JP4965333B2 - Impact tool - Google Patents

Description

  The present invention relates to a technique for alleviating a reaction force received from a workpiece during a hammer operation in an impact tool that performs a linear hammer operation on a workpiece.

Japanese Laid-Open Patent Publication No. 52-109673 (Patent Document 1) discloses a configuration of an electric hammer provided with a vibration damping device. In this conventional electric hammer, an anti-vibration chamber is formed integrally with the main body housing (and the motor housing) in a region below the main body housing and in front of the motor housing. Accommodates a vibration absorber. And it is comprised so that the vibration of the hammer bit long-axis direction produced in the case of hammer bit drive may be absorbed by the said dynamic vibration absorber.
By the way, the actual hammering operation is performed in a state where the operator applies a pressing force directed forward to the tool body and presses the hammer bit against the workpiece. The tool body is positioned relative to the workpiece at this time by the impact bolt that is moved backward together with the hammer bit pushed into the tool body side (rear) contacting an inelastic body (for example, a cylinder) on the tool body side. Made. When a hammering operation is performed in this positioning state, the hammer bit rebounds with a reaction force received from the workpiece, and the reaction force is transmitted to the tool body. For this reason, in the conventional hammer, a buffer member is interposed between the impact bolt and the non-elastic body on the tool body side, and the reaction force received by the hammer bit by the buffer action of the buffer member is reduced.

However, the conventional electric hammer has a configuration in which vibration is suppressed by a dynamic vibration absorber and reaction force due to rebound of the tool bit is reduced by a buffer member, and a plurality of mechanisms are required for vibration suppression or reduction. There is still room for improvement in this regard.
JP 52-109673 A

  In view of such points, the present invention provides a technique that contributes to rationalization of a mechanism related to vibration suppression of a tool main body generated during hammering work and reduction of a reaction force received from a workpiece after a hammering operation in a hammering tool. Objective.

  In order to achieve the above object, a preferred embodiment of the impact tool according to the present invention includes a tool main body and a positioning elastic body in an impact tool for performing a predetermined hammer operation on a workpiece by an impact operation in a major axis direction of a hammer operating member. And a dynamic vibration absorber. The “predetermined hammering operation” in the present invention is not only a hammering operation in which the hammer operating member performs only a long-axis striking operation, but also a hammer drill that performs a striking operation in the long-axis direction and a rotation operation around the long-axis direction. Work is preferably included. The “hammer actuating member” in the present invention typically corresponds to a tool bit and an impact bolt that transmits a striking force to the tool bit. The dynamic vibration absorber has a weight capable of linear movement in a state where an urging force is applied by an elastic element, and performs vibration damping during hammering work by moving the weight in the long axis direction of the hammer operating member. Prior to the hammering operation, the positioning elastic body contacts the hammer actuating member when the hammer actuating member is pressed against the work piece and pushed into the tool body, thereby positioning the tool body relative to the work piece. In addition, in the positioning state, when the hammer operating member performs a hammering operation on the workpiece, the reaction force due to the rebound from the workpiece acting on the hammer operating member is absorbed. The “positioning elastic body” in the present invention typically corresponds to a spring. The contact between the positioning elastic body and the hammer actuating member is typically performed through an inclusion, but includes a mode in which the positioning elastic body and the hammer operating member are in direct contact.

According to the preferable form of the impact tool of the present invention, the positioning elastic body is constituted by an elastic element as a structural member of the dynamic vibration absorber so that the linear motion of the weight is maintained in the positioning state. It is characterized by the construction . That is, in the present invention, the tool main body is positioned with respect to the workpiece during the hammering operation by the elastic element of the dynamic vibration absorber. Thereby, the dynamic vibration absorber acts as a vibration suppression mechanism that suppresses vibration in the long axis direction of the hammer generated in the tool main body during the hammer operation by the cooperation of the weight and the elastic element, and the elastic element of the dynamic vibration absorber is The hammer operating member is elastically deformed by the reaction force received from the workpiece, thereby absorbing the reaction force and reducing the transmission of the reaction force to the tool body. As described above, according to the present invention, the elastic element of the dynamic vibration absorber is configured to have the functions of positioning the tool body and absorbing the reaction force, thereby reducing the number of parts related to vibration reduction. The structure can be simplified. The elastic element that also serves as the positioning elastic body is usually set so that the operator has a residual pressure that is equal to or greater than the force that presses the hammer operating member against the workpiece.

