JP4197478B2 - Throw arm structure in baseball practice pitcher - Google Patents

Description

  The present invention relates to a pitching arm structure in a so-called arm-type baseball practice pitcher, and more particularly to a structure of a ball receiving portion in the pitching arm that allows a ball to be placed before the pitching.

  Conventionally, there is a pitch arm structure in the baseball practice pitcher shown in Patent Document 1 below. According to this publication, in the throwing machine, a rotating shaft whose axis extends to the left and right is supported by a gantry so as to be rotatable around the axis, and is attached to the rotating shaft and rotates together with the rotating shaft. A pitching arm is provided. The pitching arm protrudes radially outward from the rotation shaft and protrudes outward from the protruding end of the pitching arm main body in the protruding direction of the pitching arm main body. And a ball receiver.

  In a side view when the pitching arm is in a “ball mounting posture” that protrudes substantially horizontally from the rotating shaft toward the rear thereof, the ball receiving portion extends substantially in the radial direction of the rotating shaft, A ball receiving portion main body having a ball receiving groove on its upper surface that makes it possible to place a ball, and an end on the throwing arm main body side of the ball receiving portion main body that protrudes upward from the ball receiving groove. A stopper projection is provided to prevent the ball placed in the groove from rolling more than a predetermined amount on the pitching arm body side.

  The ball receiving portion is fixed to the projecting end portion of the pitching arm main body by a fastener, and the ball against the pitching arm main body is loosened and fastened in the “ball placement posture” of the pitching arm. The elevation angle of the ball receiving groove of the receiving portion can be adjusted. After the pitching arm is set to the “ball placement posture”, when the ball is placed at a high speed toward the front passing above the rotation shaft, the ball placed in the ball receiving groove is changed to the ball receiving groove. After rolling to the protruding end of the ball receiving portion, the ball is thrown forward.

  Then, the ball thrown as described above is directed to the pitched portion which is a desired pitch target area, more specifically, the strike area of the strike practitioner, and by hitting this ball, The batting practice is supposed to be carried out.

  In addition, when throwing with the pitching machine as described above, the direction of the ball toward the lower side of the pitched part is that the ball of the ball receiving part with respect to the pitching arm main body in the “ball placement posture” of the pitching arm. This is achieved by increasing the elevation angle of the receiving groove, while the direction of the ball toward the height of the pitched portion is achieved by decreasing the elevation angle.

JP-A-8-280868

  By the way, as described above, it is determined by adjusting the elevation angle of the ball receiving groove of the ball receiving portion with respect to the throwing arm main body that the pitched ball is directed toward lowering or raising the pitched portion. Since it is not easy to visually determine the magnitude of the elevation angle, it is considered that it is not easy to accurately point the sphere to lower or raise the pitched portion.

  The present invention has been made paying attention to the above situation, and an object of the present invention is to allow a ball to be thrown by a pitching machine to be accurately directed to a desired position of a thrown part. is there.

In the first aspect of the present invention, a rotating shaft 9 having a shaft center 8 extending in the left-right direction is supported on a gantry 7 so as to be rotatable around the shaft center 8, and is attached to the rotating shaft 9 and rotates together with the rotating shaft 9. A pitching arm 10 is provided. The pitching arm 10 protrudes radially outward from the rotary shaft 9, and the pitching arm main body 11 protrudes from the protruding end of the pitching arm main body 11 in the protruding direction. In the side view when the pitching arm 10 is in a “ball mounting posture” that protrudes substantially horizontally from the rotary shaft 9 toward the rear thereof. A receiving portion 13 extends substantially in the radial direction of the rotating shaft 9 and has a ball receiving portion main body 17 having a ball receiving groove 16 on the upper surface thereof, on which the ball 2 can be placed, and the ball receiving portion main body 17 described above. The ball receiver from the end of the throwing arm body 11 side And a stopper projection 18 for preventing the ball 2 placed above the ball receiving groove 16 from rolling more than a predetermined amount toward the pitching arm main body 11 side. After the above-mentioned “ball mounting posture”, when the ball 2 placed on the ball receiving groove 16 is rotated at a high speed through the rotation shaft 9 and forward, the ball receiving groove 16 In the pitching arm structure in the pitching machine for baseball practice that rolls to the protruding end of the ball receiving portion 13 and then throws toward the front,
The ball receiving portion 13 includes position adjusting means 29 that can adjust the placement position of the ball 2 of the ball receiving groove 16 in the throwing arm 10 in the “ball placing posture”. A nut 30 supported by the stopper projection 18; and a bolt 33 screwed onto the female thread 31 of the nut 30 on its shaft center 32. The shaft center 32 extends substantially parallel to the ball receiving groove 16. The bolt 33 can be moved on the shaft center 32 by twisting the bolt 33, and the rolling of the ball 2 placed in the ball receiving groove 16 is blocked by the stopper projection 18 via the bolt 33. It is what I did.

