JP3122872B2 - Insect type actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tapeworm-type actuator which moves relatively to a guide member by one pitch in a stepwise manner, and more particularly, to a position of a work receiver on a jig, and to a work of a work. The present invention relates to an actuator suitable for a positioning drive device when changing according to a model.

[0002]

2. Description of the Related Art Conventionally, as a shading insect type actuator,
According to Japanese Patent Application Laid-Open No. 47-32631, a pair of casings that are extendably connected via a hydraulic jack are slidably engaged with a rod-shaped guide member, and each casing is connected to a guide member. Incorporates a hydraulic brake unit that locks and unlocks the other casing.The brake unit of one casing is locked, the brake unit of the other casing is unlocked, and the other casing is advanced by the hydraulic jack extension operation. And then
The brake unit of the other casing is locked, the brake unit of the other casing is unlocked, and the hydraulic jack contracts to move one casing toward the other casing, and guides the actuator by repeating the above operation. There is known an arrangement in which a step is advanced by one pitch along a member.

[0003]

By the way, in order to improve the responsiveness of the control of the actuator, a valve for controlling the supply and discharge of oil to and from the hydraulic jack and the brake unit is mounted on the casing, and the valve is connected to the hydraulic jack and the brake unit. It is desired to reduce the length of the fluid passage between them as much as possible.

In the above conventional example, a hydraulic jack can be integrated with one casing, and a valve block having a brake unit valve and a hydraulic jack valve incorporated therein is mounted on the one casing.
Fluid pressure can be input to the brake unit and the hydraulic jack via each valve by a common piping member connected to the valve block, but since the other casing moves relative to one casing, a second casing incorporated in the other casing is used. If the valve for the second brake unit is housed in the valve block attached to one casing, the valve block and the second brake unit must be connected via a flexible hose, and the second brake Responsiveness of the control of the unit is deteriorated, and bending and stretching of the flexible hose accompanying the relative movement of the other casing causes fatigue of the hose, resulting in poor durability.

In this case, it is conceivable to attach a valve for the second brake unit to the other casing. However, in this case, a piping member connected to the pressure source is separately provided on one casing side and the other casing side. Must be done, and piping management becomes troublesome.

Further, in the above-mentioned conventional example, since the step is performed at the pitch corresponding to the stroke of the hydraulic jack in any of the reciprocating motions, the step pitch in the forward movement and the step pitch in the backward movement are different. When the actuator is used as a positioning drive device for positioning the work receiver on the jig, the position of the work receiver can be changed only at a pitch that is an integral multiple of the step pitch, thereby impairing the degree of freedom of the position change.

Further, in the above conventional example, since the actuator is constituted by two casings which move relatively,
Only a part of the actuator (one of the two casings) can be used as a fixed part of a driven object such as a work receiver, and the positioning rigidity and accuracy of the driven object are impaired.

When the actuator is prevented from rotating with respect to the guide member, it is necessary to provide a second guide member parallel to the guide member and form an engaging portion for the second guide member in each casing. The actuator is long in the longitudinal direction of the guide member. If an engagement portion for preventing rotation is further provided on the guide member, the size of the actuator increases and the weight increases.

SUMMARY OF THE INVENTION In view of the above, the present invention makes it possible to simplify the handling of piping members by making it possible to step by using a single casing and to provide rigidity for positioning a driven object. , To ensure accuracy, and to make a difference between the step pitch at the time of forward movement and the step pitch at the time of backward movement,
It is another object of the present invention to provide a small and light scaleworm actuator that can be prevented from rotating with respect to the guide member.

[0010]