  According to the further form of the impact tool of this invention, it further has the drive mechanism which drives a hammer action member linearly, and the cylinder which accommodates a drive mechanism. And the weight and elastic element which comprise a dynamic vibration absorber are arrange | positioned circularly outside the cylinder, It is characterized by the above-mentioned. With this arrangement, it is possible to effectively utilize the outer circumferential space of the cylinder, and it is possible to arrange the vibration direction of the weight of the dynamic vibration absorber on the long axis of the hammer actuating member. It can be prevented beforehand.

  According to the further form of the impact tool of this invention, the reaction force which acts on a hammer action member comprises the vibration means which vibrates the said weight actively via the said elastic element, It is characterized by the above-mentioned. The dynamic vibration absorber is originally a mechanism in which a weight is vibrated based on the vibration of the tool body, thereby passively suppressing the vibration of the tool body. In the present invention, the dynamic vibration absorber, which is such a passive vibration damping mechanism, is configured to actively vibrate the weight via the elastic element, so that the vibration damping function of the dynamic vibration absorber can be further enhanced. It becomes. In particular, in the present invention, the reaction force received from the workpiece is used as the weight vibration means, so there is no need to provide an input means for forced vibration, which is effective in reducing power consumption and the structure. Simplification is achieved.

  According to the present invention, in the impact tool, there is provided a technique that contributes to the rationalization of the mechanism related to vibration suppression of the tool body generated during hammering work and reduction of the reaction force received from the workpiece after the impact operation. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. This embodiment will be described using an electric hammer as an example of an impact tool. FIG. 1 is a side sectional view showing the overall configuration of the electric hammer according to the present embodiment, FIG. 2 and FIG. 3 are enlarged sectional views showing main parts of the electric hammer, respectively. FIG. FIG. 3 shows a load state in which the hammer bit is pressed against the workpiece.

  As shown in FIG. 1, the electric hammer 101 according to the present embodiment generally includes a main body 103 that forms an outline of the electric hammer 101, and a tool in the tip region (left side in the drawing) of the main body 103. A hammer bit 119 detachably attached via a holder 137 and a hand grip 109 gripped by an operator connected to the opposite side of the hammer bit 119 of the main body 103 are mainly configured. The main body 103 corresponds to the “tool main body” in the present invention. The hammer bit 119 is held by the tool holder 137 so that the hammer bit 119 can be reciprocated relatively in the major axis direction, and the relative rotation in the circumferential direction is restricted. For convenience of explanation, the hammer bit 119 side is referred to as the front, and the hand grip 109 side is referred to as the rear.

  The main body 103 includes a motor housing 105 that houses the drive motor 111 and a gear housing 107 that houses the motion conversion mechanism 113 and the striking element 115. The rotational output of the drive motor 111 is appropriately converted into a linear motion by the motion conversion mechanism 113 and then transmitted to the striking element 115, and the major axis direction of the hammer bit 119 (the left-right direction in FIG. 1) via the striking element 115. Generates an impact force on. The hand grip 109 is provided with a slide switch 109a that energizes and drives the drive motor 111 when the operator performs a slide operation.

  The motion conversion mechanism 113 includes a drive gear 121 that is rotationally driven in a horizontal plane by the drive motor 111, a crank plate 125 having a driven gear 123 that meshes and engages with the drive gear 121, and a predetermined distance from the rotation center of the crank plate 125. A crank arm 127 having one end connected in an eccentric manner to an eccentric position via an eccentric shaft 126, and a piston 129 as a driver attached to the other end of the crank arm 127 via a connecting shaft 128 It is composed mainly of. The crank plate 125, the crank arm 127, and the piston 129 constitute a crank mechanism.

  As shown in FIGS. 2 and 3, the striking element 115 is disposed on the striker 143 as a striking element slidably disposed on the bore inner wall of the cylinder 141, and slidably disposed on the tool holder 137. An impact bolt 145 serving as an intermediate for transmitting 143 kinetic energy to the hammer bit 119 is mainly used. An air chamber 141 a is formed in the cylinder 141 between the piston 129 and the striker 143. The striker 143 is driven via an air spring of the air chamber 141a of the cylinder 141 accompanying the sliding movement of the piston 129, and collides (hits) an impact bolt 145 as an intermediate element slidably disposed on the tool holder 137. The impact force is transmitted to the hammer bit 119 via the impact bolt 145. The impact bolt 145 and the hammer bit 119 correspond to a “hammer actuating member” in the present invention.

