Abstract:
A robot hand tool linkage device includes a locking mechanism and an actuation shaft driven between a lock position and a release position. A piston moves an actuation shaft upward and downward to cam outward a plurality push rods urging outward a plurality arc-shaped locking members. The locking members are captured under an arcuate surface of a tool plate which is thereby attached. A resilient member engages an outer groove in each of the locking members to urge them inward. When the outward force on the locking members is released, the resilient member moves the locking members inward to reduce their combined diameter sufficiently to disengage from the arcuate surface, and thereby to release the tool plate.

Description:
BACKGROUND OF THE INVENTION 
     1. Background of the Invention 
     The present invention relates to a tool linkage device for a robot hand. In particular, the present invention relates to a robot hand tool linkage device in which a plurality of radially provided rod members act as joining members for a locking mechanism which reliably connects a master plate and a tool plate. 
     2. Description of the Related Art 
     A robot hand tool linkage device selectively attaches and detaches several types of tools from a hand output part of a robot hand. Generally, robot hand tool linkage devices have an inner assembly (master plate) that is attached to a hand output part of a robot hand, an outer assembly (tool plate) onto which a tool is attached, and a locking mechanism which locks the inner assembly and outer assembly. 
     U. S. Pat. No. 4,696,524 discloses a robot hand tool linkage device that can rapidly connect and disconnect an inner assembly and an outer assembly. The locking mechanism for this robot hand tool linkage device has a piston member, a plurality of ball members acting as the joining members, and a ball receiver as a latching part. 
     The piston member is supported by the inner assembly and is slidable from a lock position to a lock release position. The ball member is housed and retained in a housing hole of an approximately cylindrical ball retainer which surrounds the outer perimeter of the output part of the piston member connected to the inner assembly. 
     The ball member can move in a direction which is perpendicular to the sliding direction of the piston member (henceforth referred to as the perpendicular direction). Consequently, with the housing hole of the ball retainer, its inner diameter side and outer diameter side are linked in the perpendicular direction, and the ball member moves in the perpendicular direction inside the housing hole. 
     The ball receiver is provided on the outer assembly. The ball receiver contacts the ball member on its tapered surface. During operation, when the piston member moves to the lock position, the ball receiver cooperates with the ball members to connect the inner assembly and the outer assembly. 
     For the ball retainer, a plurality of flat springs are provided along the outer perimeter surface of the ball retainer excluding the housing holes. Particularly when the inner assembly and outer assembly are being disconnected, the ends of adjacent flat springs assist in preventing the loss of ball members and urge the ball members toward the inner diameter of the ball retainer. 
     Japanese Laid-Open Patent Number 4-63688 provides a robot hand tool linkage device wherein a plurality of flat springs are on the outer perimeter surface of the ball retainer. The loss of ball members from the ball retainer is prevented by these flat springs. 
     Unfortunately, according to the robot hand tool linkage device described above, a plurality of flat springs are required to prevent the loss of ball members by impelling the ball members toward the inner diameter of the ball retainer. As a further detriment, the above designs require a large number of parts, and the structure is detrimentally complex, leading to higher manufacturing costs. 
     Since ball members are used as joining members, there is point contact or line contact between the spherical surface of the ball member and the flat surface of the ball receiver. The actual contact surface area is detrimentally small resulting in adversely high contact surface pressure. 
     Additionally, since the structure has a plurality of ball members placed along the entire perimeter, the contact parts between the ball member and the ball receiver is present only intermittently along the entire perimeter, and the contact surface pressure of the locking mechanism, as a whole, is detrimentally high. This high contact surface pressure results in substantially shortened mechanical life and reduces reliability. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a tool linkage device for a robot hand which overcomes the drawbacks of the related art described above. 
     It is another object of the present invention to provide a robot hand tool linkage device that reliably prevents the loss of the joining member, reduces the number of parts, simplifies the structure and design, reduces contact pressure between operable parts, maintains low manufacturing costs, and increases the durability of the device while retaining operational effectiveness. 
