JP6868308B2 - Vacuum suction arm and collet - Google Patents

Description

The present invention relates to a vacuum suction arm and a collet provided at the tip of the vacuum suction arm, which are constituent members of a precision processing apparatus that vacuum-sucks and operates fine members such as electronic parts.

A precision processing device such as a mounting machine for assembling electronic parts is provided with a vacuum chuck mechanism (vacuum suction arm) such as a vacuum tweezers for vacuum suctioning an object to be operated at the tip of the precision processing device. By creating a negative pressure in the hollow portion inside the device, the object to be operated can be evacuated, and by creating a positive pressure, the object to be operated can be detached and attached to an arbitrary position. The tip shape of the nozzle head (collet) provided at the tip of the vacuum suction arm is precisely designed to fit the object to be operated, and is a consumable item that wears and breaks with each use. Further, the nozzle tip of the collet or the tip of the collet must be replaced as appropriate depending on the type of the object to be operated. Therefore, it is common that at least one of the vacuum suction arm and the collet has a mechanism for temporarily fixing the collet to the vacuum suction arm and replacing it as appropriate.

Therefore, the upper part of the collet 34 is inserted into the lower part of the collet insertion hole provided at the tip of the arm portion forming the vacuum suction arm, and the upper part of the collet is a fixing screw screwed from the side portion of the collet mounting portion. A structure screwed by is proposed (see Patent Document 1). That is, the collet described in Patent Document 1 has an insertion portion which is an upper portion to be inserted into the collet insertion hole, a large diameter portion having a larger diameter than the insertion portion, and a tapered portion extending downward from the large diameter portion. It is formed by a nozzle tip, and the collet is formed with a vacuum through hole as a suction hole that penetrates vertically and communicates with the collet insertion hole.

A collet has also been proposed in which the insertion portion into the collet insertion hole is provided with a slit whose depth direction is the central axis direction to impart elasticity. This slit is cut in a U shape downward from the upper end of the insertion portion, and has a spring-like structure in which the shape of the insertion portion is divided into two parts. The diameter of the collet insertion part is designed to be slightly larger than the diameter of the collet insertion hole, and when the collet insertion part is inserted into the collet insertion hole, the part separated by the slit is slightly on the slit side and the central axis side. Since the diameter becomes smaller by approaching, the collet can be inserted into the collet insertion hole. After insertion, the elastic repulsive force that causes the slit-separated portion to return to its original shape acts outward, and the collet is firmly fixed to the collet insertion hole. There is an advantage that the collet can be inserted and removed with one touch by applying a certain force.

However, in this conventional technique, both the through hole penetrating the central axis direction of the collet having a fine shape and the slit of the insertion portion having a fine shape must be machined with high precision. Since the slit provided in the insertion portion is partially continuous with the through hole involved in the suction / detachment function of the object to be operated, it depends on the width of the slit or the length in the central axis direction of the slit. It may affect the adsorption function of the object. In addition, a problem may occur in terms of the fixing force to the main body of the precision processing apparatus. Therefore, processing of through holes and slits requires delicate precision processing technology, and there is a problem that the collet itself, which is a replacement part, becomes expensive.

Japanese Unexamined Patent Publication No. 2000-114582

The present invention has been made by paying attention to the above problems, and is a vacuum suction arm capable of inserting and removing the collet at the tip with one touch and strengthening the holding force of the collet without causing compression cracking of the O-ring. It is an object of the present invention to provide a collet which is a component of a vacuum suction arm.

In order to achieve the above object, the first aspect of the present invention is (a) to form a first tubular shape surrounding the vacuum suction hole, and to form the first and second inner peripheral grooves in a first tubular shape. Arm shafts provided parallel to each other on the inner peripheral surface and (b) a part of each are fitted into the first and second inner peripheral surface grooves, and a part of each remaining part is evacuated from the inner peripheral surface. The outer peripheral surface was defined by the first and second O-rings (O-rings) protruding toward the central axis of the suction hole, and (c) a holding surface having an outer diameter smaller than the inner peripheral surface diameter. It has a convex part for holding at the tip, is continuous with the convex part for holding, has a wide groove with a diameter smaller than the convex part for holding, and has a concavo-convex second tubular shape, and is provided parallel to each other at the bottom of the wide groove. The gist is that the vacuum suction arm is provided with a collet having first and second outer peripheral groove. In the vacuum suction arm according to the first aspect, when the upper part of the collet is inserted into the lower part of the arm shaft, the first and second O-rings are held in the first and second outer peripheral surface grooves, respectively.

In the second aspect of the present invention, the first tubular shape surrounding the vacuum suction hole is formed, and the first and second inner peripheral surface grooves are provided on the first tubular inner peripheral surface so as to be parallel to each other. The tip has a holding convex portion whose outer peripheral surface is defined by a holding surface having an outer diameter smaller than the diameter of the inner peripheral surface, which is inserted into the arm shaft, and is continuous with the holding convex portion and has a holding convex portion. The present invention relates to a second tubular collet having an uneven shape having a wide groove having a diameter smaller than that of the portion. The gist of the collet according to the second aspect is that the collet has first and second outer peripheral surface grooves provided parallel to each other at the bottom of the wide groove. Similar to the vacuum suction arm according to the first aspect, a part of each of the first and second O-rings is fitted into the first and second inner peripheral groove, and a part of the remaining portion of each is fitted to the inner circumference. When the upper part of the collet is inserted into the lower part of the arm shaft in a state where it protrudes from the surface toward the central axis of the vacuum suction hole, the first and second O-rings are placed in the first and second outer peripheral surface grooves, respectively. Be retained.