In order to achieve the above object,
The present invention relates to a scaleworm actuator that moves relative to a guide member, wherein a casing slidably engaged with a pair of guide members arranged in parallel, and a casing positioned on one guide member side in the casing. A pair of stepping units for forward movement and backward movement, which are incorporated in the casing and positioned on the other guide member side in the casing,
The brake unit includes a brake piston, a lock member that locks and unlocks a casing with respect to one guide member in conjunction with the brake piston, and a biasing unit that biases the brake piston in a locking direction of the lock member. And a pressure chamber that presses the brake piston in the unlocking direction of the lock member, wherein each of the stepping units has a forward direction in the forward direction for the forward stepping unit,
The reciprocating direction is the reverse direction, the reciprocating step unit is the reciprocating direction in the forward direction, and the reciprocating direction is the reverse direction. A clamp member interposed between the stepping piston and the receiving member, the clamping member clamping the other guide member when receiving a pressing force in the opposite direction from the stepping piston, and a stepping member. A pressure chamber for pressing the piston in the opposite direction, a fluid pressure input to the pressure chamber of the forward step unit and the pressure chamber of the brake unit during the forward step, and a backward step unit during the backward step And a fluid supply means for inputting fluid pressure to the pressure chamber of the brake unit and the pressure chamber of the brake unit.

The actuator is prevented from rotating by slidably engaging the casing with a pair of parallel guide members. Further, instead of providing the casing with an engagement portion dedicated to preventing rotation, the actuator is engaged with one guide member. Utilizing the engaging portion for the arrangement space of the brake unit and the engaging portion for the other guide member for the arrangement space of the stepping unit,
Since the brake unit and the step unit can be incorporated into the casing with good space efficiency, the actuator can be reduced in size and weight.

Since the lock member is normally pressed and held in the locked state via the brake piston by the urging means of the brake unit, the casing is locked to one guide member, and the driven object mounted on the actuator is It is positioned and held at a predetermined position.

When fluid pressure is input to the pressure chamber of the forward movement stepping unit, the clamp member of the stepping unit is axially compressed between the stepping piston and the receiving member to clamp the guide member, The stepping piston of the stepping unit becomes immovable with respect to the other guide member, and the casing is pressed in the forward direction by the reaction force due to the fluid pressure in the pressure chamber. At this time, the fluid pressure is also input to the pressure chamber of the brake unit. According to this, the lock member is switched to the unlocked state via the brake piston, and the fluid pressure in the pressure chamber of the forward movement step unit is changed by the fluid pressure. The casing moves in the forward direction by the stroke of the stepping piston.

After this step, both the pressure chamber of the brake unit and the pressure chamber of the forward step unit are opened to the atmosphere.
According to this, the locking member of the brake unit is switched to the locked state, the casing is locked at the stepping position, the clamp member of the stepping unit is switched to the unclamped state, and the biasing force of the receiving member causes the clamp member to be moved. Through the casing, the stepping piston is pushed back to the stroke end position in the forward movement direction with respect to the casing, and returns to the original state. By repeating the above operations, the casing moves in the forward movement direction by one pitch with the stroke of the stepping piston of the forward movement step unit.

When the fluid pressure is input to the pressure chamber of the backward moving unit and the pressure chamber of the brake unit, the casing operates in the same manner as described above by the stroke of the moving piston of the backward moving unit. Step backwards. In this way, since the forward movement and the backward movement are performed using different step units, it is possible to make a difference between the step pitch at the time of the forward movement and the step pitch at the time of the backward movement.

Since the casing has a single casing, a valve block incorporating a valve for the brake unit, a valve for the forward moving step unit, and a valve for the backward moving step unit constituting the fluid supply means is provided. Attached to the casing, a fluid pressure can be input to each unit with high responsiveness from a common piping member connected to the valve block via each valve, and the handling of the piping member to the actuator is simplified. Furthermore, since the actuator is constituted by a single casing, the entire actuator can be used for the fixed portion of the driven object, and the rigidity and accuracy of positioning of the driven object are ensured.

When a heavy object is moved by the actuator, it is desirable to provide a pair of brake units in order to secure the lock. In this case, a pair of brake units are arranged such that the locking direction of the lock member of each brake unit is directed outward in the longitudinal direction of the casing, and the two pistons for brake are locked between the brake pistons of both brake units. It is desirable to provide a common urging means for urging in the direction to share parts.

A pair of forward and backward stepping units are arranged such that the forward direction of each stepping unit is directed outward in the longitudinal direction of the casing, and the receiving members of both stepping units are arranged. Is configured to be urged in the forward direction by a common urging means provided between both receiving members, which is advantageous in that the number of parts can be further reduced.