In addition , the ball receiving portion 13 includes a pair of left and right plate materials 21 and 21 that are overlapped with each other, and each part of the plate materials 21 and 21 that constitute the stopper projection 18 is bulged outwardly, respectively. A pair of bead-shaped bulging portions 36 and 36 extending substantially parallel to the ball receiving groove 16 are formed, and a female screw 31 of the nut 30 is formed between the bulging portions 36 and 36 .

According to a second aspect of the present invention, in addition to the first aspect of the invention, the shaft center 32 passes through the vicinity of the center 37 of the sphere 2 placed in the sphere receiving groove 16.

According to a third aspect of the invention, in addition to the first or second aspect of the invention, a plurality of through holes are formed in the ball receiving portion 13.

  In this section, the reference numerals appended to the above terms are not intended to limit the technical scope of the present invention to the contents of the “Examples” section described later.

  The effects of the present invention are as follows.

According to the first aspect of the present invention, a rotating shaft having a shaft center extending in the left-right direction is supported by a gantry so as to be rotatable about the shaft center, and a pitching arm attached to the rotating shaft and rotating together with the rotating shaft is provided. The pitching arm includes a pitching arm main body that protrudes radially outward from the rotation shaft, and a ball receiving portion that protrudes outward from the protruding end of the pitching arm main body in the protruding direction of the pitching arm main body. The ball receiving portion extends in a substantially radial direction of the rotary shaft in a side view when the pitching arm is in a “ball mounting posture” that protrudes substantially horizontally from the rotary shaft toward the rear thereof. A ball receiving portion main body having a ball receiving groove on its upper surface that allows the ball to be placed, and the ball receiving portion main body projecting upward from the end of the throwing arm main body toward the ball receiving groove. The ball placed in the receiving groove is the throwing arm. A stopper projection that prevents rolling more than a predetermined amount on the body side, and when the pitching arm is set to the `` ball mounting posture '', when it is rotated at a high speed toward the front through the rotation shaft, A pitching arm in a pitcher for baseball practice, in which the ball placed in the ball receiving groove rolls the ball receiving groove to the projecting end of the ball receiving portion and then throws forward. In structure
The ball receiving portion includes position adjusting means that can adjust the position of the ball in the ball receiving groove in the throwing arm of the “ball mounting posture”, and the position adjusting means is supported by the stopper protrusion. A nut and a bolt screwed onto the female thread of the nut on its axis, the shaft center extending substantially parallel to the ball receiving groove, and the bolt is rotated on the axis by twisting the bolt. The ball can be moved, and the rolling of the ball placed in the ball receiving groove is blocked by the stopper projection via the bolt.

  For this reason, if the bolt is twisted, the ball rolling prevention position can be adjusted, and the ball mounting position in the ball receiving groove of the ball receiving portion in the throwing arm in the “ball mounting posture” can be adjusted. In addition, by adjusting the mounting position of the ball in the ball receiving groove, the ball to be thrown by the pitcher body of the pitcher can be directed in a desired direction.

  Since the nut and bolt shafts constituting the position adjusting means extend substantially parallel to the ball receiving groove as described above, the ball mounting position in the ball receiving groove is obtained by twisting the bolt. This adjustment can be finely adjusted. Therefore, the “effect” that the ball thrown by the pitcher can be directed to the desired position of the pitched portion with high accuracy is produced.

Further , the ball receiving portion includes a pair of left and right plate members on which the ball receiving portions are overlapped with each other, and each portion of the plate members constituting the stopper protrusion is bulged outwardly to extend substantially parallel to the ball receiving groove. A pair of bead-shaped bulges are formed, and a female screw of the nut is formed between the bulges .

