DESCRIPTION MARKING TORQUE WRENCH Field 5 [0001] The present invention relates to a torque wrench capable of checking predetermined torque and, in particular, to a marking torque wrench capable of marking an object to be fastened when predetermined torque is reached in order to prevent the object to 10 be fastened from being forgotten to be fastened and prevent unnecessary retightening from being performed. Background [0002] 15 Various marking torque wrenches have been used conventionally in order to prevent an object to be fastened from being forgotten to be fastened or prevent unnecessary retightening of the object to be fastened which has been already fastened. Among these, there is a configuration example in which a mechanical marking mechanism 20 is incorporated into a torque wrench which detects that predetermined torque is reached by an operation of a toggle link provided between a thruster biased by a spring or the like, and aheadmember. As an example, amarking torque wrench which utilizes a movement of a thruster is shown in Fig. 9. 25 [0003] 1 7125660_1 (GHMatters) P101622.AU LYNT In a torque wrench 101 with a built-in marker in Fig. 9, an endofarod120, whichis disposed along a grip tube 104, is connected to a thrust member 106, and the other end thereof is connected to a link 122. In a socket 112 capable of housing an object 50 to be 5 fastened, on the other hand, a slide shaft 119 is inserted. A marking member 116 is provided in the slide shaft 119 and configured integrally with a sleeve 118 disposed so as to slide along an outer periphery of the socket 112. The link 122 is connected to the sleeve 118. Due to such a configuration, when predetermined torque is 10 reached in a fastening operation and the thrust member 106 is slightly pushed toward a head member 102 side, this movement is transferred via the rod and the link to push down the sleeve. Consequently, the provided marking member is lowered, which makes it possible to mark the object to be fastened. 15 Citation List Patent Literature [0004] Patent Literature 1: Japanese Utility Model Application 20 Laid-Open No. Hei. 2-78279 Summary Technical Problem [0005] 25 In the torque wrench 101 with the built-in marker as described 2 7125660_1 (GHMatters) P101622.AU LYNT above, however, the movement of the thrust member 106 is very small when the predetermined torque is generated. Therefore, while marking is easy when the object 50 to be fastened has a fixed shape (protrusion amount) like a bolt head, it is difficult to mark a 5 bolt protruding through a nut. [0006] In other words, in nut fastening work, a protrusion amount of a bolt differs depending on a thickness or size of the object to be fastened. Thus, it is necessary to transfer power in such 10 a manner that a sufficient stroke can be obtained on the side of the marking member 116. However, it is difficult to obtain the sufficient stroke since the movement of the thrust member 106 as a driving source is very small. [0007] 15 Moreover, it is also difficult to obtain a necessary and sufficient stroke on the side of the marking member 116 with respect to the bolts having different protrusion amounts. [0008] Accordingly, it is an object of the present invention to 20 provide a marking torque wrench capable of operating on the basis of a movement of a thrust member and stably marking a bolt protruding through a nut. Solution to Problem 25 [0009] 3 7125660_1 (GHMatters) P101622.AU LYNT In order to achieve the above-described object, a marking torque wrench of the present invention is provided with a toggle link connecting a head having a socket and a thruster biased from a rear end side of an operation rod and performs marking on the 5 basis of a movement of the thruster toward the head side, the marking torque wrench including: a stamp for marking; a stamp holder provided to slide along a fastening axis direction of the socket and holding the stamp with a stamp face facing a fastening operation side; a holder biasing means for biasing the stamp holder in a 10 direction away from the fastening operation side; a stamp biasing means for biasing the stamp inside the stamp holder so that the stamp face can advance toward the fastening operation side; a stay disposed along the operation rod, wherein one end of the stay is connected to the thruster; and a link mechanism provided between 15 the other end of the stay extending toward the head side and the stamp holder to transform a displacement of the thruster toward the head side to a displacement of the stamp holder toward the fastening operation side. [0010] 20 Moreover, in the marking torque wrench of the present invention, in addition to the above-described configuration, the link mechanism comprises an L-shaped stay pivotally supported at a bent position serving as a pivot point so as to rotate and having a short side connected to the stay and a long side extending to 25 a position to contact an end of the stamp holder opposite to the 4 7125660_1 (GHMatters) P101622.AU LYNT fastening operation side. [0011] Moreover, in the