CN111113127A

CN111113127A - Conveying device

Info

Publication number: CN111113127A
Application number: CN201910979037.6A
Authority: CN
Inventors: 渡边正辉
Original assignee: Brother Industries Ltd
Current assignee: Brother Industries Ltd
Priority date: 2018-10-30
Filing date: 2019-10-15
Publication date: 2020-05-08
Anticipated expiration: 2039-10-15
Also published as: CN111113127B; JP2020069562A; JP7067419B2

Abstract

The invention provides a conveying device capable of preventing cooling liquid from falling to pollute an installation space when a workpiece is taken out or put in. The conveying device comprises: a conveyor having an arm capable of gripping a workpiece, the arm being movable between an inside and an outside of the machine tool; and a housing body having: a holding plate which holds a workpiece and has a 1 st opening; a movable part which supports the holding plate and is slidable via the guide part; and a 1 st receiving portion that receives the coolant below the 1 st opening portion.

Description

Conveying device

Technical Field

The present invention relates to a conveyor device having a conveyor having an arm capable of gripping a workpiece, the arm being movable between the inside and the outside of a machine tool.

Background

A machining apparatus is known in which a conveyor for conveying a workpiece is disposed adjacent to a side wall of a machine tool. In japanese patent laid-open publication No. 2017-177287, an arm of a conveyor moves between the inside and the outside of a machine tool through a window formed in a wall surface of the machine tool, and exchanges workpieces. In this processing apparatus, a rack for storing a plurality of workpieces may be disposed beside the conveyor. The arm of the conveyor holds the workpiece from the rack, takes the workpiece out, and feeds the workpiece into the machine tool. The processing device is provided with a safety fence surrounding the conveyor and the material rack. The safety fence is provided with a door for an operator to take out and put in the workpiece relative to the material rack.

In this processing apparatus, when the operator exchanges the workpiece each time, the operator needs to open the door to enter the inside, and take out and put in the workpiece with respect to the rack, which makes the operation complicated.

When the arm takes out and puts in the workpiece between the machine tool and the work rack, there is a problem that the coolant adhering to the workpiece falls down to contaminate the floor when taking out and putting in the workpiece with respect to the work rack.

Disclosure of Invention

The invention aims to provide a conveying device which can prevent cooling liquid from falling and polluting when a workpiece is taken out and put in.

The conveying device according to claim 1 comprises: a conveyor having an arm capable of gripping a workpiece, the arm being movable between an inside and an outside of the machine tool; and a housing body having: a holding plate which holds the workpiece and has a 1 st opening; a movable portion that supports the holding plate and is slidable via a guide portion; and a 1 st receiving portion that receives the coolant below the 1 st opening portion.

Since the cooling liquid dropped from the workpiece is received by the 1 st receiving portion below the movable portion and the 1 st opening, contamination of the installation space can be suppressed. The coolant can be recovered.

The conveying device according to claim 2 includes: a housing provided with a 2 nd opening through which the arm can enter and exit; a substrate provided on the housing; and an attachment plate attached to the substrate, the attachment plate being provided with a fixing portion extending in a front-back direction of the case.

In the transport apparatus according to claim 3, the mounting plate and the substrate have a 3 rd opening and a 4 th opening, respectively, and the transport apparatus has a 2 nd receiving portion that receives the cooling liquid below the 4 th opening.

The 2 nd receiving portion receives the coolant falling from the 3 rd opening portion and the 4 th opening portion, and therefore contamination of the installation space can be suppressed more favorably.

The conveyor device according to claim 4 has a 3 rd receiving portion that receives the coolant on the lower side of the conveyor.

Since the cooling liquid dropped when the workpiece moves is received by the 3 rd receiving part between the holding plate and the machine tool, which is the lower side of the conveyor, contamination of the installation space can be more favorably suppressed

In the transport device according to claim 5, the 1 st receiving unit, the 2 nd receiving unit, or the 3 rd receiving unit has an inclined surface, and a liquid collecting unit having an opening is provided at a lower end of the inclined surface.

The coolant can be collected in the liquid collecting part well, and the coolant can be easily collected.

Drawings

Fig. 1 is a perspective view of the processing apparatus as viewed from the front.

Fig. 2 is a front view of the processing apparatus.

Fig. 3 is a right side view of the processing apparatus.

