JP3523792B2 - Cabin frame structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a skeleton structure of a cabin used in a work vehicle such as a backhoe.

[0002]

2. Description of the Related Art For example, a frame structure of a cabin in a backhoe has a cabin main body and a roof, and the cabin main body has a pair of left and right front columns supporting a front glass, and a door is arranged between the one front columns. And a middle strut, and upper and lower horizontal beams connecting the upper and lower ends of the one front strut and the middle strut,
The left and right front stanchions of the cabin body are disclosed in JP-A-8-29153.
As disclosed in Japanese Patent Publication No. 7, two plate members, an inner plate and an outer plate, are formed by swelling inward and outward by pressing and pasting them together.
The middle strut and the rear strut are also separately formed with the same structure, and these strut are connected by upper and lower lateral beams.

[0003]

In the above-mentioned prior art, since each of the columns and the lateral beams are individually pressed by two plates, the material cost is low, but they must be welded to each other. In addition, the manufacturing cost is high, and there is a problem in that it is difficult to secure strength as well as welding distortion occurs. It is also difficult to make roofs. An object of the present invention is to provide a skeleton structure of a cabin that can solve such problems.

According to the present invention, a pillar and a lateral beam on the door side are punched out from two large inner and outer plate materials by a portion corresponding to a door arrangement space and bonded together to form a front strut forming portion, a middle strut forming portion, and a vertical cross beam forming portion on the door side. It is an object of the present invention to provide a skeleton structure of a cabin in which the strength is secured and the structure can be manufactured at low cost by forming the other front column by using a pipe material. The present invention provides a frame structure for a cabin that secures strength and can be manufactured at low cost by forming a lateral member on the door side of the roof by laminating and forming the other lateral member by a pipe material. To aim.

[0005]

A first concrete means for solving the problems in the present invention is a cabin body 4 and a roof 5.
The cabin body 4 has a pair of left and right front columns 8 for supporting the front glass 6, an intermediate column 9 for arranging the door 7 between the front columns 8 on the door side, and the front columns 8 on the door side. In the cabin having the upper and lower horizontal beams 11 and 12 connecting the upper and lower ends of the intermediate support column 9, the cabin body 4 is formed by punching out a portion 17A corresponding to the door arrangement space from the two inner and outer plate members 15 and 16 and leaving the remaining portion inside and outside. By bulging , the front strut forming portion 8A on the door 7 side, the midway strut forming portion 9A, and the upper and lower horizontal beam forming portions 11A and 12A are formed by this swelling , and the other front strut 8 is formed of a pipe material. is there.

[0006] As a result, the inner and outer bulges 2 formed by bulging in and out.
When the plate members 15 and 16 are bonded together, the front strut forming portion 8A, the middle strut forming portion 9A, and the upper and lower horizontal beam forming portion 1 on the door 7 side are attached.
1A and 12A are integrally formed, and the other front strut 8 is easily formed of a pipe material, which is extremely easy to manufacture and ensures strength. A second specific means for solving the problems in the present invention has a cabin body 4 and a roof 5, and the cabin body 4 is curved so as to gradually retract from the lower portion to the upper portion and supports the windshield 6. A pair of left and right front columns 8 and a middle column 9 for arranging the door 7 between the front columns 8 on the door side;
It has a rear pillar 10 for arranging a rear glass 13 between the middle pillar 9 and upper and lower horizontal beams 11 and 12 for connecting the upper and lower ends of the front pillar 8 on the door 7 side, the middle pillar 9 and the rear pillar 10. in the cabin, the cabin body 4, bulges door arrangement space equivalent punched 17A and a rear side glass configuration space equivalent 17B and the remainder by pressing the inner and outer plate members 15 and 16 in and out, the Rise Door 7 by coming out
That is, the front strut forming portion 8A, the middle strut forming portion 9A, the rear strut forming portion 10A, and the upper and lower horizontal beam forming portions 11A and 12A are formed on the side, and the other front strut 8 is formed of a pipe material.