  For this reason, the nut is integrally formed with the stopper protrusion, that is, the “effect” is achieved with a simple configuration.

According to a second aspect of the present invention, the shaft center passes through the vicinity of the center of the sphere placed in the ball receiving groove.

  For this reason, since the joint surface of the outer peripheral surface of the sphere with respect to the sphere-side end surface of the bolt is substantially orthogonal to the axial center of the bolt, the joint surface of the sphere is inclined with respect to the axial center. Thus, the mounting position of the ball in the ball receiving groove can be adjusted more accurately. Therefore, the “effect” is further promoted.

According to a third aspect of the present invention, a plurality of through holes are formed in the ball receiving portion.

  For this reason, the ball receiving portion tends to be heavy due to the provision of the position adjusting means, but by forming the through hole, the weight of the ball receiving portion is reduced, and the position of the ball receiving portion is adjusted. It is suppressed that it becomes heavy by providing. Therefore, when the pitching arm rotates at a high speed, the centrifugal force tends to be applied to the ball receiving portion in proportion to the square of the speed, but an increase in the load is suppressed.

  Moreover, since the weight reduction of the ball receiving portion is not a notch that has been conventionally employed but a through hole, a decrease in strength of the ball receiving portion due to the through hole is suppressed as compared with the notch.

  In the pitching arm structure of the baseball practice pitcher according to the present invention, the present invention is carried out in order to achieve the object of allowing the ball pitched by the pitcher to be accurately directed to the desired position of the pitched portion. The best mode for doing this is as follows.

  That is, a pitching arm is provided which is supported on the gantry so that a rotation shaft whose axis extends to the left and right is rotatable about the axis, and which is attached to the rotation shaft and rotates together with the rotation shaft. The pitching arm includes a pitching arm main body projecting radially outward from the rotating shaft, and a ball receiving portion projecting outward from the projecting end of the pitching arm main body in the projecting direction of the pitching arm main body. I have.

  In a side view when the pitching arm is in a “ball mounting posture” that protrudes substantially horizontally from the rotating shaft toward the rear thereof, the ball receiving portion extends substantially in the radial direction of the rotating shaft, A ball receiving portion main body having a ball receiving groove on its upper surface that makes it possible to place a ball, and an end on the throwing arm main body side of the ball receiving portion main body that protrudes upward from the ball receiving groove. A stopper projection is provided to prevent the ball placed in the groove from rolling more than a predetermined amount on the pitching arm body side.

  After the throwing arm is set to the “ball placement posture”, when the high-speed rotation is performed forward through the rotation shaft, the ball placed in the ball receiving groove becomes the ball receiving groove. After rolling to the protruding end of the ball receiver, the ball is thrown forward.

  The ball receiving portion includes a position adjusting unit that can adjust a mounting position of a ball in a ball receiving groove in the throwing arm in the “ball mounting posture”, and the position adjusting unit is supported by the stopper protrusion. A nut and a bolt that is screwed onto the female thread of the nut on its axis. The shaft center extends substantially parallel to the ball receiving groove, and the bolt can be moved on the shaft center by twisting the bolt. Rolling of the ball placed in the ball receiving groove causes the bolt to move. It is blocked by the stopper projection.

A pair of left and right plate members on which the ball receiving portions are overlapped with each other, and a pair of plate members that form the stopper projections bulge outward toward the outer sides and extend substantially parallel to the ball receiving grooves. A bead-shaped bulge is formed, and a female screw of the nut is formed between the bulges.

  In order to explain the present invention in more detail, an embodiment thereof will be described with reference to the accompanying drawings.

  In FIG. 1-6, reference numeral 1 denotes an arm-type pitcher for baseball practice, and an arrow Fr indicates the front in the pitching direction of the ball 2 by the pitcher 1.

  The pitcher 1 has a pitcher main body 4 that throws the ball 2 toward the pitched part on the ground 3 that is a ground for baseball practice and forward, and the ball 2 by the pitcher main body 4. A large number of balls 2 can be stored for throwing, and a ball supply device (not shown) that supplies the balls 2 to the pitcher main body 4 one by one, and the pitcher main body 4 and the ball supply device are supported. And a carriage 5 that can be moved to an arbitrary position on the ground 3.