According to the aspect of the present invention, a vacuum suction arm capable of inserting and removing the collet at the tip with one touch and strengthening the holding force of the collet without causing compression cracking of the O-ring, and a collet which is a component of the vacuum suction arm. Can be provided.

1 (a) is a front view of the vacuum suction arm according to the embodiment of the present invention, FIG. 1 (b) is a cross-sectional view taken from the direction AA of FIG. 1 (a), and FIG. 1 (c). ) Is an enlarged view of a portion B in FIG. 1 (b). FIG. 5 is an enlarged cross-sectional view showing a part of the collet shown in FIG. 1 (c). FIG. 2 is an enlarged cross-sectional view showing a part of a collet of a vacuum suction arm according to a reference example of the present invention, which corresponds to FIG. It is an enlarged cross-sectional view which excerpted the arm shaft 11 of FIG. 1C. It is sectional drawing which shows a part of the collet of the vacuum suction arm which concerns on a reference example corresponding to FIG. 3 in a wider range. It is an enlarged cross-sectional view of the lower part of the arm shaft which concerns on a comparative example. It is an enlarged cross-sectional view of the upper part of the nozzle tip which concerns on a comparative example. It is a bird's-eye view of FIG. 1 (a). It is a figure explaining the problem and effect when the crushing rate of O-ring is changed. It is sectional drawing which shows the part of the collet of the vacuum suction arm which concerns on a comparative example enlarged.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings below, the same or similar parts are designated by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the plane dimensions, the ratio of the sizes of each member, etc. are different from the actual ones. Therefore, the specific thickness, dimensions, size, etc. should be judged more diversely in consideration of the purpose of the technical idea that can be understood from the following explanation. In addition, it goes without saying that the drawings include parts having different dimensional relationships and ratios from each other.

Further, the embodiments of the present invention shown below exemplify an apparatus for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, and the like of the component parts. The arrangement etc. is not specified to the following. The technical idea of the present invention is not limited to the contents described in the embodiments of the present invention, and various modifications can be made within the technical scope specified by the claims described in the claims. ..

(Embodiment)
As shown in FIGS. 1 (a) and 1 (b). The vacuum suction arm according to the embodiment of the present invention is a collet in which an upper insertion portion is inserted into a first tubular arm shaft 11 and a lower portion of a vacuum suction hole 13 penetrating the tubular axis direction of the arm shaft 11. 31 is provided. As shown in FIG. 1 (c), a ring-shaped first inner peripheral groove (outer diameter side ring groove) 15 and a second inner peripheral groove (outer diameter side ring groove) are formed in the lower portion of the inner wall of the arm shaft 11. 17 has cylindrical grooves carved parallel to each other. A first O-ring (O-ring) 21 and a second O-ring 23 made of an elastic body are arranged in each of the first inner peripheral surface groove 15 and the second inner peripheral surface groove 17. In FIG. 1C, the first inner peripheral groove 15 and the second inner peripheral groove 17 are exemplified as square grooves, but the first O-ring 21 and the second O-ring 23 are effective in preventing popping out. The first inner peripheral groove 15 and the second inner peripheral groove 17 may be formed by the groove. Although not shown in FIG. 1 (c), it goes without saying that the corners of the first inner peripheral groove 15 and the second inner peripheral groove 17 may be subjected to R chamfering (curved surface processing). Is.

As shown in FIG. 1 (c), the collet 31 has a hollow tubular shape having a through hole 33 penetrating in the central axial direction. As shown in FIG. 1 (c), the collet 31 is provided with a wide groove 35 so as to surround the outer peripheral surface of the upper insertion portion. The width of the wide groove 35 may be such that the first O-ring 21 and the second O-ring 23 fit in the wide groove 35 in a state where the insertion portion of the collet 31 is inserted into the arm shaft 11. A stopper 37 is provided on the outer peripheral surface of the insertion portion below the wide groove 35. The stopper 37 is a ring-shaped holding convex portion, and constitutes a large diameter portion having a larger diameter than the insertion portion of the collet 31. When the collet 31 is inserted into the arm shaft 11, the stopper 37 having a large diameter is buffered and held by the stopper receiving portion 19 provided at the inner edge of the opening at the lower end of the arm shaft 11. To. The stopper 37 has a function of determining the insertion depth of the insertion portion of the collet 31 at the time of insertion. In FIG. 1 (c), the stopper 37 and the stopper receiving portion 19 have a continuous uniform ring shape, but in order to further have a function of determining the rotation position, the collet 31 and the arm shaft 11 are on the circumference. It is also possible to install it intermittently in a part.