An air chamber 141 a for driving the striker 143 through the action of the air spring is communicated with the outside through an air blow hole 141 b for preventing idling formed in the cylinder 141. In a no-load state in which the hammer bit 119 is not pressed against the workpiece, that is, in a state in which the impact bolt 145 is not pressed in, the striker 143 can be moved to a front position where the vent hole 141b is opened ( (See FIG. 2). On the other hand, in a load state in which the operator applies a forward pressing force to the main body 103 and presses the hammer bit 119 against the workpiece, the striker 143 is pushed by the impact bolt 145 that is moved backward to make the vent hole 141b. It is moved to the rear (closed) rear position (see FIG. 3).
Thus, the vent hole 141b of the air chamber 141a is configured to be opened and closed by the striker 143. When the vent hole 141b is opened, the action of the air spring is invalidated, and when the vent hole 141b is closed. The action of the air spring is effective. In other words, the air hole 141b and the striker 143 constitute an air chamber open type air blow prevention mechanism that prevents the hammer bit 119 from being driven (empty fire) in an unloaded state.

  In addition, the electric hammer 101 according to the present embodiment includes a dynamic vibration absorber 161 for suppressing vibration generated in the main body 103 during the hammering operation. An annular space is formed between the inside of the gear housing 107 that houses the cylinder 141 and the outside of the cylinder 141. The dynamic vibration absorber 161 mainly includes a cylindrical weight 163 disposed in the annular space, and front and rear urging springs 165F and 165R disposed on the front and rear of the weight 163 in the longitudinal direction of the hammer bit. Is done. The biasing springs 165F and 165R correspond to “elastic elements” in the present invention. The front and rear urging springs 165F and 165R impart opposing resilient force to the weight 163 when the weight 163 moves in the longitudinal direction of the hammer bit 119. The portion of the gear housing 107 that accommodates the cylinder 141 is formed by a tubular member (barrel) 108 as a separate member. The tubular member 108 and the gear housing 107 are fixed to each other. In essence, it constitutes one part.

The weight 163 is disposed so that the center thereof coincides with the long axis of the hammer bit 119, and is slidable with the outer peripheral surface thereof in contact with the inner peripheral surface of the gear housing 107. The front and rear urging springs 165F and 165R are respectively constituted by compression coil springs, and are arranged so that their centers coincide with the long axis of the hammer bit 119, as with the weight 163. One end (rear end) of the rear biasing spring 165 </ b> R is in contact with a spring receiving surface 107 a formed on the gear housing 107, and the other end (front end) is in contact with the axial rear end of the weight 163. In addition, one end (rear end) of the front biasing spring 165 </ b> F is in contact with the front end in the axial direction of the weight 163, and the other end (front end) is in contact with the spring receiving member 167.
The spring receiving member 167 is a ring having an overhanging flange portion 167a, and is fitted to the inner peripheral surface of the tubular hole of the tubular member 108 so as to be slidable in the long axis direction of the hammer bit, and the flange portion 167a. The stepped contact surface 108a formed on the tubular member 108 is contacted from the rear and is always held at the contact position.

  The dynamic vibration absorber 161 configured as described above has a damping function against shocking and periodic vibrations generated during hammering (when the hammer bit 119 is driven). In other words, the weight 163 and the urging springs 165F and 165R, which are the vibration damping elements in the dynamic vibration absorber 161, cooperate with the main body 103 of the electric hammer 101 that is the object of vibration damping to perform passive vibration damping. Thereby, the vibration of the electric hammer 101 is effectively suppressed.

  The electric hammer 101 has an impact bolt 145 that is pushed backward together with the hammer bit 119 (piston 129 side) when an operator applies a forward pressing force to the main body 103 to press the hammer bit 119 against the workpiece. The main body 103 is positioned with respect to the workpiece by contacting the main body side member. In the present embodiment, this positioning is performed by the biasing springs 165F and 165R of the dynamic vibration absorber 161 described above via the positioning member 151.