Various types of lock members and clutch members are conceivable, but these may be constituted by disc spring-shaped members whose inner diameters are reduced when receiving a pressing force from a brake piston or a stepping piston. The structure becomes simpler. In addition, if the lock member and the clamp member are provided with a collet chuck that is externally inserted into the guide member, the durability is improved and the restraining force on the guide member can be increased, which is advantageous.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an arrangement of a work receiver on a jig used in an automobile manufacturing line or the like. A work receiver c, which is a driven object, is attached to an actuator A that moves left and right along the axis, and the position of the work receiver c can be changed according to the type of the work.

The actuator A has a casing 1 slidably engaged with a guide member b. A valve block 2 is mounted on the outer surface of the casing 1 and the valve block 2 is connected to the valve block 2 via a piping member 3 connected thereto. Thus, a pressure fluid, for example, compressed air is supplied, and the actuator A is operated by air pressure. Further, in this embodiment, as shown in FIG. 2, a first and second pair of guide members b parallel to each other are provided.
1 and b2, the casing 1 of the actuator A is slidably engaged with the two guide members b1 and b2 to prevent the actuator A from rotating.

A pair of brake units 4 and 4 are installed in the casing 1 on the first guide member b1 side, and one pair for the right and left movements is located on the second guide member b2 side. stepping unit 5 _first pair, 5 ₂ is incorporated.

Each brake unit 4 includes a brake piston 40 and a lock member 41 that locks and unlocks the casing 1 with respect to the first guide member b1 in conjunction with the piston 40. The lock member 41 is shown in FIG.
As shown in the figure, the disc spring-shaped member 100 is formed with a radial slit extending radially from the inner peripheral side to the middle in the radial direction. When a pressing force is applied from the brake piston 40 to the receiving portion 42 side, the disc spring-shaped member 100 is compressed in the axial direction to reduce its inner diameter. The peripheral edge bites into the guide member b1, and the casing 1 is locked to the first guide member b1.

The brake unit 4 further includes an urging means 43 for urging the brake piston 40 in the locking direction of the lock member 41, that is, an urging means 43 for urging the brake piston 40 toward the receiving portion 42, and an unlocking direction of the lock member 41. A pressure chamber 44 for pressing the lock member 41 normally by the urging force of the urging means 43 to maintain the lock member 41 in a locked state. 41 was switched to the unlocked state.

Although the biasing means 43 is constituted by a coil spring, it may be constituted by an air spring or the like. Further, it is also possible to arrange the receiving portion 42 inside the longitudinal direction of the casing 1 with respect to the brake piston 40 and set the locking direction of the lock member 41 inside the longitudinal direction of the casing 1. Then, the receiving portion 42 is disposed outside the casing 1 in the longitudinal direction with respect to the brake piston 40, and the locking direction is set outside the longitudinal direction of the casing 1, so that the brake pistons 40, 40 can be urged in the locking direction by common urging means 43 arranged between them.

[0026] Migidoyo stepping unit 5 ₁ a stepped piston 50, the receiving Me member 51 is biased to the right toward the stepped piston 50, stepped piston 50 and the receiving Me member 51 , A clamp member 52 capable of clamping the second guide member b2 and a pressure chamber 53 for pressing the stepping piston 50 leftward.

The clamp member 52 is formed of a disc spring-like member 100 similar to the lock member 41, and the receiving member 51 has a piston portion 51a formed at the tail end thereof.
Is biased rightward by a biasing means 54 composed of an air spring. When the stepping piston 50 reaches the right stroke end position, the receiving member 5
The rightward movement of the first stopper part 5 provided on the casing 1
Therefore, the clamp member 52 is always kept in the unclamped state without being compressed in the axial direction. On the other hand, when the stepping piston 50 is pressed to the left by the input of air pressure from the air supply / exhaust port 53a to the pressure chamber 53, the disc spring-like member 1 serving as the clamp member 52
00 is compressed in the axial direction between the receiving member 51 and the inner diameter thereof is reduced, and the inner peripheral edge of the member 100 bites the second guide member b2 to be in a clamped state. Leftward movement is prevented, and the casing 1 is pressed rightward by the reaction force of the air pressure in the pressure chamber 53.
Incidentally, the urging means 54 of the receiving member 51 may be constituted by something other than an air spring such as a coil spring.