As a result, even if the left and right front columns 8 are curved so as to gradually retreat from the lower part to the upper part, when the two press-formed inner and outer plate members 15 and 16 are stuck together, the door 7 The front strut forming portion 8A, the midway strut forming portion 9A, and the upper and lower horizontal beam forming portions 11A and 12A are integrally formed, and the other front strut 8 is easily formed of a pipe material, which is extremely easy to manufacture and has high strength. Reserved. A third concrete means for solving the problem in the present invention is a cabin body 4
And a roof 5, and the roof 5 includes left and right lateral members 18, 19 and front and rear members 2 for connecting front and rear ends of the left and right lateral members 18, 19.
0, 21, the left and right lateral members 18, 19 and the front and rear members 2
In the cabin having the inner and outer roof members 22 and 23 attached to 0 and 21, and the lateral member 18 on the door 7 side gradually widens from the front and rear ends to the middle part, the roof 5
Is a swelling of two plate members 24 and 25 inside and outside
Out by forming a transverse member 18 of the door 7 side is that which forms the other transverse member 19 by tubing.

As a result, the inside and outside 2 which are bulged in and out
When the plate members 24 and 25 are pasted together, the lateral member 1 on the door 7 side is gradually widened from the front and rear ends to the middle part.
8 is easily formed, and the other lateral member 19 is also easily formed of a pipe material, which is extremely easy to manufacture and ensures strength. A fourth concrete means for solving the problems in the present invention has a cabin body 4 and a roof 5, and the cabin body 4 is curved so as to gradually retract from the lower part to the upper part, and is openable upward. A pair of left and right front columns 8 for supporting the glass 6,
Middle support 9 for arranging the door 7 between the front support 8 on the door side
And the upper and lower horizontal beams 11 and 12 connecting the upper and lower ends of the front pillar 8 on the door side and the middle pillar 9, and the roof 5 connects the left and right lateral members 18, 19 and the front and rear ends of the left and right lateral members 18, 19. The front and rear members 20 and 21 to be connected and the left and right lateral members 18 and 19
And the inner and outer roof members 2 attached to the front and rear members 20, 21
In the cabin having 2 and 23, the cabin body 4 punches out a portion 17A corresponding to the door placement space by press working from the two inner and outer plate members 15 and 16, and bulges the remaining portion inward and outward, and the bulge causes the door to open. Front strut forming part 8 on 7 side
A, midway pillar forming portion 9A, and upper and lower horizontal beam forming portions 11A, 12
Forming a A, to form the other front support 8 in the tubing, the roof 5, come to bulge the inner and outer plate members 24 and 25 in and out
Bulged by forming a transverse member 18 of the door 7 side, to form the other transverse member 19 with tubing, and the lower of the inner and outer plate members 24, 25 of the upper and the roof 5 of the inner and outer plate members 15, 16 of the cabin body 4 And the upper end of the pipe material of the cabin body 4 and the front end of the pipe material of the roof 5 are connected to each other, and the front column forming portion 8 on the door 7 side is connected.
A rail part 2 for opening and closing the front glass 6 on each of the inner plates 15 and 24 of the horizontal member 18 and the pipe members facing them, from the front closed position to the substantially horizontal open position.
That is, 6 and 27 are integrally molded.

As a result, when the two press-formed inner and outer plate members 15, 16, 24, and 25 that bulge inward and outwardly are pasted together, the front strut forming portion 8A, the middle strut forming portion 9A, and the upper and lower horizontal beams on the door 7 side. The forming portions 11A and 12A are integrally formed, and the lateral member 18 is also formed.
Also, the lateral member 19 is easily formed of a pipe material, and the mounting of the cabin body 4 and the roof 5 and the formation of the rail portions 26 and 27 are facilitated, and the manufacture is extremely simple and the strength is secured.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 4, a back hoe 1 is illustrated as an example of a work vehicle, and the back hoe 1 has a cabin 2 mounted on a back hoe main unit 3. The backhoe main unit 3 is a traveling body 3 having a crawler traveling device 31.
A swivel base 33 is rotatably mounted on the swivel base 2, and a working unit 34 having a work tool such as a bucket at the tip of the boom is mounted on the swivel base 33. It shows a small rear turning type that fits within the range of the left and right outer ends.