  The pitcher main body 4 is attached to the rotating shaft 9, a pedestal 7 supported by the cart 5, a rotating shaft 9 supported on the pedestal 7 so as to be rotatable about a shaft center 8 extending in the left-right direction. A pitching arm 10 that rotates together with the lever rotating shaft 9 is provided. The pitching arm 10 is fastened by a pitching arm body 11 projecting radially outward from the rotating shaft 9 and a projecting end of the pitching arm body 11 by a fastener 12. And a ball receiving portion 13 projecting outward in the projecting direction.

  As shown by a two-dot chain line in FIG. 2 and FIG. 1, in a side view when the pitching arm 10 is set to a “ball mounting posture” that protrudes substantially horizontally from the rotary shaft 9 toward the rear thereof, The ball receiving portion 13 extends in the radial direction of the rotating shaft 9 and has a ball receiving portion main body 17 having a ball receiving groove 16 on the upper surface thereof, on which the ball 2 can be placed, and the ball receiving portion main body 17. The ball 2 protruding from the end on the pitching arm body 11 side to the upper side of the ball receiving groove 16 and placed on the ball receiving groove 16 rolls to the pitching arm body 11 side more than a predetermined amount. And a stopper projection 18 for blocking.

  In the “ball placement posture” of the throwing arm 10, one ball 2 is supplied from the ball supply device to the ball receiving groove 16 of the ball receiving portion 13. In the “ball placement posture”, The ball receiving groove 16 linearly extends rearward and upward, and the elevation angle of the ball receiving groove 16 of the ball receiving portion 13 with respect to the throwing arm body 11 can be adjusted by loosening and fastening the fastener 12. .

  The ball receiving portion 13 includes a pair of left and right sheet metal plates 21, 21 that are overlapped with each other, and both the plate materials 21, 21 are fixed to each other by rivets that are fixing tools 22. The upper edge portions of the plate members 21 and 21 are bent so as to be separated from each other, and the ball receiving groove 16 is formed by the upper edge portions.

  The pitcher body 4 includes a spring 24 that elastically biases the rotating shaft 9 and a direction around the axis 8 together with the throwing arm 10 against the elastic force of the spring 24. And a reduction motor 25 that is driven to rotate toward A. In this case, the position at which the pitching arm 10 has rotated slightly upward from the “ball placement posture” (the chain line in FIG. 2) is the “initial position” of the pitching arm 10, and 180 ° from this “initial position”. The deviated position is the “neutral position” of the pitching arm 10.

  The pitching arm 10 is rotated at high speed from the “initial position” toward the one direction A from above the “initial position” to above the rotating shaft 9 to the “neutral position” by the urging force of the spring 24. The high-speed rotation range of the pitching arm 10 is the pitching range α. Then, due to the high-speed rotation of the pitching arm 10 in this pitch range α, the ball 2 placed in the ball receiving groove 16 of the ball receiving portion 13 receives the ball receiving groove 16 from the ball receiving portion 13. After rolling to the protruding end of the body 17, the ball is thrown forward.

  On the other hand, the pitching arm 10 is driven by the electric motor 25, passes from below the "neutral position" toward the one direction A under the rotating shaft 9, and passes through the "ball placement posture". The rotation range when the pitching arm 10 returns as described above is set as the return range β, and the pitching arm 10 is in the “ball placement posture” as described above. The sphere 2 is supplied from the sphere supply device to the sphere receiving groove 16 of the sphere receiving portion 13 and placed. Thereafter, the above operation is repeated, and the balls 2 are thrown forward one by one.

  In FIGS. 1 and 4-6, the ball receiving portion 13 determines the mounting position of the ball 2 mounted on the ball receiving groove 16 in the pitching arm 10 in the “ball mounting posture”. Position adjusting means 29 that can be adjusted in the longitudinal direction is provided.

  The position adjusting means 29 includes a nut 30 supported by the stopper protrusion 18, a bolt 33 screwed onto the female screw 31 of the nut 30 on its axis 32, and a screw 33 screwed to the bolt 33 to the stopper. A lock nut 34 that can fix the bolt 33 to the protrusion 18 is provided. The shaft center 32 extends substantially parallel to the ball receiving groove 16, and the bolt 33 can be moved back and forth on the shaft center 32 by twisting the bolt 33. Then, rolling of the ball 2 placed in the ball receiving groove 16 is prevented by the stopper projection 18 through the bolt 33.