[0028] Hidaridoyo stepping unit 5 _2, the only structure itself Migidoyo stepping unit 5 ₁ and direction is in the opposite are identical, the same components as Migidoyo stepping unit 5 ₁ The same reference numerals are given and the description is omitted.

[0029] Incidentally, the left and Migidoyo stepping unit 5 _1, may be disposed Hidaridoyo stepping unit 5 ₂ to the right, in the present embodiment, the right and Migidoyo stepping unit 5 _1, moved to the left for walking the advance unit 5 ₂ disposed on the left side, RyoAyumiSusumu unit 5 _1, 5 ₂
Are arranged adjacent to the inside of the casing 1 in the longitudinal direction thereof.
51 can be urged by a common urging means 54 disposed between them.

The valve block 2 attached to the casing 1 has a pressure chamber 4 of a pair of brake units 4 and 4.
A brake valve 20, 20 of a pair of control supply and exhaust to 4, 44, and Migidoyo valve 21 for controlling the supply and exhaust to the pressure chamber 53 of Migidoyo stepping unit 5 _1, Hidaridoyo increment unit 5 and ₂ of the leftward movement of valve 22 which controls the air supply and exhaust to the pressure chamber 53 is provided. These valves 20, 2
Reference numerals 1 and 22 each include an electromagnetic valve, and are controlled by a signal from a controller (not shown). In addition, each valve 20,
The air supply ports 20a, 21a, 22a and the exhaust ports 20b, 21b, 22b of the intake pipes 21 and 22 are silenced with the common pipe member 3 via intake and exhaust manifold passages 23 and 24 in the valve block 2, respectively. Connected to the vessel 25. still,
Even when the valves 20, 21, 22 are individually mounted on the casing 1, the manifold is mounted on the casing 1,
Air can be supplied from the common piping member 3 to each of the valves 20, 21, 22.

Next, the operation of the actuator A will be described. When causing the actuator A is shifted rightward, first pressure chamber 53 of Migidoyo stepping unit 5 ₁ enter the air pressure clamps the second guide member b2 by the clamp member 52 of the walking advance unit 5 ₁ as described above Te, prevents leftward movement of the stepping piston 50 of the walking advance unit 5 _1, then enter the air pressure in the pressure chamber 44, 44 of the two brake units 4,
The lock members 41, 41 of both brake units 4, 4 are switched to the unlocked state. According to this, the casing 1 by the reaction force due to the air pressure in the pressure chamber 53 of Migidoyo stepping unit 5 ₁ is incremented only stroke right of stepping piston 50 as shown in FIG. 4 (a) .

When the casing 1 advances as described above, the pressure chambers 44, 44 of the brake units 4, 4 are opened to the atmosphere, and as shown in FIG.
Switching the fourth locking members 41, 41 in a locked state, then the pressure chamber 53 of Migidoyo stepping unit 5 ₁ is opened to the atmosphere. According to this, the clamp member 52 switches to the unclamped state, and the urging force of the receiving member 51 causes the stepping piston 50 to relatively move with respect to the casing 1 and the second guide member b2 via the clamp member 52. It is pushed back to the right stroke end position and returns to the state shown in FIG.

[0033] Then, the casing 1 by repeating the operation described above is incremented to 1 pitch addressed right in the stroke of the stepping piston 50 of Migidoyo stepping unit 5 _1. If the air supply and exhaust to the pressure chamber 53 of Hidaridoyo stepping unit 5 ₂ instead Migidoyo stepping unit 5 _1, the same effect as the above, stepping piston 50 of the casing 1 is Hidaridoyo incremented unit 5 ₂ Step left by one pitch with the stroke of.

[0034] In the illustrated example, it is set equal to the stroke of KakuAyumiSusumu unit 5 _1, 5 ₂ of stepping piston 50, and put the difference in the stroke, the position of the workpiece receiving c quite You will be able to make changes with great freedom. For example, 5 mm piston stroke of Migidoyo stepping unit 5 _1, by setting the piston stroke of Hidaridoyo stepping unit 5 ₂ to 2 mm, 2 to the left by 1 KaiAyumiSusumu rightward KaiAyumiSusumu By doing so, the work receiver c can be displaced to the right by 1 mm, and the position can be changed at a smaller pitch than the piston stroke.