Fig. 4 is a plan view of the processing apparatus.

Fig. 5 is a perspective view of the processing apparatus with the 2 nd housing and the storage body of the conveying unit removed.

Fig. 6 is a perspective view of the conveying device.

Fig. 7 is a plan view of the conveying device.

Fig. 8 is a sectional view VIII-VIII of fig. 7.

Fig. 9 is a cross-sectional view IX-IX of fig. 7.

Fig. 10 is a perspective view of the pull-out portion.

Fig. 11 is a perspective view of the drawer in a state where the work and the tray are removed.

Fig. 12 is a cross-sectional view XII-XII of fig. 10.

Fig. 13 is a partially enlarged perspective view of the front plate.

Detailed Description

In the following description, the top, bottom, front, rear, left, and right of the drawings are used. As shown in fig. 1 and 2, the machining apparatus 10 includes a machine tool 1 and a conveying device 5, and the conveying device 5 includes a conveying unit 3 and a storage body 4.

The machine tool 1 includes a base 12 and a column 13 provided on the base 12. The column 13 supports the spindle head 17 so that the spindle head 17 can move up and down. The spindle head 17 supports the spindle 14 so that the spindle 14 can rotate, and the spindle 14 has a vertical direction as a rotation axis direction. A spindle motor 15 is provided at the upper end of the spindle head 17. The spindle 14 is rotated by a spindle motor 15.

The column 13 supports a tool magazine 16. The tool magazine 16 is disposed on the front side of the spindle head 17. A plurality of tools are held around the magazine 16. The tool magazine 16 rotates, and the tool is attached to and detached from the spindle 14 by the vertical movement of the spindle head 17. A table 20 is disposed below the main shaft 14 and is movable in the left-right direction and the front-rear direction. The jig 24 (see fig. 4) is provided on the table 20. The jig 24 holds and releases the workpiece 6.

The cover 11 covers the upper side, front side, rear side, right side, and left side of the machine tool 1. The door 18 is provided on the front surface of the hood 11. An operation unit 21 for receiving an operation by an operator and a display unit 22 for displaying an image are provided on the right side of the door 18. The control device 19 is provided on the rear side of the cover 11. The liquid sump 8 is disposed below the control device 19, and the liquid sump 8 stores a coolant used when the workpiece 6 is processed, which will be described later. The coolant is used to cool frictional heat during processing.

As shown in fig. 5, an opening/closing door 23 is provided on the right surface of the cover 11, i.e., the right wall surface of the machine tool 1.

The right side of the opening/closing door 23 is provided with the conveying section 3 of the conveying device 5. The conveying unit 3 includes a conveyor 30, a guide 33, and a 2 nd casing 35. The conveyor 30 has a support table 31 and an arm 32. The support base 31 is in the shape of a column extending vertically. The arm 32 is provided at the upper end of the support table 31, and the arm 32 moves up and down and left and right. The grip 32a is provided at the distal end of the arm 32.

A guide portion 33 for guiding the support table 31 is provided between the lower portion of the support table 31 and the machine tool 1. The guide portion 33 includes a guide table (not shown), a front plate portion 33a, and a rear plate portion 33 b. The front plate portion 33a and the rear plate portion 33b are opposed to each other in the front-rear direction of the guide table. The guide table is connected to the base 12 via a connection portion 2 (see fig. 2). The guide table is provided with a rail (not shown). The rail extends forward and backward, and the lower portion of the support base 31 is slidably connected to the rail. The support base 31 is connected to a ball screw mechanism (not shown). The ball screw mechanism is disposed on the guide table. The support table 31 moves back and forth along the rails by the driving of the ball screw mechanism.