  A part of each of the plate members 21 and 21 constituting the stopper projection 18 is bulged outward. Both the bulging portions 36 and 36 have a bead shape extending substantially parallel to the ball receiving groove 16, and the nut 30 is integrally formed with the stopper projection 18 by the both bulging portions 36 and 36. It is supported by. Thus, the female screw 31 of the nut 30 is formed between the two plate members 21 and 21 constituting the stopper projection 18. The shaft 32 passes through the vicinity of the center 37 of the sphere 2 on the sphere receiving groove 16. A plurality of through holes 39 are formed in each plate member 21 of the ball receiving portion 13, and each of the through holes 39 is symmetric.

  According to the above configuration, the ball receiving unit 13 includes the position adjusting means 29 that enables the mounting position of the ball 2 of the ball receiving groove 16 in the pitching arm 10 in the “ball mounting posture” to be adjusted. The means 29 includes a nut 30 supported by the stopper protrusion 18 and a bolt 33 screwed onto the female thread 31 of the nut 30 on the shaft center 32, and the shaft center 32 is inserted into the ball receiving groove 16. The bolt 33 extends substantially in parallel, and the bolt 33 can be moved on the shaft center 32 by twisting the bolt 33, and the rolling of the sphere 2 placed in the ball receiving groove 16 can be moved via the bolt 33 to the stopper. The protrusion 18 prevents the protrusion.

  Therefore, if the lock nut 34 is loosened and the bolt 33 is twisted, the rolling prevention position of the ball 2 can be adjusted, and the ball receiving portion 13 of the pitching arm 10 in the “ball mounting posture” can be adjusted. The mounting position of the sphere 2 in the sphere receiving groove 16 can be adjusted.

  Here, as shown by a solid line in FIGS. 1 and 4-6, when the mounting position of the ball 2 in the ball receiving groove 16 is set to the pitching arm main body 11 side, the pitching arm 10 correspondingly throws the pitching range. When the ball 2 is rotated at a high speed by α and the ball 2 rolls in the ball receiving groove 16 and is thrown, the rolling distance becomes longer, so that the ball 2 is directed to a lower pitched portion. . On the other hand, as shown by the alternate long and short dash line in FIG. 6, when the mounting position of the ball 2 in the ball receiving groove 16 is moved away from the pitching arm main body 11 side, the pitching arm 10 is increased in the pitching range α. Accordingly, the rolling distance when the ball 2 rolls in the ball receiving groove 16 and is thrown is shortened. Accordingly, the ball 2 is directed toward raising the pitched portion. That is, by adjusting the mounting position of the ball 2 in the ball receiving groove 16, the ball 2 thrown by the pitcher body 4 of the pitcher 1 can be directed in a desired direction.

  As described above, since the nut 30 and the shaft center 32 of the bolt 33 constituting the position adjusting means 29 extend substantially parallel to the ball receiving groove 16, the ball receiving groove 16 is twisted by the bolt 33. Fine adjustment is possible for the adjustment of the mounting position of the ball 2 on the head. Therefore, the “effect” that the ball 2 to be pitched by the pitcher 1 can be directed to the desired position of the pitched portion with high accuracy accordingly.

  Further, as described above, the ball receiving portion 13 is provided with a pair of left and right plate materials 21 and 21 that are overlapped with each other, and the female screw 31 of the nut 30 is formed between the two plate materials 21 and 21 constituting the stopper protrusion 18. It is.

  For this reason, the nut 30 is integrally formed with the stopper protrusion 18, that is, the “effect” is achieved with a simple configuration.

  In the above case, each part of the plate members 21 and 21 constituting the stopper projection 18 is bulged outwardly to form a bead, and the nut 30 is formed by the bulged portions 36 and 36. The stopper protrusion 18 is integrally formed.

  For this reason, the stopper projection 18 is projected from the ball receiving portion main body 17 and is cantilevered, and it is difficult to ensure rigidity. However, the stopper projection 18 has both the bulging portions 36. , 36 is reinforced by a simple configuration to ensure a predetermined rigidity.

  Further, as described above, the shaft center 32 passes through the vicinity of the center 37 of the sphere 2 placed in the sphere receiving groove 16.