marking torque wrench of the present invention, in addition to the above-described configuration, the 5 stamp holder includes an opening formed on the fastening operation side and is a tubular member provided with a spring receiver formed in a protruding manner on an outer peripheral surface thereof. The holder biasing means is a first coil spring for biasing the spring receiver so as to be away from the fastening operation side. The 10 stamp includes a shoulder part provided in a protruding manner in the vicinity of the stamp face so as to engage with an inner peripheral edge of the opening of the stamp holder. The stamp biasing means is a second coil spring for biasing the stamp toward the fastening operation side. 15 [0012] Moreover, in the marking torque wrench of the present invention, in addition to the above-described configuration, the socket includes a regular hexagonal housing part formed on the fastening operation side and further includes a resin cap which 20 can be attached to and detached from the socket, having an outer peripheral surface formed with six outer flat faces which can be brought into internal contact with inner six faces on the fastening operation side and six curved faces each of which is continuously formed between the outer flat faces adjacent to each other in such 25 amanner that a distance from a center to the curved face is slightly 5 7125660_1 (GHMatters) P101622.AU LYNT larger than a distance between the center and the outer flat face, and including an ink holding member, which can abut against the stamp face, provided in a recessed part formed in one end thereof. 5 Advantageous Effects of Invention [0013] As described above, according to the present invention, when predetermined torque is reached, the stay moves toward the head side along the operation rod on the basis of the displacement of 10 the thruster toward the head side, and then the stamp holder is pushed toward the fastening operation side against the biasing of the stamp biasing means by the link mechanism connected to the stay. Consequently, the stamp face exposed outside the stamp holder toward the fastening operation side abuts against the object to be fastened 15 and thereby performs marking thereon. [0014] When the stamp face is exposed outside the stamp holder toward the fastening operation side, the stamp is being biased toward the fastening operation side. Therefore, in a case that the protrusion 20 amount of the stamp from the stamp holder is too much with respect to the object to be fastened, the stamp can be retracted into the stamp holder against the stamp biasing means. Thus, an excess protrusion amount can be absorbed. [0015] 25 Moreover, according to the present invention, in addition to 6 7125660_1 (GHMatters) P101622.AU LYNT the above-described effect, a slight movement of the thruster is amplified and thus reflected in a movement of the stamp holder in the fastening axis direction since the L-shaped stay used to constitute the link mechanism is disposed in such a manner that 5 the short side thereof is connected to the stay connected to the thruster and the long side thereof contacts the end of the stamp holder opposite to the fastening operation side, and is pivotally supported so as to rotate at the bent position. [0016] 10 Thus, as the stroke of the stamp holder is increased, even when protrusion amount of objects to be fastened vary, marking can be stably performed. [0017] Moreover, according to the present invention, the first coil 15 spring is disposed along the outer peripheral surface of the stamp holder as the holder biasing means and the second coil spring is employed as the stamp biasing means, wherein the /coil springs having different winding diameters can be used in combination. Consequently, in addition to the above-described effects, the two 20 biasing means can be provided in a space-saving manner. [0018] Moreover, according to the present invention, the outer peripheral surface of the resin cap is formed by alternately arranging the six outer flat faces which can be brought into contact 25 with the regular hexagonal inner surface of the socket and the curved 7 7125660_1 (GHMatters) P101622.AU LYNT faces each connecting the outer flat faces adjacent to each other, and the curved face is formed so as to protrude toward the outer diameter side slightly more than the outer flat face. Thus, when the resin cap is rotated about the fastening axis after being 5 inserted in such a manner that the outer flat faces are kept alongside the inner surface of the socket, the curved faces are crushed with elastic deformation of the resin, and the outer peripheral surface of the cap is brought into pressure contact with the inner surface of the socket. Consequently, in addition to the 10 above-described effects, the cap is held stably. Further, as the ink holding member is provided in the recessed part formed at the one end of the resin cap , the stamp face can be protected with ink being applied thereto simply by inserting the resin cap. 15 Brief Description of Drawings [0019] Fig. 1 is a side cross-sectional view illustrating an internal structure of a marking torque wrench according to an embodiment 20 of the present invention. Fig. 2 is a top cross-sectional view illustrating the internal structure of the marking torque wrench in Fig. 1. Fig. 3 is an overall perspective view illustrating the marking torque wrench in Fig. 1. 