FIG. 5 shows a collet 31 according to a reference example having a second tubular shape having a diameter smaller than the diameter of the inner peripheral surface of the vacuum suction hole 13. On the outer peripheral surface of the upper insertion portion of the collet 31 according to the reference example, the first inner diameter side ring groove (first outer peripheral surface groove) OG ₁₂ and the second inner diameter side ring groove (second outer peripheral surface groove) OG are formed in a ring shape. ₁₁ are provided parallel to each other. FIG. 2 shows an enlarged view of a portion of the collet 31 shown in FIG. 5 _{corresponding to the first outer peripheral surface groove OG 12.} Generally, in the case of a rod seal, only the first inner peripheral groove 15 and the second inner peripheral groove 17 are provided as cylindrical grooves on the inner wall of the arm shaft 11, and in the case of a piston seal, the outer peripheral surface of the collet 31 is provided. , Only the first outer peripheral groove OG ₁₂ and the second outer peripheral groove OG ₁₁ are provided as cylindrical grooves. However, in the vacuum suction arm according to the embodiment, the first outer peripheral surface groove OG ₁₂ is provided on the outer peripheral surface of the collet 31 facing the first inner peripheral surface groove 15 of the arm shaft 11, and the second inner surface of the arm shaft 11 is provided. The feature is that the second outer peripheral groove OG ₁₁ is provided as a cylindrical groove facing the peripheral groove 17.

In FIG. 1 (c), the first O-ring 21 is fitted in the first inner peripheral surface groove 15, and the second O-ring 23 is fitted in the second ring 17. The first O-ring 21 and the second O-ring 23 are torus bodies, which are toruses filled with contents, respectively, and have a shape obtained by rotating a circular cross section shown in FIG. 1 (c). A part of the first O-ring 21 protrudes from the first inner peripheral surface groove 15 and constitutes a curved holding convex portion from the position of the inner peripheral surface of the arm shaft 11 toward the central axis of the vacuum suction hole 13. Similarly, a part of the second O-ring 23 protrudes from the second inner peripheral surface groove 17 and forms a curved holding convex portion from the position of the inner peripheral surface of the arm shaft 11 toward the central axis of the vacuum suction hole 13. ing. In the cross-sectional view of FIG. 1C, the first inner peripheral groove 15 and the second inner peripheral groove 17 are U-shaped, but the first O-ring 21 and the second O-ring 23 are respectively. Other shapes such as U-shape and V-shape may be used as long as they can be fitted. The arm shaft 11, the first O-ring 21, and the second O-ring 23 form a collet holding portion (11, 1, 2, 23).

In FIG. 2, d ₀ is the minimum diameter of the collet 31 at the bottom surface of the first outer peripheral groove OG ₂₂ and the second outer peripheral groove OG _{21 , and d 1} is the wide groove 35 without the first outer peripheral groove OG _12. The diameter of the collet 31 on the surface. In FIG. 2, the guide portion outer diameter d ₃ indicates the diameter of the collet 31 on the _{holding surface S 2} without the wide groove 35. Holding surface S ₂ includes a holding inclined surface S ₃ that is continuous with the holding surface S ₂ constitutes the inclined surface of the V-grooves of the first outer peripheral surface groove OG _12, the holding surface S ₂ in opposition to the holding inclined surface S ₃ surrounded by the insertion inclined surface S ₁ consecutive.

The insertion pressure when the collet 31 is inserted into the first O-ring 21 fixed to the first inner peripheral groove 15 of the arm shaft 11 and the second O-ring 23 fixed to the second inner peripheral groove 17. In order to make it smaller, the insertion angle θ _{i formed by the insertion inclined surface S 1} and the inner wall surface S ₄ of the through hole 33 should be selected in the range of 22 to 33 °, particularly in the range of 24.5 to 25.5 °. preferable. The insertion angle θ _i is a chamfer angle corresponding to a guide angle for inserting the tip of the collet 31 into the first O-ring 21 and the second O-ring 23 when the collet 31 is inserted into the arm shaft 11.

In the vacuum suction arm according to the embodiment, the first O-ring 21 and the second O-ring 23 are not for the purpose of simply maintaining the sealing property such as a vacuum seal, but after obtaining the holding force for holding the collet 31 on the arm shaft 11. _{Since the purpose is the insertion / extraction durability and the ease of insertion / extraction, the first outer peripheral surface groove OG 22} and the first outer peripheral surface groove OG 22 of the collet 31 and the inner diameter of the first O-ring 21 and the second O-ring 23 in the state where the collet 31 is not inserted. the minimum diameter _{d 0} of the second outer peripheral surface grooves _{OG 21} is increased, compression rate epsilon ₂ of the first O-ring 21 of the compression rate epsilon ₁ and a second O-ring 23 is selected in each of 17 to 19%.

The crushing rates ε ₁ and ε ₂ of the first O-ring 21 and the second O-ring 23 depend on the hardness (hardness) of the first O-ring 21 and the second O-ring 23, but the hardness (durometer hardness). ) Is 70 to 90 degrees, it is set to 15 to 25%. The crushing rate ε ₁ of the first O-ring 21 is a value obtained by dividing _{the crushing allowance δ 1} of the first O-ring 21 by the wire diameter (thickness) D _{1 of the first O-ring 21:}

ε ₁ = δ ₁ / D ₁ × 100 …… (1)

Similarly, the crushing rate ε ₂ of the second O-ring 23 is a value obtained by dividing _{the crushing allowance δ 2} of the second O-ring 23 by the wire diameter D _{2 of the second O-ring 23:}

ε ₂ = δ ₂ / D ₂ × 100 …… (2)

As shown in FIG. 9, in the case of a fluorine-based rubber-based O-ring, if the crushing rates ε ₁ and ε ₂ are set to 30% or more, it becomes difficult to insert the collet 31 into the arm shaft 11.

