting bracket on the bottom of the pedestal with the output shaft 11 of the motor 10 with reduction gear facing upward. A motor 10 with a speed reducer is arranged via (not shown), and the respective sprocket wheels 22, 22 mounted in parallel to the respective die shafts 21, 21 (described later). , The output sprocket 23 mounted on the output shaft 11 of the motor 10 with a reducer is provided in the same plane, and the husband's sprockets 22 and 22 and the output sprocket 23 are mounted on the chain 24. By passing it, the output of the motor can be transmitted. Further, a drive spur gear 25 is mounted on the output shaft 11 of the motor 10 with a reduction gear at a position above the output sprocket 23, and a rotary shaft 28 is rotatably provided so as to project to both sides of an upper surface 27 of the gantry. A clutch brake unit 40, which is a stopping means, is attached to the lower end of the 28, and a driven spur gear 26 is attached to the clutch brake unit 40 (stopping means) so as to appropriately mesh with the drive spur gear 25. ing. 4 is a plan view showing the arrangement of the sprockets 22, 22, 23 and the spur gears 25, 26. The idle sprocket 29 located on the right side of the central portion of FIG. This is an idler for adjusting the tension of a chain 24 that spans between the sprockets 22, 22, 23 of the husband and wife mounted on the output shaft 11 of the motor 10 with reduction gear.

[Rolling Section] As shown in FIGS. 1 and 2, the rolling section is provided with lower supporting members 31 and 31, which are arranged to face the upper surface 27 of the pedestal for distinguishing from the driving section B, and the lower supporting members. The side support members 32, 32 projecting upward from both ends of the members 31, 31 and the upper support members 33, 33 facing the lower support members 31, 31 provided on the upper ends of the side support members. And a substantially frame body. The upper slide body 34 and the lower slide body 35 are provided on both ends of each of the die shafts 21 and 21 via the respective bearings, and the upper slide body 34 includes the upper support members 33, 33, The lower slide member 35 is supported by the lower support members 31, 31 slidably in parallel with each other in the longitudinal direction of the respective support members 31, 33. A round die 20 is provided on each of the die shafts 21 and 21 at a substantially intermediate position between the upper support member 33 and the lower support member 31. Further, as shown in FIG. 5, the control switch E for controlling the clutch brake unit 40 (stopping means) is provided on one side of the die shaft 21 (in this example, the rotation speed of the output shaft of the motor with reduction gear). A cam 42 is attached to the upper end of the die shaft (having the same number of revolutions as the above), a cylindrical member 43 is attached to the upper slide body 34 so as to surround the upper end of the die shaft 21, and an operating cover is provided in the opening 43a of the cylindrical member 43. -44 is rotatably closed with respect to the cylindrical member 43, and a limit switch 41 is provided on the operation cover 44 so as to operate in response to the rotation of the cam 42 attached to the upper end of the die shaft 21. It is installed. As described above, the sprockets 22 are attached to the lower ends of the respective die shafts 21 and 21 arranged in such a state. Further, shaft holes 15 are provided at two positions on the pedestal top surface 27 so that each die shaft 21 can slide with a sufficient margin.

[Material Inserting Mechanism] As shown in FIGS. 1, 2 and 3, the material inserting mechanism D is composed of a pushing member 50 and a gripping member 60, and is installed horizontally on the pedestal upper surface 27. Guide bars 52 and 52 are provided on both sides of a base plate 51 via a pushing member 50, and the guiding members 52 and 52 allow the pushing member 50 to be paired in parallel with each other. It is provided so as to slide horizontally from the direction orthogonal to 20. The pushing member 50 is provided with a shaft 53 provided via a bearing and an upper end of a rotatable shaft 28 projecting at both ends of a pedestal upper surface 27 on which the clutch brake unit 40 (stopping means) is mounted. It is linked via a crank mechanism K. At this time, the rotary body 55 of the crank mechanism K is mounted on the rotary shaft 28, and the linear motion body 56 is mounted on the shaft 53 provided on the pushing member 50. Since the output rotary power can be converted into linear power by the crank mechanism K, the pushing member 50 reciprocates in conjunction with the pair of round dies 20, 20 via the output shaft 11 of the motor 10 with a reduction gear. It can be moved. A shaft hole 16 of a shaft 53 which interlocks the pushing member 50 and the crank mechanism K in correspondence with the reciprocating movement of the pushing member 50 is provided in the base plate 51 with a margin. Further, the clutch brake unit 40 (stopping means) can be turned on and off by a signal output from the control switch E, and the pushing member 50 can be activated by the clutch brake unit 40 turning on and off. It can be activated and deactivated.