Two bellows-shaped covers 34 are provided on the right side between the front plate portion 33a and the rear plate portion 33 b. One cover 34 connects the lower front side of the support base 31 to the front plate portion 33a, and the other cover 34 connects the lower rear side of the support base 31 to the rear plate portion 33 b. The cover 34 covers the rail and the ball screw mechanism from the right side. The cylinder 31a provided at the upper end of the support table 31 is movable in the left-right direction. The opening/closing door 23 is provided with a recess 23a engageable with the tip end of the cylinder 31 a. The cylinder 31a protrudes leftward and engages with the recess 23a, and the opening/closing door 23 is opened and closed by moving the support base 31 in the front-rear direction by the ball screw mechanism. The cylinder 31a is retracted rightward, and the engagement with the recess 23a is released, so that the support base 31 can move in the front-rear direction without operating the opening/closing door 23. The control device 19 controls the movement of the cylinder 31a in the left-right direction, and the cylinder 31a engages with the recess 23a to open the opening/closing door 23. The control device 19 controls the movement of the arm 32, and the arm 32 moves between the inside and the outside of the machine tool 1. The inside and outside of the machine tool 1 refer to the inside and outside of the cover 11. The control device 19 drives the ball screw mechanism, and the arm 32 moves forward and backward. The hood 34 extends and contracts in accordance with the forward and backward movement of the arm 32, and continuously covers the rail and the ball screw mechanism.

The 3 rd receiving portion 7 for receiving the coolant is disposed below the guide portion 33. The 3 rd receiving portion 7 has a tray 71, a moving leg 72, a wheel 73, and an adjusting portion 74. The tray 71 has a rectangular plate shape extending in the front-rear direction, and has a wall protruding upward at the peripheral edge. The moving legs 72 are provided at four corners of the tray 71. Wheels 73 and an adjusting portion 74 are provided at the lower end portions of the moving legs 72. The tray 71 is moved by the wheels 73, and after the tray 71 is placed at a predetermined position, the height of the tray 71 can be adjusted by the adjusting portion 74. An opening (liquid collecting portion) 75 is provided at the left end of the rear surface of the tray 71, and the opening 75 is connected to a pipe 76. The pipe 76 is connected to the liquid storage tank 8.

When the arm 32 moves while holding the workpiece 6, the coolant adhering to the workpiece 6 falls down to the tray 71. By the adjustment of the 4 adjusting portions 74, the tray 71 is inclined in a manner of being high in the front and low in the rear, and is inclined in a manner of being high in the right and low in the left. Therefore, the coolant accumulated in the tray 71 is collected toward the opening 75 and moves from the pipe 76 to the liquid storage tank 8. That is, the opening 75 is disposed at the lower end of the inclined surface of the tray 71.

As shown in fig. 6, the 2 nd housing 35 has openings on the upper and lower surfaces, and the 2 nd housing 35 has an opening 35a on the left side surface on the machine tool 1 side. The right side surface of the 2 nd case 35 is partially opened and communicates with an opening 41a on the left side surface of the 1 st case 41 of the housing 4 described later.

The length in the up-down direction of the left side surface of the 2 nd case 35 is shorter than the length in the up-down direction of the right side surface. The position of the lower surface is defined so that the 3 rd receiving portion 7 can be housed below the lower surface of the 2 nd case 35, and the 3 rd receiving portion 7 is housed below the lower surface. The 3 rd receiving unit 7 has wheels 73 and can be pulled out, and therefore cleaning is easy.

Each wall of the 2 nd case 35 includes a plurality of cover plates. The cover plate 35c, the cover plate 35d, and the cover plate 35e having wall surfaces on the front side of the right side surface, and the cover plate 35b on the front side are detachably fixed by screws. The cover plate may also be door-shaped.

The two connecting portions 37 are provided up and down on the left portion of the rear side of the 2 nd housing 35, respectively. The connecting portion 37 extends in the front-rear direction, and a front end surface of the connecting portion 37 is connected to a rear side portion of a peripheral edge of the opening/closing door 23 of the machine tool 1 by screwing. An operation panel 36 for operating the conveyor 30 is provided in the center of the front surface of the 2 nd housing 35.

The housing 4 has a 1 st case 41. The 1 st case 41 has an opening on the upper surface thereof, and the 1 st case 41 has an opening 41a on the left side surface of the 2 nd case 35. The front side surface of the 1 st case 41 is constituted by a cover plate 41b, a cover plate 41c, and a cover plate 41d in this order from above, and the right side surface is constituted by a cover plate 41e, a cover plate 41f, and a cover plate 41g in this order from above. The rear side of the 1 st case 41 is constituted by a back plate 41 h. The cover plates 41b to 41f are detachably fixed by screws. The cover plate may also be door-shaped. The cover plate 41c has an opening, and the pull-out portion 42 is pulled out from the opening.

As shown in fig. 7, the drawer 42 includes a base plate 43, a mounting plate 44, a 1 st fixing portion 45, a movable portion 50, a stage 54, and a tray 55.