     The present invention relates to a robot hand tool linkage device that is equipped with a master plate that is connected to the output part of a robot hand, a tool plate onto which a tool is connected, and a locking mechanism that releasably locks the master plate and tool plate. 
     In particular, with the robot hand tool linkage device of the present invention, the locking mechanism comprises: an actuation shaft that is supported by the master plate and is driven between a lock position and a release position by an air cylinder inside the master plate; a ring-shaped retainer that is affixed to the master plate and that surrounds an outer perimeter of an output part of the actuation shaft; a plurality of rod insertion holes that are formed in an inner perimeter wall of the retainer and are formed penetrating in a radial direction that is perpendicular to a sliding direction of the actuation shaft; a ring-shaped groove that is formed on the retainer on an outer perimeter side of the plurality of rod insertion holes and that is formed with the outer perimeter side open; a plurality of push rods that are attached movably in the plurality of rod insertion holes and that transfer the output of the actuation shaft radially outward; and a plurality of arc-shaped locking members that are attached in a manner allowing for sliding in a radial direction in the ring-shaped groove and that are in contact with or are coupled with the ends of the push rods. 
     With this robot hand tool linkage device, when connecting the tool plate and the master plate, after positioning the master plate and the tool plate and forming a temporary connection, an actuator shaft is moved to a lock position by an air cylinder. Thereupon, each push rod is pushed radially outward, and a plurality of arc-shaped locking members slides radially outward where it and joins with the tool plate. With this, the tool plate and the master plate are securely locked. When releasing the connection between the tool plate and the master plate, the actuator shaft is moved to a lock release position by the air cylinder. Thereupon, the plurality of arc-shaped locking members moves to a smaller radius, and each push rod moves radially inward. Afterwards, when the pin connections and the like between the tool plate and the master plate are released, the connection between the tool plate and the master plate is completely released. 
     Other preferred constructions for the present invention are described in the preferred embodiments of the present invention. 
    
    
     The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cross-section of a tool linkage device of the present invention. 
     FIG. 2 is a partial cross-section of a tool linkage device in an actuation state of the locking mechanism. 
     FIG. 3 is a partial longitudinal cross-section of a different phase of the tool linkage device. 
     FIG. 4 is a longitudinal section of a different phase of the tool linkage device. 
     FIG. 5 is a horizontal section with an actuator shaft in a release position. 
     FIG. 6 is a horizontal section with the actuator shaft in a lock position. 
     FIG. 7 is a plan view of a push rod. 
     FIG. 8 is a front view of a push rod. 
     FIG. 9 is a partial expanded plan view of an arc-shaped locking member. 
     FIG. 10 is a cross-section along line X—X of FIG.  9 . 
     FIG. 11 is a cross-section along line XI—XI of FIG.  9 . 
     FIG. 12 is a longitudinal section of a tool linkage device in an alternative embodiment of the present invention. 
     FIG. 13 is a longitudinal section of FIG. 12 in an actuation state of the locking mechanism. 
     FIG. 14 is a horizontal section of the actuator shaft in a release position. 
     FIG. 15 is a horizontal section with the actuator shaft in a lock position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIGS. 1-4, a tool linkage device  1  for a robot hand includes a master plate  2  that connects to an output part H of a robot hand (not shown), a tool plate  3 , a locking mechanism which releasably locks together master plate  2  and tool plate  3 and an air cylinder  7 . During operation, one tool (not shown) from the multitude of possible tools (not shown) is connected to tool plate  3 . 
     Master plate  2  includes a master plate body  5  and a lid part  6 . Master plate body  5  is approximately cylindrical. A lid part  6  is affixed to an upper end of master plate body  5 . 
     A cylinder hole  8  of air cylinder  7  is formed in an upper half of master plate body  5 . A retainer joining hole  9 , which is larger in diameter than cylinder hole  8 , is formed on a lower half of master plate body  5 . A connector  10 , for securing electric wires (not shown) that power sensors and switches (not shown) on the tool(not shown) is provided at a side of master body plate  5 . 