A driver's seat 35, an engine, a hydraulic pump, a hydraulic oil tank 36, a control valve unit 37, etc. are mounted on the swivel base 33, 38 is an openable / closable bonnet, 39 is a tank cover, and 40 is an engine cover. The driver's seat 35 has an engine cover 40.
Supported above. The cabin 2 mounted on the swivel base 33 so as to surround the driver's seat 35 is roughly divided into a cabin body 4 and a roof 5. The cabin body 4 is provided on the front glass 6 on the front side and on the side opposite to the tank cover 39. Door 7 provided
And have.

The front surface of the cabin body 4 is curved so as to gradually retract from the lower portion to the upper portion, and therefore the door 7
The front edge of the is also curved (three-dimensional curved shape) so that the upper part thereof recedes. In the following description, the left-right direction and the front-back direction are based on the driver sitting in the driver's seat 35. The cabin body 4 has a door 7 disposed between a pair of left and right front columns 8L and 8R that are curved so as to gradually retract from the lower portion to the upper portion and support the front glass 6 and the front column 8L on the door side. The middle pillar 9 and the left pillar 10L on which the rear glass 13 is arranged between the middle pillar 9 and the front pillar 8 on the right side.
R, the front pillar 8L on the door 7 side, the middle pillar 9, and the upper and lower horizontal beams 11 and 12 connecting the upper and lower ends of the rear pillar 10L.

The front glass 6 is provided to open and close a front window formed in the upper half between the left and right front columns 8L and 8R, and can be moved rearward and upward to a storage position below the roof 5, and the left and right front columns are supported. The lower half between 8L and 8R is provided with a fitting front lower glass 43, and the rear glass 13 is also fitting, and the right side wall portion 42 has a sliding window glass 44 above the tank cover 39. Is provided. A rear glass 45 is provided between the left and right rear columns 10L and 10R, and upper and lower ends of the right front column 8R and the rear column 10R are connected by upper and lower horizontal beams.

1 to 11, the cabin body 4 is shown.
Front strut 8R on the door 7 side (left side portion), middle strut 9L,
The rear column 10L, the upper and lower horizontal beams 11, 12 and the like are integrally formed by sheet metal. That is, two inner and outer plate members 15 and 16 having substantially the same shape are pressed to punch a portion 17A corresponding to a door arrangement space and a portion 17B corresponding to a rear glass arrangement space (FIG. 4, FIG.
(Shown in FIG. 10), and the remaining portion is curved in an arc shape in plan view,
In addition, it bulges inward and outward (mainly the inner plate 15 inward and the outer plate 16 outward), and the bulged both plate members 15 and 16 are bonded to each other to form a hollow square member, and the front strut forming portion 8A and the middle part are formed. The pillar forming portion 9A, the rear pillar forming portion 10A, and the upper and lower horizontal beam forming portions 11A and 12A are formed, and the front pillar 8R and the middle pillar 9 are formed.
L, rear pillar 10L, upper and lower horizontal beams 11, 12 and the like.

The remaining portions of the two plate members 15 and 16 after punching have a three-dimensional curved shape in order to form a bulge and an upward retreat of the front edge portion. However, the upper horizontal beam 11 is combined with the left lateral member 18 of the roof 5 to form a substantially hollow square bar shape, and the lower horizontal beam 12 embraces the square tube member 51 or the square tube member 5
Combined with No. 1, it becomes a substantially hollow square bar shape. The plate members 15 and 16 are spot-welded at the bonded portions, and the periphery of the door arrangement space 17A and the rear glass arrangement space 17B are covered with a sealing material or the like.
The rear glass 1 is provided in the space 17B corresponding to the rear glass arrangement space.
3 is fitted, and a weather strip around the door 7 can come into contact with the peripheral edge of the door placement space 17A.