Next, as shown in FIG. 2, a notch portion 61 is provided on the lower rear side of the grip member 60 provided on the upper portion of the pushing member 50, and a pinion gear 62 is horizontally fixed to the notch portion 61. The shaft 53 is inserted into a bearing provided on the gripping member 60 and the pushing member 50 via the pinion gear 62, and is fixed by a bolt. By rotating the pinion gear 62, the gripping member 60 is centered on the shaft 53. It can be rotated horizontally. Further, as shown in FIG. 3, a rack gear 63 is provided at a rear portion of the pushing member 50 so as to be appropriately meshed with the pinion gear 62 in a predetermined range so as to be driven. 50 is provided with a convex spring fixing member 65, and a spring 64 is stretched on the spring fixing member 65 so as to abut the front surface of the rack gear 63a. Further, a long bolt 67 horizontally provided on the rear side of the rack gear 63 by a bracket 66 presses the rack gear rear surface 63b as the pushing member 50 moves back and forth (backward), so that the rack gear 63 can be driven forward. In other words, the gripping member 60 rotates in conjunction with the reciprocating movement of the pushing member 50 by the rack bolt 63 pressing the long bolt 67 to rotate the pinion gear 62, so that the gripping member 60 rotates in a predetermined direction (direction of arrow 1). You can do it. When the rack gear 63 is separated from the long bolt 67 as the pushing member 50 reciprocates (forwards), the spring 64 is stretched between the spring fixing member 65 and the rack gear 63. It is possible to urge the gripping member 60 in a direction orthogonal to the pair of circular dies 20, 20 arranged in parallel by being driven backward.

The gripping member 60 will be described in more detail. As shown in FIG. 2, an arm 70 slides on the gripping member 60 about a mounting shaft (not shown) of the arm 70. The upper grip 71 is attached to the front lower part of the arm 70, and the lower grip 72 is attached to the front part of the grip member 60 so that the centers of the respective grips 71, 72 coincide with each other. Further, the rod of the cylinder 73, which is rotatably provided in the axial direction of each of the grippers 71 and 72 and is attached to the rear of the upper part of the grip member 60, is attached to the rear portion of the arm 70 to operate the cylinder 73. Thus, the front of the arm 70 can slide vertically with the mounting shaft (not shown) of the arm 70 as the center, so that the material W can be grasped and released. The material W gripped by the upper grip body 71 and the lower grip body 72 is fed between the pair of round dies 20, 20 by the pushing member 50 in the gripped state, so that the round dies 20, 20 are rotated. Accordingly, the material W can be rotated together with the grippers 71, 72. Further, the feeding rule 75 provided at the lower rear part of the material W holds the material W so as not to escape backward when the material W is fed between the pair of dies 20, 20.

Next, the operation of rolling the thread portion on the material W using the above-described differential speed rolling machine A will be described in sequence. First, as shown in FIGS. 2 and 4, the output of the motor 10 with a reduction gear and the sprockets 22 and 22 having different numbers of teeth mounted on the lower ends of the die shafts 21 and 21 of the pair of dies 20 and 20, respectively. An output sprocket 23 mounted on the shaft 11 and a chain 24 are laid so that the output of the motor can be transmitted to the pair of circular dies 20, 20. The idle sprocket 29 tensions the chain 24. The condition can be adjusted. Then, each time the output shaft 11 of the motor with reduction gear 10 makes two revolutions, the sprockets 22, 22, 23 of the sprockets 22, 22, 23 are aligned so that the phases of the screw threads formed on the pair of circular dies 20, 20 match. The number of teeth and the diameter are set.