In the case of a fluorine-based rubber-based O-ring, a crushing allowance of about 8% is sufficient for the purpose of simply maintaining the sealing property. As a result of trial and error, the present inventors have found that when the O-ring crushing rate exceeds 30%, the assembling property when inserting the collet 31 into the arm shaft 11 deteriorates, as shown in FIG. .. Further, as a result of various experiments, it was found that when the crushing rate exceeds 41% in the configuration as shown in FIG. 1, the O-ring is compressed and the O-ring is damaged as shown in FIG. Therefore, based on the findings shown in FIG. 9, the present inventors have shown in FIG. 1 in order to minimize the compression set of the O-ring and to ensure the assembling property when the collet 31 is inserted into the arm shaft 11. the compression rate epsilon ₁ and compression rate epsilon ₂ of the second O-ring 23 of the first O-ring 21 in the structure as was selected respectively from 17 to 19%.

In general rod seal and piston seal designs, _{it is recommended that the insertion angle θ i} be selected in the range of 15 to 30 °. In the vacuum suction arm according to the embodiment, the minimum diameter of the tip of the collet 31 is set so that the collet 31 can be easily inserted into the first O-ring 21 and the second O-ring 23 fixed to the arm shaft 15. It is made smaller than the minimum diameter d _{0 of} the first outer peripheral surface groove OG _{22 and the like.} As described above, since the crushing rate ε ₁ = ε ₂ of the chamfer is selected to be 17 to 19%, the insertion angle θ _i is 24.5 to 25.5 ° in the vacuum suction arm according to the embodiment. By selecting the range of, the insertion inclined surface S ₁ which is a chamfered surface can play a role of a good shoehorn (guide surface).

Since the purpose of the vacuum suction arm according to the embodiment is to obtain insertion / extraction durability and ease of insertion / removal for inserting the collet 31 into the arm shaft 11, the holding length L which is the length _{of the holding surface S 2 of the collet 31 h1} is selected to be 1/3 to 1/4 of _{the wire diameter D 1} of the first O-ring 21 and the wire _{diameter D 2} of the second O-ring 23, respectively. _{For example, if the wire diameter D 1} of the first O-ring 21 is 1 mm, the holding length L _{h 1} can be selected to be 02.25 mm. When the holding length L _h1 is larger than 1/3 of the O-ring wire diameters D ₁ and D ₂ , it becomes difficult to insert and remove the collet 31 into the arm shaft 11, and the O-ring insertion / removal durability deteriorates. On the other hand, if the holding length L _h1 is smaller than 1/4 of the O-ring wire diameters D ₁ and D ₂ , the desired holding force when the collet 31 is inserted into the arm shaft 11 cannot be realized.

FIG. 2 is shown in order to achieve the insertion / removal durability of the O-ring, the ease of insertion / removal of the collet 31 with respect to the arm shaft 11, and the desired holding force when the collet 31 is inserted into the arm shaft 11. It is preferable to select the holding angle θ _h formed by the holding inclined surface S ₃ and the inner wall surface S ₄ of the through hole 33 in the range of 42 to 48 °, particularly in the range of 44 to 46 °. If the holding angle θ _h is smaller than 42 °, the desired holding force when the collet 31 is inserted into the arm shaft 11 cannot be achieved. On the other hand, when the holding angle θ _h is larger than 48 °, it becomes difficult to insert and remove the collet 31 into the arm shaft 11, and the insertion / removal durability of the O-ring deteriorates.

As shown in FIGS. 1A and 1B, in the vacuum suction arm according to the embodiment, a nozzle tip having a conical outer diameter and a hollow tip is provided on the lower side of the collet 31. Inside the nozzle tip, a through hole 33 extending upward from the tip and penetrating the collet 31 is provided so as to be continuous with the vacuum suction hole 13. The lower part of the arm shaft 11 functions as a "collet insertion hole". When the upper insertion portion of the collet 31 is inserted into the lower part of the arm shaft 11, the first O-ring 21 and the second O-ring 23 are inserted into the first outer peripheral surface groove OG ₁₂ and the second outer peripheral surface groove OG ₁₁ , respectively. It is retained and the desired retaining force is achieved.

As shown in FIGS. 1A and 1B, a vacuum piping joint (adapter) 51 continuous with the vacuum suction hole 13 is fixed to the upper end of the arm shaft 11. When the insertion portion of the upper part of the collet 31 is inserted into the arm shaft 11, air is sucked by the vacuum pump through the adapter 51, so that the vacuum suction hole 13 and the through hole 33 become negative pressure, and the tip of the collet 31 It is a mechanism in which electronic components are attracted to the part. When the vacuum suction hole 13 and the through hole 33 are made positive pressure while the electronic component is adsorbed, the adsorbed electronic component is detached from the tip portion of the collet 31.