When the jig is used, a large thrust force may act on the actuator A via the work receiver c. In order to hold the actuator A at a fixed position against this thrust force, the brake unit 4 is required. It is necessary to increase the restraining force. In this case, it is desired to increase the diameter of the guide member b1 to increase the contact length with the lock member 41. On the other hand, the load when the position of the work receiver c is changed is small, and even if the guide member b2 has a small diameter, the stepping reaction force can be sufficiently received by the clamp member 52 that clamps the guide member b2. In the present embodiment, for the first guide member b1 the brake unit 4, since the selectively using the second guide member b2 as increment unit 5 _1, 5 for _2, the second guide member b2 first guide member b1 The actuator A can be made as small as possible. The actuator A
Depending on the usage example, the load may be always small and the load may be large when the position is changed. In this case, the first guide member b1 may be made thinner and the second guide member b2 may be made thicker.

In the above embodiment, the lock member 4
1 and the clamp member 52 are each formed of the disc spring-shaped member 100. However, as in the embodiment shown in FIG.
The lock member 41 and the clamp member 52 may be configured by fitting the collet chuck 101 externally inserted into the first and b2 to the inner periphery of the disc spring-shaped member 100. In the illustrated example, the collet chuck 101 for the clamp member 52 is the receiving member 51.
It is integrated into. When the lock member 41 is provided with the collet chuck 101, the first guide member b
1 can be securely locked regardless of its moving direction,
Only one brake unit 4 may be used.

The lock member 41 and the clamp member 52
Can be constituted by a plurality of segment plates 102 divided in the circumferential direction as shown in FIG. In this case, as shown in FIG.
Is brought into contact with the brake piston 40 and the stepping piston 50 via a retainer ring 103 supporting the outer edge thereof. According to this, when the pressing force from each of the pistons 40 and 50 acts, the segment plate 102 tilts so that the retainer ring 103 receives the reaction force in the radial direction so as to stand up in the radial direction, and the inner edge portion of each of the guides is moved. Members b1, b
Bite into 2. Incidentally, as in the embodiment shown in FIG. 8, the lock member 41 and the clamp member 52 are connected to the segment plate 1.
02 and the collet chuck 101 may be combined.

Further, the lock member 41 and the clamp member 52
Is a ball-type collet chuck 1 as shown in FIG.
04. The chuck 104
Is an outer race 104a having a tapered inner peripheral surface.
And a collet-shaped inner race 104b having a tapered outer peripheral surface, and a ball 104c interposed between the races 104a and 104b.
a, 104b to a pair of end pieces 104d, 1 at both ends.
When the pressing force in the direction indicated by the arrow is applied to the outer race 104a from the brake or stepping piston, the ball 104c is connected.
, The inner race 104b is reduced in diameter, and the guide members b1 and b2 are clamped. 1 in the figure
04e is a ball retainer.

As described above, various types of the lock member 41 and the clamp member 52 are conceivable. However, in order to reduce the number of parts and to reduce the cost, the disc spring-shaped member 100 is required.
It is preferable to use a combination of the disc spring-shaped member 100 and the collet chuck 101 in order to achieve both cost reduction and durability. In the above embodiment, air is used as the working fluid of the actuator A, but liquid such as oil may be used.

[0040]

As is apparent from the above description, the present invention provides a brake unit incorporated in a single casing and a pair of stepping units for forward and backward movement in the forward and backward directions. Since the fluid pressure can be supplied to these units by distributing them from the common piping member on the casing and supplying the fluid pressure, it is possible to simplify the handling of the piping members with respect to the actuator and to reduce the entire actuator. Since it can be used as a fixed part of the driven object, the rigidity and accuracy of positioning of the driven object can be secured, and the step pitch can be differentiated between forward movement and backward movement. The degree of freedom in changing the position of the camera can be increased. Further, a pair of guide members juxtaposed to stop the actuator from rotating can be efficiently used for the brake unit and the stepping unit, and the size and weight of the actuator can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of use of the actuator of the present invention.

FIG. 2 is a cutaway side view of a first embodiment of the actuator of the present invention.

FIG. 3 is a front view of a disc spring-shaped member used as a lock member or a clamp member in the first embodiment.

FIGS. 4A and 4B are diagrams showing the operation of the first embodiment.