  For this reason, since the joint surface of the outer peripheral surface of the sphere 2 with respect to the end surface of the bolt 33 on the sphere 2 side is substantially orthogonal to the axial center 32 of the bolt 33, the joint surface of the sphere 2 is the axial center 32. As compared with the case where the sphere 2 is inclined, the mounting position of the sphere 2 in the sphere receiving groove 16 can be adjusted with higher accuracy. Therefore, the “effect” is further promoted.

  Further, as described above, a plurality of through holes are formed in the ball receiving portion 13.

  For this reason, the ball receiving portion 13 tends to be heavy due to the provision of the position adjusting means 29. However, the formation of the through hole 39 reduces the weight of the ball receiving portion 13, and the ball receiving portion. 13 is prevented from becoming heavy due to the provision of the position adjusting means 29. Therefore, when the pitching arm 10 rotates at a high speed, the centrifugal force tends to be applied to the ball receiving portion 13 in proportion to the square of the speed, but an increase in the load is suppressed.

  Moreover, since the weight reduction of the ball receiving portion 13 is not the notch that has been conventionally employed but the through hole 39, the strength reduction of the ball receiving portion 13 due to the through hole 39 is suppressed compared to the notch. Is done.

  FIG. 7 shows another embodiment of the ball receiving portion 13. According to this, a separate nut 30 is supported on the stopper projection 18.

It is an enlarged view of the dashed-two dotted line part in FIG. It is a side view of a pitcher. It is a back surface partial view of a throwing machine. It is a top view of what was shown in FIG. FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. 1. FIG. 2 is an explanatory diagram of a partial enlargement operation of FIG. 1. It is a figure which shows the other Example about a ball | bowl receiving part, and is equivalent to a part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thrower 2 Ball 4 Thrower main body 7 Base 8 Axis center 9 Rotating shaft 10 Throwing arm 11 Throwing arm main body 12 Fastener 13 Ball receiving part 16 Ball receiving groove 17 Ball receiving part main body 18 Stopper protrusion 21 Plate material 29 Position adjustment means 30 Nut 31 Female thread 32 Axle 33 Bolt 36 Bump 37 Center 39 Through hole α Throwing range β Return range

Claims (3)

A rotating shaft having a shaft center extending left and right is supported on a gantry so as to be rotatable about the shaft center, and a pitching arm attached to the rotating shaft and rotating together with the rotating shaft is provided. A pitching arm body projecting radially outward from the pitching arm body, and a ball receiving portion projecting outward from the projecting end of the pitching arm body from the projecting end of the pitching arm body. When viewed from the side when the ball is placed in a “ball-mounting posture” that protrudes substantially horizontally from the shaft toward the rear, the ball receiving portion extends substantially in the radial direction of the rotation shaft, and a ball can be loaded. A ball receiving portion main body having a ball receiving groove on the upper surface thereof, and the ball receiving portion main body projecting upward from the end of the throwing arm main body toward the ball receiving groove, and placed in the ball receiving groove. The ball is above the pitching arm main body. And a stopper projection for preventing movement, and when the pitching arm is set to the “ball mounting posture”, when it is rotated at a high speed forward through the rotation shaft, it is mounted on the ball receiving groove. In the pitching arm structure in the baseball practice pitcher, the ball that has been placed rolls the ball receiving groove to the protruding end of the ball receiving portion and then throws forward.
The ball receiving portion includes position adjusting means that can adjust the position of the ball in the ball receiving groove in the throwing arm in the “ball placing posture”, and the position adjusting means is supported by the stopper protrusion. A nut and a bolt screwed onto the female thread of the nut on its axis, the shaft center extending substantially parallel to the ball receiving groove, and the bolt is rotated on the axis by twisting the bolt. It is possible to move, so that rolling of the ball placed in the ball receiving groove is blocked by the stopper projection via the bolt ,
A pair of left and right plate members on which the ball receiving portions are overlapped with each other, and a pair of plate members that form the stopper projections bulge outward from each other and extend substantially parallel to the ball receiving grooves. molding the swollen portion of the bead shape, throwing arm structure in baseball practice ball throwing machine you characterized in that by molding the internal thread of the nut between these two bulging portions. 2. The pitching arm structure for a baseball practice pitcher according to claim 1, wherein the axis passes through the vicinity of the center of a ball placed in the ball receiving groove. The pitching arm structure in the pitcher for baseball practice according to claim 1 , wherein a plurality of through holes are formed in the ball receiving portion.

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