The base plate 43 is erected between the side surfaces at the lower portion of the cover plate 41 c. The base plate 43 has a pin 43a at the center of the rear end edge portion and a plurality of female screws 43b in the front-rear direction at the left and right end edge portions. As shown in fig. 9, the 2 nd receiving portion 67 for receiving the coolant is disposed below the substrate 43. The substrate 43 has an opening 43c at the center.

As shown in fig. 7, the mounting plate 44 is slightly smaller than the base plate 43, and has a through hole 44d through which the pin 43a passes in the center portion of the rear end edge portion, and a plurality of long holes 44c corresponding to female screws and extending in the left-right direction in the left-right end edge portions. After the mounting plate 44 is positioned by inserting the pin 43a through the through hole 44d, the mounting plate 44 is mounted on the base plate 43 by fastening the plurality of screws 44b to the female screw.

The mounting plate 44 can be fixed to the base plate 43 at an angle by the elongated hole 44 c. That is, the mounting plate 44 is attached to the base plate 43 so as to be rotatable clockwise or counterclockwise about the pin 43a as a fulcrum by the pin 43a, the female screw 43b, the through hole 44d, the long hole 44c, and the screw 44 b.

The pin 43a and the through hole 44d are not limited to those provided in the center portion of the rear end edge portions of the base plate 43 and the mounting plate 44, and may be provided in the corner portions and the center portion of the base plate 43 and the mounting plate 44.

The mounting plate 44 has an opening 44a in the center. As shown in fig. 7 and 8, the 1 st fixing portion 45 and the 2 nd fixing portion 46 extending in the front-rear direction are fixed to the left and right end edges of the mounting plate 44. A 2 nd fixing portion 46 extending in the front-rear direction and having a height lower than that of the 1 st fixing portion 45 is provided inside the 1 st fixing portion 45. A 3 rd fixing portion 48 having a height higher than that of the 2 nd fixing portion 46 and a length in the front-rear direction shorter than that of the 2 nd fixing portion 46 is provided inside the 2 nd fixing portion 46 on the right side. As shown in fig. 7 and 12, a plurality of rollers 47 are attached to the outer side surface of the 2 nd fixing portion 46 in the front-rear direction with the left-right direction as the rotation axis direction. A rack 49 extending along the right side surface and having a tooth portion at the upper portion is provided at the upper portion of the right side surface of the 3 rd fixing portion 48.

The movable portion 50 is located above the roller 47 and has a plate shape extending in the front-rear direction. The 1 st guide portion 51 is interposed between the movable portion 50 and the 1 st fixing portion 45. The 1 st guide portion 51 guides the movable portion 50, and the movable portion 50 slides with respect to the 1 st fixing portion 45. A pinion gear 52 whose rotation axis direction is the left-right direction is provided on the inner side surface of the movable portion 50. The pinion 52 meshes with the rack 49.

As shown in fig. 7, a plurality of stoppers 61 that abut against the rear end surface of the movable portion 50 are provided at the rear end portion of the attachment plate 44. The 1 st fixing portion 45 is provided with a sensor 62 for detecting the rear end surface of the platform 54. The sensor 62 is adjacent to the left stop 61. The tray 55 has 9 holes into which the lower part of the workpiece 6 is inserted. The platform 54 supports the tray 55 with the left and right end edges of the lower surface thereof supported by the upper surface of the 1 st fixing portion 45.

As shown in fig. 8, the inverted letter L-shaped attachment portion 54a is attached to the inside of each 1 st fixing portion 45 in a state where the short side portion of the letter L of the inverted letter L-shaped attachment portion 54a abuts against the lower surface of the platform 54. The 2 nd guide portion 53 is interposed between the long side portion of the letter L of the mounting portion 54a and the outer side surface of the movable portion 50. A 2 nd rack 63 is provided at a portion of the lower surface of the platform 54 corresponding to the pinion 52. The pinion gear 52 is engaged with the 2 nd rack 63. The platform 54 is guided by the 2 nd guide portion 53 and slides with respect to the movable portion 50. The amount of sliding of the platform 54 is doubled with respect to the amount of sliding of the movable portion 50 by the 1 st rack 49, the 2 nd rack 63, and the pinion 52.