  The positioning member 151 includes a rubber rubber ring 153 formed in a ring shape, a hard front metal washer 155 bonded to the front side in the axial direction of the rubber ring 153, and a rear side in the axial direction of the rubber ring 153. It is a unit part composed of the hard rear metal washer 157, and is fitted into the small diameter portion 145b of the impact bolt 145 in a loose fit. The impact bolt 145 has a stepped portion having a large-diameter portion 145a slidably fitted to the inner peripheral surface of the cylindrical portion of the tool holder 137 and a small-diameter portion 145b formed on the rear side of the large-diameter portion 145a. A tapered portion 145c is formed between the outer peripheral surface of the large diameter portion 145a and the outer peripheral surface of the small diameter portion 145b. And the positioning member 151 is arrange | positioned between the outer peripheral surface of the small diameter part 145b, and the cylindrical inner peripheral surface of the cylindrical member 108. FIG.

  When a load is applied when the hammer bit 119 is pressed against the workpiece by the operator, the taper portion 145c of the impact bolt 145 moved backward together with the hammer bit 119 contacts the positioning member 151 at a predetermined retracted position, and the positioning member 151 is moved. Push backwards. The positioning member 151 pushed backward is brought into contact with the front end surface of the spring receiving member 167. That is, the pressing force of the hammer bit 119 against the workpiece by the operator is received in a resilient manner by the biasing springs 165F and 165R, thereby positioning the main body 103 with respect to the workpiece. Therefore, the urging springs 165F and 165R are set so that the normal worker has a residual pressure that is equal to or greater than the force with which the hammer bit 119 is pressed against the workpiece.

  The positioning member 151 is biased forward by a coil spring 159. As a result, the positioning member 151 moves to a front position where the front end in the axial direction of the front metal washer 155 comes into contact with the rear end portion 137a of the tool holder 137 when the hammer bit 119 is not pressed against the workpiece. And moved and held. Thus, the impact bolt 145 can be placed at a position away from the striker 143 by moving the positioning member 151 to the forward position. As a result, the hammer bit 119 is prevented from being blown by the striker 143 when the piston 129 is driven in a no-load state. The coil spring 159 is arranged outside the cylinder 141 in parallel with the inner diameter side of the urging spring 165F on the front side of the dynamic vibration absorber 161, and a retaining ring whose one end (rear end) in the axial direction is fixed to the cylinder 141. The other end is in contact with the rear end face of the rear metal washer 157 of the positioning member 151.

  Next, the operation of the electric hammer 101 configured as described above will be described. When the drive motor 111 shown in FIG. 1 is energized and driven, the drive gear 121 rotates in a horizontal plane by the rotation output. Then, the crank plate 125 rotates in the horizontal plane via the driven gear 123 engaged with and engaged with the drive gear 121, and thereby the piston 129 slides linearly in the cylinder 141 via the crank arm 127. The At this time, if the hammer bit 119 is in an unloaded state where it is not pressed against the workpiece, the positioning member 151 urged forward by the coil spring 159 is the rear end of the tool holder 137 as shown in FIG. The striker 143 is moved to the front position where the vent hole 141b is opened or is allowed to move. For this reason, when the piston 129 is moved forward, the air in the air chamber 141a is discharged or sucked to the outside through the vent hole 141b, and the action of the compression spring does not occur in the air chamber 141a. In other words, the hammer bit 119 is prevented from being emptied.

  On the other hand, in the load state in which the hammer bit 119 is pressed against the workpiece, as shown in FIG. 3, the striker 143 is pushed backward by the impact bolt 145 pushed backward together with the hammer bit 119, and the ventilation hole 141b. Close. For this reason, the striker 143 linearly moves in the cylinder 141 by the action of the air spring in the sliding movement of the piston 129 and collides with (impacts) the impact bolt 145, thereby reducing its kinetic energy. 119. Thereby, the hammer bit 119 performs a hammering operation in the major axis direction, and performs a hammering operation on the workpiece.