Next, the material insertion mechanism D is driven from the drive spur gear 25 mounted on the output shaft 11 of the motor 10 with reduction gear that drives the pair of round dies 20, 20 to the driven spur gear 26, and further. The output of the motor is transmitted to the rotary shaft 28 via the clutch brake unit 40 (stopping means) to which the driven spur gear 26 is attached, and the rotary shaft is rotated via the crank mechanism K for converting the rotary power into the linear power. Since the rotational power from 28 can be directly transmitted to the pushing member 50, the pushing member 50 is reciprocated horizontally from the direction directly intersecting between the pair of circular dies 20, 20 arranged in parallel. be able to. At this time, the number of teeth and the diameter of the spur gears 25 and 26 are set so that the driven spur gear 26 makes one revolution every time the output shaft 11 of the motor 10 with a reduction gear makes two revolutions. As described above, since the phases of the pair of circular dies 20 and 20 are set to constantly match once each time the output shaft 11 of the motor with reduction gear 10 makes two revolutions, The pushing member 50 can reciprocate once each time the phases of the circular dies 20 1 and 20 2 match.

Next, the rack gear 63, which is attached to the pushing member 50 in a predetermined range so as to be driven in association with the reciprocating movement of the pushing member 50, and the holding member 60 which is appropriately meshed with the rack gear 63. By the pinion gear 62 fixed to the notch portion 61, the gripping member 60 can be operated in a predetermined direction (directions of arrows 1 and 2) in accordance with the reciprocating movement of the pushing member 50. That is, as shown in FIG. When the pushing member 50 retracts to the rearmost retracted position (the position of arrow 4), the long bolt 67 can press the rack gear 63 in the forward direction, so that the pinion gear 62 rotates and the gripping member 60 moves to the linear feeder. It is possible to operate up to the material supply position W1 provided at the tip of the material supply passage, that is, the track T. Then, the gripping member 60 operates up to the material supply position W1. By confirming this with a sensor (not shown), the cylinder 73 attached to the rear part of the gripping member 60 can be operated, and the upper gripping body 71 and the lower gripping body provided at the tip of the gripping member 60 can be operated. Both ends of the material W can be gripped by 72.

Then, as the pushing member 50 advances from the rearmost retracted position (the position of arrow 4) while the material W is gripped by the gripping member 60, a tension is provided between the spring fixing member 65 and the rack gear 63. Since the rack gear 63 is pressed backward by the spring 64 provided, the grip member 60 can be returned to the material insertion position W2. That is, the gripping member 60 can be biased in a direction orthogonal to the pair of circular dies 20, 20 arranged in parallel. Further, the working distance of the grip member 60 can be adjusted by rotating the long bolt 67 of the positioning stopper in the axial direction thereof.

Next, as shown in FIG. 5, the pair of round dies 20, one side die shaft 21 (in this example, the number of rotations of the output shaft of the motor with a reduction gear is the same as that of the output shaft). ) The control switch E for controlling the clutch brake unit 40 (stopping means) attached to the upper slide body 34 at the upper end is provided with the die shaft 21 on one side (in this example, the output shaft of the motor with a reduction gear). The operating position can be finely adjusted by operating in response to the rotation of the die shaft (having the same rotational speed as the rotational speed) and rotating the operating cover 44. The control switch E outputs a control signal to the clutch brake unit 40 (stop means) via a counter (not shown) having four contact points, and this counter (not shown). ) Are set to operate in the same manner in count 1 and count 2, and count 3 and count 4. That is, the clutch can be turned on in counts 1 and 2, and the clutch can be turned off in counts 3 and 4, and each time the round die 20 to which the control switch E is attached is rotated. A counter (not shown) is set to sequentially repeat the counts 1 to 4. The material inserting mechanism D is set to reciprocate once when the output shaft 11 of the motor with reduction gear 10 rotates twice. While the material inserting mechanism D reciprocates once, a pair of circular dies 20 Since the phases of 20 and 20 are matched once, when the pushing member 50 is at the most retracted position (position of arrow 4), the clutch is changed from the off operation to the on operation, and the pushing member is moved to the most forward position. The operating position of the limit switch 41 is preset by rotating the operation cover 44 of the control switch E so that the respective phases of the pair of circular dies 20, 20 coincide with each other when the position (the position of arrow 3) is reached. Can be stored. That is, when the pushing member 50 is actuated from the most retracted position (position of arrow 4) by the count of 1 of the counter (not shown) and reaches the most advanced position (position of arrow 3), the count becomes 2 and the pair of round dies 20, Each of the 20 phases matches. When the pushing member 50 reaches the final retracted position (position indicated by arrow 4), the count becomes 3, and the clutch is turned off. However, since the pair of circular dies 20, 20 are rotating, the count becomes 4, and the count becomes 1. Then, the clutch is turned on again. The brake is turned on and off in response to the clutch being turned on and off.