The depths of the first inner peripheral groove 15 and the second inner peripheral groove 17 provided on the arm shaft 11 shown in FIG. 1 (c) are t ₁₂ and t _{11 as shown in FIG. 4, respectively.} The widths of the grooves are W ₁₂ and W ₁₁ , respectively. As shown in FIG. 1 (c), the first O-ring 21 and the second O-ring 23 are fitted to the first inner peripheral surface groove 15 and the second inner peripheral surface groove 17, respectively. In order for the first O-ring 21 to properly function, the groove depth t ₁₂ and width W ₁₂ of the first inner peripheral groove 15 are determined by the crushing rate ε ₁ = 17 to 19 of the first O-ring 21. The dimensions are designed so that _{the crushing allowance δ 1} of the first O-ring 21 and the appropriate relief allowance for the crushing allowance δ _{1 are secured in consideration of% and the insertion pressure.} Similarly, in order for the second O-ring 23 to properly function, the groove depth t ₁₁ and width W _{11 of the second inner peripheral groove 17 are determined by the crushing rate ε 2} = of the second O-ring 23. It is designed to have dimensions that ensure an appropriate relief allowance for the crushing allowance δ ₂ of the second O-ring 23 and the crushing allowance δ _{2 in consideration of 17 to 19% and the insertion pressure.} Further, it is measured at the bottom _{of the first outer peripheral groove OG 12 on} the outer peripheral surface of the collet 31 facing the first inner peripheral groove 15 and _{the second outer peripheral groove OG 11} facing the second inner peripheral groove 17. The minimum diameter d _{0 of the} collet 31 is selected. The depth of the bottom of the grooves of the first inner peripheral groove 15 and the second inner peripheral groove 17 provided on the arm shaft 11 is such that the outer diameter tension ratio of the first O-ring 21 and the second O-ring 23 is 0. Selected to be ~ 3%.

As described above, in the vacuum suction arm according to the embodiment, when the collet 31 is inserted into the arm shaft 11, the insertion operation of the collet 31 is not hindered, and the first inner peripheral groove 15 and the second inner circumference are not hindered. _{The groove depths t 12} and t ₁₁ and the widths W ₁₂ and W ₁₁ are adjusted so that the first O-ring 21 and the second O-ring 23 do not come off from the surface groove 17.

The widths W ₁₂ and W ₁₁ of the first O-ring 21 and the second O-ring 23 are the first O-ring 21 if the durometer hardness of the first O-ring 21 and the second O-ring 23 is about 70 to 90 degrees. _{And the filling rates n 1} and n _{2 of} the second O-ring 23 are set to be 70 to 80%. The crushing rate n ₁ of the first O-ring 21 is determined by using _{the crushing allowance δ 1} of the first O-ring 21 and the wire diameter D _1.

n ₁ = πD ₁ ² / (4W ₁₂ (D _{1 −} δ ₁ )) × 100 …… (3)

It is expressed as. Similarly, the crushing rate n ₂ of the second O-ring 23 is determined by using _{the crushing allowance δ 2} of the second O-ring 23 and the wire diameter D _2.

n ₂ = πD ₂ ² / (4W ₁₁ (D _2- δ ₂ )) × 100 …… (4)

Will be.

In FIG. 1 (c), the minimum diameter _{d 0} of the collet 31 is the inner diameter clad ratio of the first O-ring 21 and the second O-ring 23 is chosen to be 1-5%, of the minimum diameter _{d 0} The value is the inner diameter considering the crushing allowances δ ₁ and δ ₂ when the first O-ring 21 and the second O-ring 23 are fixed, or the crushing allowance δ _{1 when the first O-ring 21 and the second O-ring 23 are fixed.} , Δ ₂ is added to the inner diameter with a constant play diameter Δ.

In the vacuum suction arm according to the reference example shown in FIGS. 3 and 5, d ₁ is guided as the diameter of the collet 31 in the wide groove 35 without the first outer peripheral groove OG ₁₂ and the second outer peripheral groove OG _11. The outer diameter d ₃ = d ₁ . If the guide portion outer diameter d ₃ is equal to the diameter of the surface of the wide groove 35 without the first outer peripheral surface groove OG ₁₂ and the second outer peripheral surface groove OG ₁₁ , the insertion becomes easier, but the collet 31 is attached to the arm shaft 11. It is not preferable because the desired holding force at the time of inserting the is not realized.