  As described above, the hammering operation is performed in a load state in which the hammer bit 119 is pressed against the workpiece. The hammer bit 119 that is pushed backward by being pressed against the workpiece causes the impact bolt 145 to move backward. The impact bolt 145 that moves backward pushes the positioning member 151 backward. The rear metal washer 157 of the positioning member 151 is brought into contact with the spring receiving member 167 of the dynamic vibration absorber 161. In this manner, the pressing force of the hammer bit 119 against the workpiece by the operator is received in a resilient manner by the biasing springs 165F and 165R of the dynamic vibration absorber 161. As a result, the main body 103 is positioned with respect to the workpiece, and the hammering operation is performed in this state. During the hammering operation, the dynamic vibration absorber 161 performs passive vibration suppression by the weight 163 and the biasing springs 165F and 165R cooperating with the periodic vibration in the long axis direction of the hammer bit generated in the main body 103. Acting as a vibration control mechanism to perform, vibration of the electric hammer 101 can be effectively suppressed.

  In addition, after the hammer bit 119 strikes the workpiece, the hammer bit 119 receives a reaction force from the workpiece and rebounds. The force due to the rebound, that is, the reaction force moves the impact bolt 145, the positioning member 151, and the spring receiving member 167 rearward, and elastically deforms the biasing springs 165F and 165R. That is, the reaction force due to the rebound of the hammer bit 119 is absorbed by the elastic deformation of the urging springs 165F and 165R, and transmission to the main body 103 is reduced. At this time, the rear metal washer 157 of the positioning member 151 opposes the front end surface of the cylinder 141 with a predetermined gap so as to be able to come into contact therewith, thereby defining the maximum retracted position of the positioning member 151. For this reason, the reaction force absorbing action by the urging springs 165F and 165R is performed within the range of the gap.

  As described above, in the present embodiment, the reaction force that the hammer bit 119 receives from the workpiece after the positioning of the main body 103 with respect to the workpiece and the hammer bit 119 is performed prior to the hammering operation. Is absorbed using the urging springs 165F and 165R of the dynamic vibration absorber 161. In other words, the reaction force absorbing spring and the dynamic vibration absorber 161 are used as a common component, which reduces the number of components relating to vibration reduction and simplifies the structure.

  Further, the reaction force caused by the rebound of the hammer bit 119 is input to the weight 163 via the impact bolt 145, the positioning member 151, the spring receiving member 167, and the urging springs 165F and 165R. That is, the reaction force caused by the rebound of the hammer bit 119 acts as a vibration means for positively vibrating (driving) the weight 163 of the dynamic vibration absorber 161. Thereby, the dynamic vibration absorber 161 acts as an active vibration suppression mechanism by forced vibration that actively drives the weight 163, and can more effectively suppress vibration generated in the main body 103 during hammering. For this reason, for example, the amount of vibration input to the dynamic vibration absorber 161 is small, even though the demand for vibration suppression is high, such as when machining is performed while applying a strong pressing force to the main body 103. Even in a work mode in which the dynamic vibration absorber 161 does not operate sufficiently, a sufficient vibration damping function can be ensured.

  In this embodiment, the main body 103 is positioned by the urging springs 165F and 165R. Therefore, it is allowed to move the impact bolt 145 further rearward by bending the biasing springs 165F and 165R by strongly pressing the hammer bit 119 against the workpiece. That is, according to the present invention, when the hammer bit 119 is strongly pressed against the workpiece, the pushing amount of the striker 143 toward the piston 129 can be increased, so that the sucking performance is improved. The suction of the striker 143 is that the piston 129 moves backward to expand the air chamber 141a, thereby cooling the air in the air chamber 141a and reducing the pressure of the air chamber 141a. A phenomenon that moves backwards.

  In the present embodiment, the biasing spring 165F on the front side of the dynamic vibration absorber 161 and the coil spring 159 that biases the positioning member 151 forward are arranged in parallel in the radial direction at the same position on the long axis of the hammer bit 119. It is set as the structure arranged in. Thereby, it is possible to realize a rational arrangement configuration for space saving. In the present embodiment, the rear metal washer 157 of the positioning member 151 is opposed to the front end surface of the cylinder 141 so as to be in contact with the front end surface of the cylinder 141 in a load state where the hammer bit 119 is pressed against the workpiece. The maximum retracted position of the positioning member 151 is defined. Thereby, it is possible to restrict the hammer bit 119 and the impact bolt 145, the striker 143, and the like pushed by the hammer bit 119 from moving backward beyond the maximum retracted position.