     Air cylinder  7  is located in master plate  2 . A piston member  13 , of air cylinder  7 , is fitted in a sealed and slidable manner in cylinder hole  8 . Sets of seal members  11  and  12  retain pressure in air cylinder  7 , during operation. Seal member  13   a  slidably seals seal member  13  to cylinder hole  8 . 
     An actuator shaft  14  is affixed to a lower end of piston member  13 . Actuator shaft  14  extends-downwards and away from piston member  13 . During operation, actuator shaft  14  is raised and lowered by air cylinder  7  from a lock position (shown in FIG. 1) to a release position (shown in FIG.  2 ), as will be described. 
     A first actuation chamber  8   a , is formed in cylinder hole  8  in the lock position, between piston member  13  and lid part  6 . 
     A connection fitting  16 A, threadably joins master plate body  5 , for supplying and releasing pressurized air to first actuation chamber  8   a  via a passage hole  15 . 
     A second actuation chamber  8   b  consists of a lower part of cylinder hole  8  and an annular depression  17   a  in retainer  17 . A connection fitting  16 B, threadably joined to master plate body  5 , supplies and releases pressurized air from actuation chamber  8   b  through a passage hole  15 . In operation, pressurized air from a pressurized air supply source (not shown) is supplied to and released from air cylinder  7  by respective air hoses (not shown), connection fittings  16 A,  16 B, and passage holes  15 . 
     Tool plate  3  consists of an approximately cylindrical tool plate body  3   a  and a ring-shaped joining ring  21 , together with other elements. Ring-shaped joining ring  21  is placed inside a step part formed in the inner perimeter of the upper half of tool plate body  3   a . Joining ring  21  is affixed to tool plate body  3   a  by a plurality of bolts  22 . The inner surface of joining ring  21  includes a tapered joining surface  21   a  in which the inner diameter becomes smaller toward the top and a cylindrical surface  21   b  which extends downward from the lower end of tapered joining surface  21   a . A plurality of tapered pin holes  21   c  capable of joining with a plurality of tapered pins  28  (refer to FIG. 3) are formed on joining ring  21 . A connector  23  for the electric wires that power the sensors and switches of the tool and which connects with connector  10  is affixed to tool plate body  3   a.    
     In order to supply pressurized fluid of two systems, for example, of pressurized air and hydraulic pressure and the like to the tool side from the robot side, as shown in FIGS. 1-4, for example, four connection fittings  24 A- 24 D are provided near the outer surface of master plate body  5 . Four connection fittings  25 A- 25 D (only  25 B,  25 C are shown) corresponding to four connection fittings  24 A- 24 D are provided near the outer surface of tool plate body  3   a . When master plate  2  and tool plate  3  are connected, the upper and lower fluid passages are connected via a passage  26 . 
     Referring to FIGS. 1,  2 , and  5 - 11 , locking mechanism  4  has an actuator shaft  14  that is raised and lowered by air cylinder  7 , a ring-shaped retainer  17 , four rod insertion holes  18 , a ring-shaped groove  31 , four push rods  19 , and four arc-shaped locking members  20 . 
     The upper half of retainer  17  fits inside retainer joining hole  9  of master plate body  5 . Retainer  17  is secured to master plate body  5  by a plurality of bolts. Retainer  17  includes a plurality of tapered pins  28  that can fit into a plurality of pin holes  21   c  of joining ring  21 . On the inner perimeter side of the upper half of retainer  17 , a guide cylinder  29  that is formed in the shape of a cylinder surrounds the outside of the output part of actuation shaft  14 . A seal member  30  is also provided on guide cylinder part  29 . 