25 Fig. 4 is an enlarged cross-sectional view illustrating the 8 7125660_1 (GHMatters) P101622.AU LYNT vicinity of a head in Fig. 1. Fig. 5 shows operational states of the marking torque wrench in Fig. 1 wherein Fig. 5(a) is an enlarged cross-sectional view illustrating a state when a protrusion amount of a bolt is 5 relatively large and Fig. 5 (b) is an enlarged cross-sectional view illustrating a state when a protrusion amount of a bolt is relatively small . Fig. 6 is a perspective view illustrating a resin cap of the marking torque wrench according to the embodiment of the present 10 invention. Fig. 7 is an enlarged cross-sectional view illustrating a state of the resin cap in Fig. 6 being attached to the marking torque wrench in Fig. 1. Fig. 8 shows enlarged views illustrating attached states of 15 the resin cap in Fig. 6 as viewed from a socket side wherein Fig. 8(a) is a diagram illustrating a state of outer flat faces being put alongside an inner surface of the socket and Fig. 8(b) is a diagram illustrating a state of curved faces being pressed against the inner surface of the socket. 20 Fig. 9 is a cross-sectional view illustrating a conventional torque wrench with a built-in marker. Description of Embodiments [0020] 25 A marking torque wrench according to an embodiment of the 9 7125660_1 (GHMatters) P101622.AU LYNT present invention will be described below with reference to the drawings. An overall configuration of a marking torque wrench 1 will be described with reference to Figs. 1 to 3, and a configuration in the vicinity of a head 2a of a head member 2 will be described 5 in detail with reference to Fig. 4. Moreover, operations of the marking torque wrench 1 will be described with reference to Fig. 5. A configuration of a resin cap 30 and states of its use will be described with reference to Figs. 6 to 8. [0021] 10 Fig. 1 is a cross-sectional view illustrating the entire marking torque wrench 1 as viewed from a side thereof in order to clearly show an internal structure thereof. Moreover, Fig. 2 illustrates the marking torque wrench 1 in Fig 1 in a planar view. As with Fig. 1, Fig. 2 illustrates the entire marking torque wrench 15 1 with a cross-sectional view in order to clearly show the internal structure thereof. [0022] As shown in Figs. land 2, the marking torque wrench 1 according to the present embodiment is provided with a biasing spring 8 on 20 a rear end side thereof. A thruster 6 is biased toward a head side by the biasing spring 8. The thruster 6 is connected to a head shaft 2b of the head member 2 via a toggle link 10 so as to transfer a biasing force to the head 2 side. With such a configuration, when predetermined torque is reached in a fastening operation, the 25 thruster 6 is pushed back toward the rear end side against the 10 7125660_1 (GHMatters) P101622.AU LYNT biasing of the biasing spring 8. [0023] In the present embodiment, an end of a stay 20 on the rear end side is connected to the thruster 6, wherein the stay 20 is 5 disposed along an operation rod 4connected. As is apparent in Fig. 2, the stay 20 and a toggle 10a are connected to the thruster 6 with a common connecting shaft 21. Moreover, the operation rod 4 is provided with an oblong hole formed in a surface thereof in a non-fastening operation side so that the connecting shaft 21 can 10 follow a movement of the thruster 6. [0024] An end of the stay 20 on the head 2a side is connected to a short side 22a of an L-shaped stay 22. The L-shaped stay 22 is pivotally supported at a bent part 22c so as to rotate. With 15 reference to Fig. 3, this pivotally-supporting structure is described. Fig. 3 is a perspective view illustrating the entire marking torque wrench 1. In Fig. 3, an exploded view illustrating a cover 23 for protecting the L-shaped stay 22 being detached therefrom is shown with solid lines and a state illustrating the 20 cover 23 being attached thereto is shown with alternate long and two short dashed lines. As can be seen in Fig. 3, the L-shaped stay 22 is pivotally supported at the bent part 22c by two supports 25 therebetween. [0025] 25 A long side 22b of the L-shaped stay 22 extends toward the 11 7125660_1 (GHMatters) P101622.AU LYNT head 2a side, and a tip thereof reaches a marking mechanism 15. The marking torque wrench 1 according to the present embodiment is provided with the marking mechanism 15 above a socket 12 for housing a bolt 51 and a nut 52 (described later) of an object to 5 be fastened. The marking mechanism 15 is provided with a tubular cover body 17 as an outer covering. As shown in Fig. 1, a stamp holder 18 is provided inside the cover body 17 so as to slide in a direction of a fastening axis A. [0026] 10 With