  In the present embodiment, the weight 163 and the urging springs 165F and 165R constituting the dynamic vibration absorber 161 are arranged in an annular shape outside the cylinder 141. Thereby, the arrangement which effectively utilizes the outer peripheral space of the cylinder 141 becomes possible. Further, it is possible to arrange the vibration direction of the main body 103 during the hammering operation and the vibration directions of the weight 163 and the biasing springs 165F and 165R on the long axis of the hammer bit 119. It can be prevented that the rotational force in the left and right direction acting around the axis intersecting the long axis direction of the hammer bit) acts.

In the above-described embodiment, the electric hammer 101 is described as an example of the hitting tool. However, the hammer bit 119 is not limited to the electric hammer 101, and the hammer bit 119 performs the hitting operation in the long axis direction and the rotating operation around the long axis. Of course, it can be applied to the hammer drill to be performed.
In the above-described embodiment, the striker 143 controls the opening / closing of the vent hole 141b provided in the cylinder 141 with respect to the blanking prevention mechanism that prevents the hammer bit 119 from being blanked in a no-load state. Although explained, it is not limited to this. For example, an idling prevention mechanism configured to control opening / closing of the vent hole 141b by moving a valve member formed of a slide sleeve slidably disposed outside the cylinder 141 by the positioning member 151 may be used.
In the above-described embodiment, the crank mechanism is used as the motion conversion mechanism 113 that converts the rotation output of the drive motor 111 into a linear motion in order to drive the hammer bit 119 linearly. The conversion mechanism is not limited to the crank mechanism, and for example, a motion conversion mechanism using a swash plate (swash plate) that performs an oscillating motion in the axial direction can be used.

It is a sectional side view showing the whole electric hammer composition concerning an embodiment of the present invention. It is an expanded sectional view showing the principal part of an electric hammer, and shows a no-load state where a hammer bit is not pressed against a work material. It is a plane sectional view showing the principal part of an electric hammer, and shows a load state where a hammer bit was pressed against a work material.

101 Electric hammer (blow tool)
103 Main body (tool body)
105 Motor housing 107 Gear housing 107a Spring receiving surface 108 Cylindrical member 108a Locking surface 109 Hand grip 111 Drive motor 113 Motion conversion mechanism 115 Stroke element 119 Hammer bit 121 Drive gear 123 Driven gear 125 Crank plate 126 Eccentric shaft 127 Crank arm 128 Connecting shaft 129 Piston (Driver)
137 Tool holder 137a Rear end 141 Cylinder 141a Air chamber 141b Vent hole 143 Strike (batter)
145 Impact bolt (meson)
145a Large diameter portion 145b Small diameter portion 145c Tapered portion 151 Positioning member 153 Rubber ring 155 Front metal washer 157 Rear metal washer 158 Retaining ring 159 Coil spring 161 Dynamic vibration absorber 163 Weight 165F, 165R Biasing spring (elastic element, positioning elastic body)
167 Spring receiving member 167a Flange

Claims (3)

A hammering tool that performs a predetermined hammering operation on a workpiece by a hammering operation in the major axis direction of a hammer operating member,
A tool body;
A dynamic vibration absorber having a weight capable of linear motion in a state in which an urging force by an elastic element is applied, and performing vibration suppression during hammering by moving the weight in the longitudinal direction of the hammer operating member;
Prior to the hammering operation, when the hammer actuating member is pressed against the workpiece and pushed into the tool body, the tool body is positioned with respect to the workpiece by contacting the hammer actuating member. In addition, in the positioning state, when the hammer operating member performs a hammer operation on the workpiece, it has a positioning elastic body that absorbs a reaction force due to rebound from the workpiece acting on the hammer operating member,
The positioning elastic body is configured by the elastic element as a constituent member of the dynamic vibration absorber, and is configured to maintain a linear motionable state of the weight in the positioning state. Blow tool. The impact tool according to claim 1,
A drive mechanism for driving the hammer actuating member linearly;
A cylinder that houses the drive mechanism;
The impact tool according to claim 1, wherein the weight and the elastic element constituting the dynamic vibration absorber are arranged in an annular shape outside the cylinder. The impact tool according to claim 1 or 2,
A striking tool characterized in that a reaction force acting on the hammer actuating member constitutes a vibration means for positively vibrating the weight via the elastic element.

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