Next, the gripping member 60, which operates in conjunction with the reciprocating movement of the pushing member 50, moves the gripping member 60 as the pushing member 50 retracts to the last retracted position (the position of arrow 4). The material can be operated up to the material supply position W1, and as described above, the material W can be gripped by the grippers 71 and 72 at the material supply position W1, and the gripping member can be moved along with the forward movement of the pushing member 50. 60 can be urged to the material insertion position W2. That is, when the pushing member 50 retreats to the last retracted position (the position indicated by arrow 4), the count becomes 3 and the clutch is turned off, and the material W is gripped by the grippers 71 and 72 while the count becomes 1 via count 4. When the count reaches 1, the clutch is turned on so that the pushing member 50 can move forward while holding the material W. Then, the material W can be fed from the direction orthogonal to the pair of round dies 20, 20 arranged in parallel, and when the pushing member 50 reaches the most advanced position (the position of arrow 3), the count becomes 2 and the pair of dies is moved. Since the phases of the circular dies 20 and 20 match each other, the thread portion is rolled on the material W. When the threaded portion is rolled on the material W, the cylinder 73 attached to the rear portion of the grip member 60 is released, and the material W is stored in the storage case N via the shutter S. The above steps can be periodically repeated as long as the motor 10 with a reduction gear is driven. In addition, it is explained that the pressing member 50 is at the most advanced position (position indicated by arrow 3) at the count 2 and the respective phases of the pair of circular dies 20, 20 are matched with each other so that the threaded portion is rolled on the material W. However, the position is set in order to omit the description of the delicate timing of rolling the threaded portion on the material W.

Therefore, if the automatic thread rolling machine A of the present invention is used, the feeding speed of the actuator will be slightly different due to environmental changes such as changes in outside temperature, humidity and pressure in the air tank as in the conventional case. For example, when the screw threads of the pair of circular dies 20 and 20 are aligned with each other, and when the actuator feeds the material W between the pair of circular dies 20 and 20, there is a deviation. Since the material insertion mechanism D is driven in conjunction with the pair of round dies 20, 20, the material feed rate is always constant. The reciprocating cycle of the material insertion mechanism D and the pair of round dies. There is no deviation from the cycle in which the phases of the 20 and 20 threads match. Even if there is some irregularity in the shape or hardness of the material W, the material insertion mechanism D for feeding the material W is motor driven, so that the material W can be reliably fed between the pair of round dies 20, 20. In addition, even if the material W has a different shape, the clutch break unit 40 (stopping means) sends a screw for each material W. It never happens.

Further, since the conventional differential speed rolling machine is manufactured at low cost, the actuator is a cylinder driven by air (the hydraulic cylinder becomes expensive), but this example In the automatic thread rolling machine A, the pair of round dies 20, 20, the pushing member 50 and the gripping member 60 are driven by the same motor 10 with a reduction gear, so that the actuator for driving the husband and husband is reduced. It is possible to manufacture at low cost.

The control switch E for controlling the clutch brake unit 40 (stopping means) is composed of the limit switch 41 and the cam 42, but the invention is not limited to this. The limit switch 41 includes the cam 42 as a block. Can be changed to a proximity switch, and it is possible to detect when the phases of the screw threads of the pair of round dies 20, 20 match. In addition, each time the output shaft 11 of the motor with reduction gear 10 makes two revolutions, the phases of the pair of circular dies are matched once and the material insertion mechanism D makes one reciprocating motion. The number of rotations and the number of reciprocating motions of each husband can be freely set by changing the number of teeth and the diameter of each sprocket 22, 22, 23 and each spur gear 25, 26 without being limited thereto.