     A ring-shaped groove  31  on the lower half of retainer  17  is open on the outer perimeter side. A ring-shaped wall  17   b  is formed below ring-shaped groove  31 , and an inner perimeter wall  17   c  is formed to the inside of ring-shaped groove  31 . Inner perimeter wall  17   c  is a unitary continuation of guide cylinder  29 . Four rod insertion holes  18  are formed on inner perimeter wall  17   c , passing in a radial direction that is perpendicular to the sliding direction of actuator shaft  14 . Rod insertion holes  18  are formed at 90 degree intervals along the circumference. The outer perimeter end of ring-shaped wall  17   b  is slightly smaller in diameter than the inner perimeter surface of joining ring  21 . 
     A push rod  19  is carried in each rod insertion hole  18  free to move in the radial direction described above. In addition, push rod  19  is constructed so that the output of actuator shaft  14  is transmitted radially outward. 
     Referring to FIGS. 5-8, an inner end  19   a  of each push rod  19 , which receives the output of actuator shaft  14 , is a partial sphere. On the outer perimeter part of push rod  19 , four grease grooves  19   b  are formed in the radial direction at 90 degree intervals around the circumference. 
     Referring to FIGS.  1 , 2 ,  6  and  9 - 11 , four arc-shaped locking members  20  are attached to ring-shaped groove  31  in a manner that allows for sliding in the radial direction. A depression  20   e  is formed near the center of the arc in the inner perimeter part of each arc-shaped locking member  20 . The outer end of each push rod  19  loosely fits into a depression  20   e . The outer end of each push rod contacts depression  20   e . An arc groove  20   a  is formed on the outer perimeters of each of the four arc-shaped locking members  20 . A C-ring shaped spring member  32  is fitted into arc grooves  20   a . The four arc-shaped locking members are elastically urged toward a smaller radius by spring member  32 . A fastening hole  20   b  on one of the four arc-shaped locking members  20  fastening spring member  32  to its outer perimeter. 
     An arc-shaped joining surface  20   c  is formed near the outer perimeter of each arc-shaped locking member  20 . Arc-shaped joining surface  20   c  can join with tapered joining surface  21   a  of joining ring  21  and has a smaller radius toward the top. When actuation shaft  14  is at the lock position shown in FIG. 2, arc-shaped joining surfaces  20   c  of the four arc-shaped locking members  20  are in surface contact with and joins with tapered joining surface  21   a . When actuation shaft  14  is in the release position shown in FIG. 1, arc-shaped joining surface  20   c  has a smaller radius than tapered joining surface  21   a , thus permitting arc-shaped joining surface  20   c  to separate from tapered joining surface  21   a . A plurality of grease grooves  20   d  are formed on the upper and lower surfaces of each arc-shaped locking member  20 . Grease grooves  20   d  are formed at an equal spacing, and they extend a set length in the radial direction from the inner edge to the outer edge. 
     Although not shown in the figures, master plate  2  is coupled in advance with output part H of a robot hand. The desired tool is coupled in advance with tool plate  3 . Linkage tool plate  3  and master plate  2 , using the robot hand, are brought closer together. Their shaft centers and phases are aligned aided by engagement between the plurality of taper pins  28  on master plate  2  and the plurality of tapered pin holes  21   c  on tool plate  3 . Thus, master plate  2  and tool plate  3  are positioned to form a temporary linkage. 
     Next, referring to FIGS. 2 and 6, while releasing the air inside actuation chamber  8   b , pressurized air is introduced inside actuation chamber  8   a . This lowers and piston member  13  and actuation shaft  14  to the lock position. Thereupon, each push rod  19  is pushed outward in the radial direction by actuation shaft  14 , and the four arc-shaped locking members  20  slide radially outward. Each of the arc-shaped joining surfaces  20   c  joins with the tapered joining surface  21   a  of joining ring  21 . As a result, tool plate  3  is securely locked to master plate  2 . 
     Referring to FIGS. 1 and 5, for releasing the linkage between tool plate  3  and master plate  2 , pressurized air is introduced into actuation chamber  8   b  while the air inside actuation chamber  8   a  is released. Piston member  13  and actuation shaft  14  are raised to the lock release position. Thereupon, by the urging force of spring member  32 , the four arc-shaped locking members  20  move inward toward a smaller radius. Arc-shaped joining surfaces  20   c  of arc-shaped locking members  20  separate from the tapered joining surface  21   a  of joining ring  21 , and the linkage between tool plate  3  and master plate  2  is released. 