FIG. 5 is a cutaway side view of the second embodiment.

FIG. 6 is a cutaway side view of the third embodiment.

FIG. 7 is a front view of a segment plate used as a lock member or a clamp member in the third embodiment.

FIG. 8 is a cutaway side view of the fourth embodiment.

FIG. 9 is a sectional view of a ball type collet chuck used as a lock member or a clamp member.

[Explanation of symbols]

A Actuator b1 First guide member (one guide member) b2 Second guide member (the other guide member) 1 Casing 2 Valve block (fluid supply means) 4 Brake unit 40 Brake piston 41 Lock member 42 Receiving part 43 Urging means 44 pressure chamber 5 _1, 5 ₂ increment unit 50 stepping piston 51 receives Me member 52 clamping member 53 the pressure chamber 54 urging means 100 disc spring-like member 101 collet chuck

──────────────────────────────────────────────────続 き Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI B23Q 5/34 520C B25J 5/02 Z (56) References JP-A-47-32631 (JP, A) JP-A-58-5506 (JP, A) JP-A-62-49005 (JP, A) JP-A-58-38009 (JP, U) JP-A-60-46744 (JP, U) JP-A-63-126316 (JP, U) 1-83904 (JP, U) 1-122504 (JP, U) 2-25703 (JP, U) 60-116433 (JP, U) U.S. Pat. U.S. Pat. No. 3,176,590 (US, A) U.S. Pat. No. 4,646,088 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F15B 15/00-15/28 B23Q 5/34 520 B25J 5/02 F15B 11/12 F15B 11/18

Claims (6)

(57) [Claims] 1. A scaleworm-type actuator which moves relative to a guide member, comprising: a casing slidably engaged with a pair of guide members arranged in parallel; and a casing positioned on one guide member side of the casing. And a pair of forward and backward stepping units incorporated in the casing by being positioned on the other guide member side, wherein the brake unit comprises a brake piston and a brake A lock member that locks and unlocks the casing with respect to one of the guide members in conjunction with the piston, a biasing unit that biases the brake piston in the lock direction of the lock member, and an unlock direction of the brake piston in the lock member A pressure chamber that presses the forward movement direction with respect to the forward movement step unit, and reverses the backward movement direction with respect to the forward movement step unit. Direction, the backward movement unit is a forward direction, and the forward movement direction is a reverse direction, a stepping piston, a receiving member urged in a forward direction toward the stepping piston, A clamp member interposed between the advancing piston and the receiving member, which clamps the other guide member when receiving a pressing force in the opposite direction from the advancing piston; and A pressure chamber for pressing is provided. Fluid pressure is input to the pressure chamber of the forward movement step unit and the pressure chamber of the brake unit during the forward movement, and the pressure chamber and the brake of the backward movement step unit during the backward movement. Fluid supply means for inputting a fluid pressure to a pressure chamber of the unit is provided. 2. A pair of brake units are arranged such that a locking direction of a lock member of each brake unit is directed outward in a longitudinal direction of a casing, and a pair of brake pistons is provided between brake pistons of both brake units. 2. A scaleworm-type actuator according to claim 1, further comprising a common urging means for urging the actuator in the locking direction. 3. A pair of forward and backward stepping units are disposed such that the forward direction of each stepping unit is directed outward in the longitudinal direction of the casing, and the receiving members of both stepping units are provided. 3. The scaleworm-type actuator according to claim 1, wherein the actuator is urged in a forward direction by a common urging means provided between both receiving members. 4. The lock member receives a pressing force in the lock direction from the brake piston, which is interposed between a brake piston and a receiving portion fixed to a casing facing the brake piston in the lock direction. 2. A disk spring-like member having a reduced inner diameter.
4. The scaleworm-type actuator according to claim 1. 5. The disc spring-like member, wherein the clamp member is interposed between a stepping piston and a reaction force receiving member and has an inner diameter reduced by receiving a reverse pressing force from the stepping piston. 5. The method according to claim 1, wherein:
Item 12. The shading insect type actuator according to Item. 6. The lock member and the clamp member,
6. The apparatus according to claim 1, wherein the apparatus includes a collet chuck externally inserted into the guide member.
Item 12. The shading insect type actuator according to Item.