reference to Fig. 4, a detailed configuration of the marking mechanism 15 is described. Fig. 4 is an enlarged cross-sectional view illustrating the vicinity of the head 2a of the marking torque wrench 1. The stamp holder 18 is provided above the socket 12 so as to slide along an inner surface of the socket 15 12. A spring receiver 18c is provided on an outer peripheral part of the stamp holder 18 in the non-fastening operation side. A coil spring 26 (a first coil spring) is disposed between the spring receiver 18c and an end of the socket 12 in the non-fastening operation side. The stamp holder 18 is biased toward the 20 non-fastening operation side (in a direction away from a housing part in the fastening axis direction) by the coil spring 26 and thus held up above the socket 12. [0027] A stamp 16 is disposed inside the stamp holder 18 in such a 25 manner that a stamp face 16a faces toward the fastening operation 12 7125660_1 (GHMatters) P101622.AU LYNT side. As can be seen in Fig. 4, an opening 18b is formed in a lower side (fastening operation side) of the stamp holder 18. The stamp face 16a of the stamp 16 is disposed so as to be exposed toward the fastening operation side outside the opening. A shoulder part 5 16b, having a diameter larger than that of the opening 18b of the stamp holder 18, is formed in the vicinity of the stamp face 16a. Thus, the shoulder part 16b gets caught in the stamp holder 18. A coil spring 28, which is smaller than the coil spring 26, is disposed above the stamp 16. A holder screw 18d closes an upper 10 part of the stamp holder 18 so as to compress the coil spring 28. Thus, the stamp 16 is biased toward the fastening operation side of the socket 12. In this manner, the coil spring 26 is provided as a stamp holder biasing means and the coil spring 28 is provided as a stamp biasing means. 15 [0028] The tubular cover body 17 is opened in the rear end side, and the L-shaped stay 22 enters the tubular cover body 17in such a manner that an end of the long side 22b is brought into contact therewith. [0029] 20 With the configuration as described above, when fastening torque reaches or exceeds a specified value in a fastening operation, the stay 20 is pulled toward the rear end side by the thruster 6, and the short side 22a of the L-shaped stay 22 is also pulled toward the rear end side. Consequently, force to push the 25 holder screw 18d is generated on the long side 22b of the L-shaped 13 7125660_1 (GHMatters) P101622.AU LYNT stay 22. Subsequently, this operation will be described with reference to Fig. 5. 5 [0030] Fig. 5 shows a comparison between two operational states of the marking torque wrench 1. Fig. 5(a) shows an operational state when the bolt 51 is relatively long, whereas Fig. 5(b) shows an operational state when the bolt 51 is relatively short. As can be 10 seen in Fig. 5(a), when the bolt 51 is relatively long, the stamp face 16a abuts against the bolt 51 in an inner side of the socket 12. However, a rotated angle of the L-shaped stay 22 is constant since the rotated angle depends on a travel distance of the thruster 6 (see Fig. 1) . In this case, the long bolt 51 is accommodated with 15 the coil spring 28 being compressed a lot. In the state shown in Fig. 5 (b), on the other hand, as the bolt 51 is not as long as that in Fig. 5(a), the stamp face 16a abuts against the bolt 51 somewhat in an outer side in the socket 12. Accordingly, a coil width 28a shown in Fig. 5(b) is larger than the coil width 28a of the coil 20 spring 28 shown in Fig. 5(a). Since a coil width 26a of the coil spring 26 disposed around an outer periphery of the stamp holder 18 is less influenced by external force than the smaller coil spring 28, there is little difference between these states in the coil width 26a. 25 [0031] 14 7125660_1 (GHMatters) P101622.AU LYNT Thus, in the marking torque wrench 1 according to the present embodiment, difference in the protrusion amount of the bolt 51 can be absorbed by the coil spring 28. Accordingly, a marking operation canbe always performed in a stablemanner independent ofa thickness 5 or size of a fastened member sandwiched between a bolt head of the bolt 51 and the nut 52. [0032] Fig. 6 shows the resin cap 30 capable of covering the housing part of the socket 12 of the marking torque wrench 1 according to 10 the present embodiment. As shown in Fig. 6, the resin cap 30 has six outer flat faces 30a formed on an outer peripheral surface thereof. The resin cap 30 is formed in a size such that the six outer flat faces 30a can contact an inner peripheral surface of the socket 12. A curved face 30b is formed between the outer flat 15 faces 30a adjacent to each other. In this manner, the six outer flat faces 30a and the six curved faces 30b are combined alternately to form the outer peripheral surface of the resin cap 30. In Fig. 6, a boundary between the outer flat face 30a and the curved face 30b is indicated by an alternate long and short dashed line in order 20 to clearly show such a configuration. As is apparent in Fig. 6, a recessed part 30c is formed in one end of the resin cap 30. An ink holding member 32 is provided in the recessed part 30c. A state of the resin cap 30 being attached to the socket 12 is shown in Fig. 7. 