     In the prior art, a plurality of ball members as the joining member is placed over the entire perimeter. As a result of this construction, the contact portion between the ball member and the ball receiver is present only intermittently over the entire perimeter, and the contact surface pressure of the locking mechanism as a whole becomes high. However, with tool linkage device  1 , because a plurality of arc-shaped locking members  20  are used as the joining member, the contact portion between arc-shaped locking members  20  and tapered joining surface  21   a  is present almost continuously over the entire perimeter. As a result, the contact surface pressure of locking mechanism  4  as a whole is reduced. Therefore, the life span of locking mechanism  4  is lengthened, and the durability of the device is improved. 
     The plurality of push rods  19  are movably attached to the plurality of rod insertion holes  18 . The plurality of arc-shaped locking members  20  abutting ring-shaped groove  31  are elastically urged to a smaller radius by C-ring shaped spring member  32 . As a result, loss of push rods  19  or arc shaped locking members  20  from retainer  17  is reliably prevented. Therefore, the plurality of flat springs and the like used for preventing loss of the joining member in the prior art becomes unnecessary, the number of parts is reduced, and the construction is simplified. 
     Arc-shaped joining surface  20   c  formed on arc-shaped locking member  20  is capable of surface contact with tapered joining surface  21   a  of joining ring  21 . As a result, because its contact surface area is greatly increased compared with the contact surface area of the ball members in the prior art, the contact surface pressure required for secure attachment is reduced, and the durability of locking mechanism  4  is greatly improved. Therefore, the durability of robot hand tool linkage device  1  is greatly improved. 
     Next, a modification mode in which the present embodiment is partially modified is described. However, elements that are essentially the same as with the main embodiment described above are given the same numerals, and their descriptions are omitted. 
     1) The outer end of push rods  19  can be joined tightly with depression  20   e  of arc-shaped locking member  20 , they can be coupled by welding, or they can be coupled using adhesives or screws, and the like. When linkage push rod  19  with arc-shaped locking member  20 , depression  20   e  is not always necessary and may be omitted. 
     2) Referring to FIGS. 12-15, with tool linkage device  1 A, a surface contact part  35  is formed on the portion of push rod  19 A that contacts the output part of actuation shaft  14 . Surface contact part  35  makes surface contact with one portion of the surface of actuation shaft  14 . A pair of flat parts  36  is formed on the outer end portion of the outer perimeter surface of each push rod  19 . Using flat parts  36 , the outer end part of push rod  19 A is fitted inside and screws together with arc-shaped locking member  20 . 
     In other words, surface contact part  35  of push rod  19 A is in stable surface contact with one part of the surface of actuation shaft  14 . Otherwise, tool linkage device  1 A is constructed the same as the embodiment described above. According to tool linkage device  1 A, because push rod  19 A and actuation shaft  14  are in surface contact, the contact surface area is even larger than the embodiment described above, and the required surface contact pressure is further reduced. The durability of tool linkage device  1 A is further improved. 
     3) Each push rod and arc-shaped locking member can be formed unitarily. Push rod  19 A can be formed as a rod with a square cross-section. Piston member  13  and actuation shaft  14  can be formed unitarily. Joining ring  21  and tool plate body  3   a  can be formed unitarily. Fastening hole  20   b  of arc-shaped locking member  20  for fastening the spring member can be omitted. The number of push rods and their rod insertion holes is not limited to four, and, for example, can be three or more than four. The shape and placement and the like of the grease grooves of the push rods and the arc-shaped locking members can be changed. A lubricating agent other than grease can be coated in advance, or it can be supplied as needed. Various modifications may be effected therein without departing from the scope or spirit of the present invention. 
     Having described preferred embodiments of the invention with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the invention as defined in the appended claims.