Therefore, as in the vacuum suction arm according to the embodiment shown in FIG. 1 (c), the _{holding surface S 2} is set as the upper surface of the holding convex portion in the centrifugal direction from the central axis _{with the guide portion outer diameter d 3} > d _1. It is preferable to have a structure in which the collet 31's insertion portion is inserted into the arm shaft 11 to strengthen the fixing force in the inserted state. The positions of the first outer peripheral groove OG ₁₂ and the second outer peripheral groove OG _{11 in} the tubular axis direction are such that the first and second O-rings of the arm shaft are inserted into the arm shaft when the collet 31 is inserted into the arm shaft. Any position may be used as long as it is held and fixed. The wide groove 35, the first outer peripheral groove OG ₁₂ , and the second outer peripheral groove OG ₁₁ are engraved on the outer peripheral surface of the insertion portion of the collet 31, so that the first O-ring 21 and the second O-ring 21 along the tubular axis direction are engraved. The relative position of the O-ring 23 is accurately determined. In FIG. 5, the first outer peripheral surface groove OG ₁₂ and the second outer peripheral surface groove OG ₁₁ are preferably V-shaped in cross section having a holding angle θ _h in the range of 42 to 48 °, and the first outer peripheral surface groove OG _{The cross-sectional shape of the 12} and the second outer peripheral groove OG ₁₁ has a holding angle θ _hp of 90 _{formed by the holding inclined surface S 3p and the inner wall surface S 4} of the through hole 33 as in the comparative examples shown in FIGS. 7 and 10. In the case of a U-shape or a U-shape with °, it becomes difficult to easily insert and remove the collet 31 into the arm shaft 11, and the insertion and removal durability of the O-ring deteriorates, which is not preferable. In the normal design of the collet 31 according to the comparative example shown in FIG. 10, the O-ring crushing rates ε ₁ and ε ₂ are set to be smaller than 17 to 19%. Therefore, in the collet 31 according to the comparative example, the inner diameter of the O-ring can be made larger than that shown in FIG. 2, and the insertion angle θ _{ip formed by the insertion inclined surface S 1p} of the collet 31 and the inner wall surface S _{4 of the through hole 33.} Is generally set to about 15 °, and the insertion angle θ _i shown in FIG. 2 is generally made smaller than that.

(Collet insertion operation)
The operation of inserting the collet 31 into the arm shaft 11 will be described with reference to FIGS. 1 (c), 2 and 4 and the like. _{When inserting the insertion portion of the collet 31 into the arm shaft 11, first, the insertion inclined surface S 1 at} the tip of the collet 31 is inserted into the second O-ring 23 fitted in the second inner peripheral surface groove 17 of the arm shaft 11. Contact, and then the _{holding surface S 2,} which is the upper surface of the holding convex portion continuous with _{the insertion inclined surface S 1} , comes into contact. _{The insertion portion of the collet 31 is inserted while the holding surface S 2} which is the upper surface of the holding convex portion of the guide portion outer diameter d ₃ continues to be pressed toward the central axis of the arm shaft 11 from the second O-ring 23. When the holding surface S ₂ of the collet 31 is released from the contact with the second O-ring 23, the second O-ring 23 comes into contact with the wide groove 35 of the collet 31.

_{Next, when the holding surface S 2} which is the upper surface of the holding convex portion of the collet 31 comes into contact with the first O-ring 21 fitted in the first inner peripheral surface groove 15, it may come into contact with the second O-ring 23. _{Similarly, the holding surface S 2} receives the pressure from the first O-ring 21 toward the central axis of the arm shaft 11. When the insertion operation proceeds and the contact between the first O-ring 21 and the holding surface S _{2 of the guide portion outer diameter d 3} is released, the first O-ring 21 comes into contact with _{the holding inclined surface S 3 of the wide groove 35.} become. At the position where the stopper 37 provided on the collet 31 is held by the stopper receiving portion 19 provided on the arm shaft 11, subsequent insertion does not proceed. In this position, the first O-ring 21 held on the first outer peripheral surface groove OG _12, the first outer peripheral surface groove OG ₁₂ to undergo pressing toward the central axis of the arm shaft 11 from the first O-ring 21 become. At this time, the second O-ring 23 held in the second outer peripheral surface grooves OG _11, second outer peripheral surface grooves OG ₁₁ receives a pressing toward the central axis of the arm shaft 11 from the second O-ring 23.

Compression rate of the first O-ring 21 epsilon ₁ and compression rate epsilon ₂ was different from that of the second O-ring 23, the depth t ₁₂ of the grooves of the first inner circumferential surface grooves 15 shown in FIG. 4, within the second circumferential The groove depth t ₁₁ of the surface groove 17 is set to

t ₁₂ <t ₁₁ …… (5)

Therefore, the insertion pressure of the insertion portion of the collet 31 into the arm shaft 11 can be reduced. Alternatively, with respect to the width W ₁₁ of the grooves of the width W ₁₂ of the grooves of the first inner circumferential surface grooves 15 shown in FIG. 4 the second inner peripheral surface groove 17,

W ₁₂ <W ₁₁ …… (6)

Therefore, the insertion pressure of the insertion portion of the collet 31 into the arm shaft 11 can be reduced.

It is also possible to make the filling factor n _{1 of the first O-ring 21 larger than the filling factor n 2} of the second O-ring 23 to reduce the insertion pressure of the insertion portion of the collet 31 into the arm shaft 11. That is:

n ₁ > n ₂ …… (7)

_{The crushing allowance δ 1} and the wire diameter D _{1 of the first O-ring 21 and the crushing allowance δ 2} and the wire diameter D _{2 of} the second O-ring 23 described in the equations (3) and (4) are set so as to be. You may adjust it. In any case, the insertion operation of the insertion portion of the collet 31 into the arm shaft 11 can be performed with one touch as described above. The collet 31 can be removed from the arm shaft 11 with a single touch by the reverse mechanism of the insertion operation.