As shown in fig. 7, a notch 45a is provided at a corner portion on the rear end edge side of the 1 st fixing portion 45, and an engaging portion 54b that engages with a tip end portion of the notch 45a is provided at a rear end portion of the platform 54. The platform 54 has an opening 54c (see fig. 11) in the center, and a 1 st receiving portion 56 is provided outside the edge of the opening 54 c.

As shown in fig. 8, 9, and 11, the 1 st receiving portion 56 has an inverted trapezoidal shape in front view, and an upper edge portion thereof is attached to the platform 54. In the 1 st receiving portion 56, the bottom portion is inclined downward as going from the front side toward the rear side, and the left and right side portions are inclined downward as going toward the inside. The rear portion of the 1 st receiving portion 56 is located rearward of the rear end portion of the platform 54. A cylindrical liquid trap portion 56a having an upper surface and a lower surface opened is provided at a substantially central portion of a rear end portion of a bottom portion of the 1 st receiving portion 56. Since the tray 55 has the hole 55a and the stage 54 has the opening 54c, the coolant adhering to the workpiece 6 falls down to the 1 st receiving portion 56. Since the 1 st receiving part 56 is inclined, the coolant falling down to the 1 st receiving part 56 is collected in the liquid collecting part 56 a. The 1 st receiving portion 56 slides together with the stage 54 with respect to the movable portion 50.

As shown in fig. 9, the 2 nd receiving portion 67 is attached to the frame 41k of the 1 st case 41 on the lower side of the back plate 41 h.

The 2 nd receiving portion 67 has a bottom plate 67a, a side plate 67b provided upright from the bottom plate 67a, and a mounting portion 67c connected to the side plate 67b on the rear side and mounted to the frame 41 k. The bottom plate 67a is inclined downward from the right side to the left side, and a cylindrical liquid trap portion 67d having an upper surface and a lower surface opened is provided at the left end of the rear portion of the bottom plate 67 a. The coolant that has fallen down toward the bottom plate 67a is collected in the liquid collection portion 67 d. The bottom plate 67a may be inclined downward from the front side toward the rear side. The coolant collected in the liquid collecting portion 56a falls down to the 2 nd receiving portion 67. Or may be sent to the 2 nd receiving unit 67 through a pipe (not shown). The liquid collecting unit 67d is connected to other pipes, and the coolant that has moved to the liquid collecting unit 67d is sent to the tray 71 of the 3 rd receiving unit 7. Alternatively, the liquid may be supplied to the liquid sump 8 by another pipe. The liquid collecting portion 67d is not limited to the left end provided at the rear portion of the bottom plate 67a, and may be provided at any position of the bottom plate 67 a.

The front plate 57 has a handle 57a at the center, and as shown in fig. 10, 12, and 13, the front plate 57 is connected to the side surface of the distal end side portion of the movable portion 50 by a connecting portion 64. The connecting portion 64 has a lateral plate portion 64c extending along the rear surface of the front plate 57, an upper plate portion 64d, and an abutting portion 64e abutting against the side surface, and has a long hole 64a extending in the front-rear direction at the abutting portion. The side surface is provided with female threads 50a, and a screw 64b penetrating the long hole 64a is fastened to the female threads 50 a.

As shown in fig. 6, wheels 59 and adjustment portions 60 are provided at four corners of the lower end portion of the 1 st case 41. The 1 st housing 41 can be moved forward, backward, leftward and rightward by the wheels 59, and after the 1 st housing 41 is disposed at a predetermined position, the height can be adjusted by the adjusting portion 60. The stopper 60 can suppress the motion of the wheel.

The 1 st case 41 and the 2 nd case 35 are different in front-rear length. As shown in fig. 1, the total front-rear length of the pullout portion 42 and the 1 st case 41 when the pullout portion 42 is pulled out to the front side is equal to or less than the front-rear length of the 2 nd case 35.