25 [0033] 15 7125660_1 (GHMatters) P101622.AU LYNT As shown in Fig. 7, the recessed part 30c of the resin cap 30 is formed in approximately the same diameter as that of the stamp surface 16a. Thus, as the resin cap 30 is inserted into the socket 12, the stamp face 16a of the stamp 16 is to be inserted into the 5 recessed part 30c. At this time, since the stamp face 16a abuts against the ink holding member 32 in the recessed part 30c, ink is applied to the stamp face 16a. Thus the stamp face 16a can be protected and prevented from being dried. [0034] 10 Fig. 8 shows states of the resin cap 30 being attached to the socket 12 as viewed from a side of an opening of the socket 12 for housing. Fig. 8 (a) shows a state in which the outer flat faces 30a of the resin cap 30 are in contact with the inner surface of the socket 12. Fig. 8 (b), on the other hand, shows a state in which 15 the curved faces 30b of the resin cap 30 are pressed against the inner surface of the socket 12. [0035] In Fig. 8, in order to clearly show the arrangements of the resin cap 30 inserted into the socket 12, a certain curved face 20 30b and the center are connected with an alternate long and short dashed line. As can be seen in this figure, while the state in Fig. 8 (a) changes to the state in Fig. 8 (b), the resin cap 30 is to be rotated by 30 degrees about the fastening axis (see Fig. 3). The resin cap 30 according to the present embodiment is formed to have 25 the curved faces 30b to protrude more than the outer flat faces 16 7125660_1 (GHMatters) P101622.AU LYNT 30a in a radial direction thereof as described above. Accordingly, when the resin cap 30 is inserted with the outer flat faces 30a being kept alongside the inner surface of the socket 12 and rotated about the fastening axis, the curved faces 30b are pressed against 5 the inner surface of the socket 12 with elastic deformation of the resin. Consequently, the resin cap 30 can be stably held inside the socket 12. In Fig. 8 (b), pressure from the curved faces 30b is applied to respective six portions indicated by arrows. [0036] 10 Although the above embodiment shows, by way of an example, the configuration in which the coil springs are used as the holder biasing means and the stamp biasing means, the biasing means are not limited to such coil springs, but other elastic members such as a flat spring may be employed as the biasing means. 15 [0037] Although the above-described embodiment shows, by way of an example, the configuration in which the single L-shaped stay is used as a link mechanism for transferring power from the stay to the stamp holder, the link mechanism is not limited to such a single 20 L-shaped stay, but a link comprising a plurality of members may be employed as long as the link can amplify the power from the stay to obtain a sufficient stroke of the stamp holder. [0038] Although the above-described embodiment illustrates the 25 configuration of the torque wrench including a ratchet mechanism, 17 7125660_1 (GHMatters) P101622.AU LYNT the torque wrench may not include the ratchet mechanism. [0039] Moreover, as an example of the curved faces constituting the outer peripheral surface of the resin cap, the above-described 5 embodiment shows the curved face formed of a smooth curved surface protruding in an outer diameter direction with no inflection point. However, the curved face may be formed in a shape having a plurality of inflection points such as a wave shape as long as the curved face has a shape protruding toward the outer diameter side more 10 than the outer flat face. Furthermore, the curved face may not have a uniform shape in a longitudinal direction thereof. The similar effect can be obtained as long as a region to be inserted into the socket is formed with a portion protruding toward the outer diameter side more than the outer flat face. 15 Reference Signs List [0040] 1 marking torque wrench 2 head member 20 2a head 2b head shaft 4 operation rod 4a oblong hole 6 thruster 25 8 biasing spring 18 7125660_1 (GHMatters) P101622.AU LYNT 10 toggle link 10a toggle 12 socket 12a housing part 5 12b ratchet tooth 14 switching part 14a ratchet pawl 15 marking mechanism 16 stamp 10 16a stamp face 16b shoulder part 17 cover body 18 stamp holder 18a outer peripheral surface 15 18b opening 18c spring receiver 18d holder screw 20 stay 21 connecting shaft 20 22 L-shaped stay (link mechanism) 22a short side 22b long side 22c bent part 23 cover 25 24 pivot point (link mechanism) 19 7125660_1 (GHMatters) P101622.AU LYNT 25 support 26 coil spring (first coil spring, holder biasing means) 26a coil width 28 coil spring (second coil spring, stamp biasing means) 5 28a coil width 30 resin cap 30a outer flat face 30b curved face 30c depressed part io 32 ink holding member 51 bolt (object to be fastened) 52 nut (object to be fastened) 20 7125660_1 (GHMatters) P101622.AU LYNT