As described above, the diameter d ₃ > d _{1 of the upper part of the collet 31 is set, and the holding convex portion having the holding length L h1 in} the centrifugal direction from the central axis is formed from 1/3 of the O-ring wire diameters D ₁ and D _2. Since it is selected to exist in 1/4, the insertion pressure when the insertion portion of the collet 31 is inserted into the arm shaft 11 becomes an appropriate magnitude for insertion. Then, as shown in FIG. 1 (c) _{, the holding surface S 2} which is the upper surface of the holding convex portion _{having the guide portion outer diameter d 3} provided in the insertion portion of the collet 31 is after the contact with the second O-ring 23. It functions as a guide to realize a smooth insertion operation. The holding surface S ₂ and the holding surface wide groove 35 of diameter d ₁ which is defined a stepped shape in the holding surface S ₂ that is continuous with S ₂ includes a holding surface S ₂ is the second O-ring 23 of the holding length L _h1 A smooth insertion operation after the contact of the collet 31 is realized. If there is no wide groove 35 having a diameter d ₁ , in the insertion operation of the collet 31, the outer peripheral surface having the guide portion outer diameter d ₃ is the second O-ring after the holding of the first outer peripheral groove OG 12 and the second O-ring 23. This is because the contact with the 23 is continued, and a larger pressure is received from the second O-ring 23 as compared with the case where the _{diameter is d 1, and the insertion operation does not proceed smoothly.} The wide groove 35 is important for realizing a smooth removal operation of the collet 31 for the same reason.

(Comparison example)
A vacuum suction arm according to a comparative example of the embodiment of the present invention will be described with reference to FIGS. 6 and 7. The depths of the first inner peripheral groove 15 and the second inner peripheral groove 17 of the arm shaft 11 in FIG. 6 are t ₂₂ and t ₂₁ , respectively, which are shallower than the arm shaft 11 in FIG.

t ₁₂ > t ₂₂ …… (8)
t ₁₁ > t ₂₁ …… (9)

When the first and second O-rings having the same nominal diameter are used, it corresponds to a structure in which the diameter of the vacuum suction hole 13 is larger than that in the case of FIG. In the structure shown in FIG. 6, the inner diameter side of the first auring 21 and the second auring 23 protrudes more in the central axis direction of the vacuum suction hole 13 than in the structure shown in FIG. ..

The structure of the collet 31 of the vacuum suction arm according to the comparative example shown in FIG. 7 has a _{U-shaped groove having a holding angle θ hp} of 90 °, and further, the implementation illustrated in FIG. 1 (c). It does not have a wide groove 35 like the collet 31 of the vacuum suction arm according to the embodiment. In FIG. 7, d ₀ is the minimum diameter of the collet 31 at the bottom surface of the first outer peripheral groove OG ₂₂ and the second outer peripheral groove OG ₂₁ , and is crushed when the first O-ring 21 and the second O-ring 23 are fixed. Since it is a value corresponding to the inner diameter considering the digits δ _{1 and δ 2} , it is the same as the _{minimum diameter d 0 shown in FIG.} The insertion portion outer diameter d ₂ in FIG. 7 is the diameter on the outer peripheral surface of the insertion portion of the collet 31 without the first inner diameter side ring groove OG ₂₂ and the second inner diameter side ring groove OG _21. Insertion outer diameter) _{larger than d 1,} but smaller than the upper diameter d _{3 of the collet 31:}

d ₃ > d ₂ > d ₁ …… (10)

The depth t of the first inner diameter side ring groove OG ₂₂ and the second inner diameter side ring groove OG _{21 groove is:}

t _inner = (d _2- d ₀ ) / 2 …… (11)

The value of t _{inner is the depth t 22} , t _{21 of} the first inner peripheral groove 15 or the second inner peripheral groove 17 provided on the arm shaft 11 side, and the first O-ring 21 or the second. It is determined in consideration _{of the crushing allowances δ 1} and δ ₂ when the O-ring 23 is fixed. The outer peripheral surface of the insertion portion having the insertion portion outer diameter d ₂ is the portion having the largest area in contact with the first O-ring 21 and the second O-ring 23 when the insertion portion of the collet 31 is inserted. In Figure 7, the holding projection of the guide outer diameter d ₃ in FIG. 2 is absent. When the same first O-ring 21 and second O-ring 23 as shown in FIG. 2 are used, in FIG. 7, the outer peripheral surface having the largest area in contact with the first O-ring 21 and the second O-ring 23 in FIG. that for the insertion the outer diameter d ₁ greater insertion outer diameter d _2, the first O-ring 21 and the second O-ring 23 is easily disengaged more from the first inner circumferential surface grooves 15 and the second inner peripheral surface groove 17 Problems arise. Moreover, since there is no portion corresponding to the holding projection of the guide outer diameter d ₃ in FIG. 2, even if a problem that it becomes easier to escape though to insert the collet 31 results.