In the above conveyor 5, the handle 57a is pulled out from the state where the platform 54 is positioned at the rear portion of the 1 st housing 41, and the movable portion 50 slides with respect to the 1 st fixing portion 45 by the 1 st guide portion 51. The movable portion 50 slides in a supported state supported by the roller 47. With the rack-and-pinion configuration, the amount of sliding of the platform 54 is twice as much as that of the movable portion 50. As a result, the table 54 is projected from the cover plate 41c, and the tray 55 in which the workpiece 6 is fitted is placed on the table 54, which is in the state shown in fig. 1. Then, by pushing the front plate 57 toward the cover plate 41b (see fig. 6), the movable portion 50 slides along the 1 st fixed portion 45, and the platform 54 moves rearward. As shown in fig. 7 and 10, the rear end surface of the movable portion 50 abuts against the stopper 61, and the tip end portion of the notch 45a of the 1 st fixing portion 45 engages with the engagement portion 54b provided on the platform 54. This can suppress the forward and backward movement of the platform 54, and the drawer 42 cannot move forward and backward.

The sensor 62 is connected to the control device 19. When the sensor 62 detects the rear end surface of the platform 54, the control device 19 acquires information that the sensor 62 detects the rear end surface of the platform 54, and operates the conveyor 30. The arm 32 moves backward under the control of the controller 19, enters the 1 st housing 41 through the opening 41a, grips the workpiece 6 on the magazine 55, and takes out the workpiece 6 from the magazine 55. The arm 32 moves forward, enters the machine tool 1 through the opening 35a, and places the workpiece 6 on the table 20. The machine tool 1 machines a workpiece 6.

After the workpiece 6 is machined, the table 20 is moved toward the 2 nd housing 35 side, and the arm 32 grips the workpiece 6. The arm 32 moves backward, and the workpiece 6 is placed on the magazine 55. The next workpiece 6 is also machined in the same manner. When the machining of all the workpieces 6 on the magazine 55 is completed, the operator pulls out the front plate 57, and the table 54 projects from the cover plate 41c to exchange the workpieces 6.

During machining, the machine tool 1 sprays a coolant onto the workpiece 6 to cool the frictional heat. The coolant adheres to the workpiece 6, and when the workpiece 6 is taken out and put in between the machine tool 1 and the housing 4 by the arm 32, the coolant may flow down. When the workpiece 6 is taken in and out by the drawing portion 42, the coolant also flows down.

In the housing 4, the cooling liquid is collected by the 1 st receiving portion 56. The cooling liquid is collected by the 3 rd receiving portion 7 disposed below the conveyor 30 via the 2 nd receiving portion 67 disposed below the substrate 43. The cooling liquid is recovered to the liquid sump 8. Therefore, contamination due to the coolant falling on the floor of the installation space of the machine tool 1 can be suppressed. The coolant can be effectively used by recovery.

When the conveyor 30 is maintained, the conveyor 30 moves to the front side, and the operator removes any one of the cover plates 35b to 35 e. When the storage body 4 is to be maintained, any one of the cover plates 41b to 41g is removed. The cover plates 35b to 35e and the cover plates 41b to 41g are not limited to those that can be attached and detached. In addition to these cover plates, other removable cover plates may be provided. Each side of the 1 st case 41 and the 2 nd case 35 may not be divided into a plurality of cover plates.

Claims

1. A conveying apparatus, wherein,

the conveying device (5) comprises:

a conveyor (30) having an arm (32) that can grip a workpiece (6), the arm being movable between the inside and the outside of the machine tool (1); and

a receiving body (4),

the storage body is provided with:

a holding plate (55) that holds the workpiece and has a 1 st opening (55 a);

a movable part (50) which supports the holding plate and can slide through a guide part (51); and

and a 1 st receiving part (56) that receives the coolant below the 1 st opening.

2. The delivery device of claim 1,

the conveying device is provided with:

a housing (41) provided with a 2 nd opening (41a) for the arm to enter and exit;

a substrate (43) provided on the housing; and

and an attachment plate (44) attached to the substrate, wherein the attachment plate is provided with a fixing portion (45) extending in the front-back direction of the case.

3. The delivery device of claim 2,

the mounting plate and the substrate have a 3 rd opening (44a) and a 4 th opening (43c), respectively,

the conveying device is provided with a 2 nd receiving part (67) for receiving the cooling liquid at the lower side of the 4 th opening part.

4. The delivery device of claim 3,

the conveyor device has a 3 rd receiving portion (7) for receiving the cooling liquid on the lower side of the conveyor.

5. The conveying device according to any one of claims 1 to 4,

the 1 st receiving part, the 2 nd receiving part or the 3 rd receiving part has an inclined surface,

the inclined surface has a liquid collecting portion (56a, 67d, 75) that is open at the lower end thereof.