Further, in the above embodiment, the automatic screw rolling machine is described as the differential speed type rolling machine A, but the invention is not limited to this, and the pair of round dies 20, 20 have the same rotation speed. It can also be applied to a high-speed rolling machine. For example, the gripping bodies 71 and 72 provided on the gripping member 60 for gripping the material W in the vertical direction can freely rotate according to the rotation of the material W. Therefore, the material W can be forcibly fed between the pair of circular dies 20, 20 rotating at the same speed by the material inserting mechanism D which is interlocked with the motor with reduction gear 10. Since the screw can be forcibly ejected while rolling the material W while being gripped by the gripping bodies 71, 72, it can be applied to a constant speed rolling machine. Further, although the round die 20 is formed with a plurality of threads, the teeth of the sprocket 22 mounted on the die shaft 21 and the output sprocket 23 mounted on the output shaft 11 of the motor 10 with a reduction gear. By setting the number and diameter so that the different screw threads are in phase each time the circular die 20 rotates, the different screw threads are made to match each time the thread is rolled on the material W. , 20 can be evenly worn.

[0022]

[Effect of device]

 The automatic thread rolling machine of the present invention is an automatic thread rolling machine equipped with a pair of circular dies arranged in parallel and rotating in the same direction, and a material insertion mechanism for feeding a material between the pair of circular dies. A pushing member that feeds the material between the pair of round dies at a predetermined timing in cooperation with the pair of round dies; and a gripping member that feeds the material of the pushing member and that operates in conjunction with the reciprocating motion. The pushing member is provided with a stopping means for periodically stopping the reciprocating movement of the pushing member in response to the forward and backward movement of the pushing member, and detects the time when the phases of the pair of round dies match each other to stop the pushing. Since the means is equipped with a control switch for transmitting a control signal, the insertion speed for feeding the material between the pair of round dies does not change due to the environment and is always constant. Mountain's Since there is no deviation between the time when the phases match and the time when the material is fed between the pair of round dies, it is possible to prevent the occurrence of screw failure and facilitate maintenance of the operator. Since the material can be supplied to the gripping member by interlocking with the pushing member, the time for supplying the material can be greatly shortened and the screw rolling can be performed cyclically in synchronization with the rotation of the pair of round dies. By doing so, the number of screws to be manufactured can be greatly increased compared to the conventional rolling machine, and the pushing member and gripping are linked with the motor with reduction gear that drives a pair of round dies. Since the members are driven, the actuator for driving the husband and wife can be reduced and the manufacturing can be performed at low cost, which is a very excellent effect.

[Brief description of drawings]

FIG. 1 is a plan view showing a differential speed rolling machine according to one embodiment of the present invention.

FIG. 2 is a fragmentary sectional view from the left side of FIG.

FIG. 3 is a plan view of a material insertion mechanism.

FIG. 4 is a layout plan view of the inside of a drive unit in the differential speed type rolling machine of FIG. 1;

FIG. 5 is a vertical cross-sectional configuration diagram of a control switch provided on the die shaft on one side.

[Explanation of symbols]

 A Differential speed rolling machine B Drive section C Rolling section D Material insertion mechanism E Control switch K Crank mechanism W Material 20 Round die 40 Clutch brake unit (stopping means)

Claims (1)

[Scope of utility model registration request] 1. An automatic screw rolling machine comprising a pair of round dies arranged in parallel and rotating in the same direction, and a material inserting mechanism for feeding a material between the pair of round dies, wherein A pushing member that feeds the material between the pair of round dies at a predetermined timing in conjunction with the round die,
A gripping member that operates in conjunction with the reciprocating motion of feeding the material of the pressing member, and further, the pressing member includes stop means that periodically stops the reciprocating motion in response to the reciprocating motion of the pressing member, An automatic screw rolling machine comprising a control switch for detecting a time when the phases of the pair of circular dies match each other and outputting a control signal to the stopping means.