The materials of the first O-ring 21 and the second O-ring 23 in FIGS. 1 (b) and 1 (c) are fluororubbers that partially or wholly use fluororesin as raw materials, according to the JIS standard (JISK6253). It is particularly preferable in that the indentation hardness (hardness) of the specified type A durometer is moderately hard at 70 to 90 degrees, the workability is high, and the friction coefficient of the surface is small. Other materials used for O-ring, such as natural rubber or synthetic rubber such as polybutadiene-based, nitrile-based, and chloroprene-based rubber, may be used, but first O-ring 21 and second O-ring 23 made of materials other than fluorine-based rubber are used. In this case, the setting ranges such as _{the insertion angle θ i} , the holding angle θ _h, and the holding length L _{h 1 are narrowed.} Further, when a material other than the fluorine-based rubber is used, it is generally not preferable because the fixing force in the state where the collet 31 is inserted into the arm shaft 11 tends not to be sufficiently obtained. If the collet 31 is inserted into the arm shaft 11 and the fixing force is not reduced, the first O-ring 21 and the second O-ring 23 are provided if they have strength and rubber elasticity that can withstand use and processing. Any material can be used.

The materials of the arm shaft 11 and the collet 31 in FIGS. 1 (a), 1 (b), and (c) are mainly metals, but if they have strength enough to withstand use and processing, for example, glass fiber or carbon. Fiber reinforced plastic (FRP) to which fibers and the like are added, or a composite material having a metal material inside and injection-molding plastic around it may be used.

When the collet 31 is held on the arm shaft 11 by using an O-ring, increasing the holding force and the ease of inserting and removing the collet 31 are in a trade-off relationship. Further, the holding force for holding the collet 31 on the arm shaft 11 and the O-ring insertion / removal durability are in a trade-off relationship. As shown in FIGS. 1, 2 and 4, the vacuum suction arm according to the embodiment can be inserted and removed from the collet 31 with a low insertion pressure, so that the collet 31 can be inserted and removed from the arm shaft 11 with one touch. The holding force for holding the collet 31 on the arm shaft 11 can be increased to a desired value. In addition, the collet 31, which is a constituent member of the vacuum suction arm and is a replacement member, only needs to be machined on the outer peripheral surface, has almost no effect on the through hole 13, and has high O-ring insertion / removal durability. Therefore, the collet 31 can be easily processed by using a lathe or the like, and therefore, an inexpensive and highly durable vacuum suction arm can be realized.

(Other embodiments)
Although the present invention has been described in accordance with the above embodiments, the statements and drawings that form part of this disclosure should not be understood as limiting the invention. Various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art from this disclosure.

It is also possible to appropriately combine some of the individual technical ideas described in the above embodiments with each other. As described above, it goes without saying that the present invention includes various embodiments not described here. Therefore, the technical scope of the present invention is defined only by the matters specifying the invention relating to the claims, which can be interpreted as appropriate from the above description.

11 ... Arm shaft 13 ... Vacuum suction hole 13
15 ... 1st inner peripheral groove 17 ... 2nd inner peripheral groove 19 ... Stopper receiving portion 21 ... 1st O-ring (O-ring)
23 ... 2nd O-ring (O-ring)
31 ... Collet 33 ... Through hole 35 ... Wide groove 37 ... Stopper 51 ... Vacuum piping joint (adapter)
OG ₁₁ ... Second outer peripheral groove OG ₁₂ ... First outer peripheral groove OG ₂₁ ... Second inner diameter side ring groove OG ₂₂ ... First inner diameter side ring groove

Claims (2)

An arm shaft having a first tubular shape surrounding the vacuum suction hole and having first and second inner peripheral grooves provided parallel to each other on the first tubular inner peripheral surface.
A part of each is fitted into the first and second inner peripheral surface grooves, and a part of each remaining portion is projected from the inner peripheral surface toward the central axis of the vacuum suction hole. 2 O-rings and
The tip has a holding convex portion whose outer peripheral surface is defined by a holding surface having an outer diameter smaller than the diameter of the inner peripheral surface, and is continuous with the holding convex portion and has a diameter smaller than that of the holding convex portion. A collet having a concavo-convex second tubular shape having a wide groove and having first and second outer peripheral groove grooves provided parallel to each other at the bottom of the wide groove.
The vacuum suction arm is characterized in that, when the upper portion is inserted into the lower portion of the arm shaft, the first and second O-rings are held in the first and second outer peripheral surface grooves, respectively. The first tubular shape surrounding the vacuum suction hole, and the first and second inner peripheral surface grooves are inserted into an arm shaft provided on the first tubular inner peripheral surface so as to be parallel to each other. The tip has a holding convex portion whose outer peripheral surface is defined by a holding surface having an outer diameter smaller than the diameter of the inner peripheral surface, is continuous with the holding convex portion, and has a wider diameter than the holding convex portion. A collet having a grooved, concave-convex shape and a second tubular shape.
The bottom of the wide groove is provided with first and second outer peripheral grooves provided parallel to each other.
A part of each of the first and second O-rings is fitted into the first and second inner peripheral surface grooves, and a part of each remaining portion is directed from the inner peripheral surface toward the central axis of the vacuum suction hole. When the upper portion is inserted into the lower portion of the arm shaft in the protruding state, the first and second O-rings are held in the first and second outer peripheral surface grooves, respectively. Collet.

Images