The door-side front support column 8L is a laminated plate and has a deformed tubular shape in section, and a groove-shaped rail portion 26 for guiding the front glass 6 is formed on the front glass 6 side. The front end and the rear end on the side are double bonded parts. The middle support column 9 and the rear support column 10L are in the shape of a square tube, and the rear part of the door 7 is pivotally supported on the middle support column 9 through a pair of upper and lower pivot support members 47 fixed to the outer surface. In this door 7, necessary members such as a pivot support 47, a handle and a lock lock 48, and a striker 49 are directly fixed to the glass plate 6a, but a metal plate is attached to the inner surface of the glass plate 6a, and the above-mentioned necessary members are attached to the metal plate. A member may be fixed, or a metal frame may be provided around the glass plate 6a, and a necessary member may be attached to the metal frame. Reference numeral 50 is a receiver of the striker 49.

The right front support column 8R is formed of a curved deformed tube. This deformed pipe is formed by pulling out a circular pipe material to form a groove-shaped rail portion 26 and a joining portion 8 formed by folding the rail portion 26 into front and rear front and rear ends.
a, 8b are formed, the rail portion 26 has improved hardness due to the U-shaped bending, and the front and rear mating portions 8a, 8b have a double structure, so that the rail portion 26 can be reinforced. Moreover, the front mating portion 8a serves as an abutting surface of the front glass 6, and the rear mating portion 8b can also serve as a seal mounting portion for the sliding glass 44.

The rear support column 10R is formed by pressing and bonding two plates together to form the mounting portion for the rear glass 45, but the rear support glass 45 mounting plate is fixed to a deformed tube similar to the front support column 8R. May be. In addition, the rear support column 10R may be formed by punching and expanding two plates in the same manner as the left rear support column 10L and the upper and lower horizontal beams 11 and 12. It is arranged. 1 to 3, 6, 7, 9, and 12, the roof 5 includes the left and right lateral members 18, 19 and the left and right lateral members 18, 1.
The front and rear members 20, 21 connecting the front and rear ends of the front and rear members 9, and the left and right lateral members 18, 19 and the inner and outer roof members 22, 23 mounted on the front and rear members 20, 21 are provided. The width gradually increases from the front and rear ends to the middle part.

The left lateral member 18 on the door 7 side of the roof 5 is
While the inner surface is linear along the front-rear direction, it is difficult to form it with a pipe material because the outer surface protrudes outward. Therefore, the two inner and outer plate members 24 and 25 are braked and pressed. Etc., the inner plate 24 bulges inward, and in particular, the width of the bottom wall 24a is widened in the middle part from the front and rear ends, and the outer plate 25 bulges outward. In particular, the roof 5 has a rounded shape, and both plate members 24 and 25 are formed together through the upper ends of the plate members 15 and 16 and the outer roof member 23.

On the other hand, since the right lateral member 19 is a straight line along the front-rear direction, a pipe material can be used, and a deformed pipe having the same cross-sectional shape as the front support column 8R is used. The part 27 is formed. The front end of the left lateral member 18 is joined to the upper end of the front support column 8L.
Left rail part 2 in which the roller 62 is rotatably engaged
6, 27 are continuous, the front end of the right lateral member 19 is joined to the upper end of the front support column 8R, and the right rail portions 26, 27 are connected.
Are continuous, and the front glass 6 can be freely changed from a substantially vertical frontward closed posture to an upward substantially horizontal opened posture.

The lower portion 26a of the rail portion 26 is gently inclined to the front side, and the upper end (front end of the rail portion 27) 26b of the rail portion 26 projects slightly forward, so that the front portion when in the closed posture (front posture). Around the glass 6 the left and right front columns 8L,
Weather strip 52 attached to 8R and front member 20
Cushions 53 are provided at the lower end and the upper end of the rail portion 26 and at the rear end of the rail portion 27 to cushion the collision of the roller 62 of the windshield 6. The right front column 8R has a curved shape in which the upper part recedes, and the lateral member 19 has a substantially linear shape, which can be formed by only two-dimensionally bending the deformed pipe, and by bending one deformed pipe,
It is also possible to integrally form the front column 8R and the lateral member 19.

The outer roof member 23 and outer plate 25 are
It is also possible to form a single plate and fix the inner plate 24 thereto. The front portion of the outer roof member 23 is cut away, and a transparent or translucent plastic plate is fitted into the front window 46.
Are formed. 2 to 6 and 12 to 15, the front glass 6 constitutes a front window device that opens and closes by moving up and down the upper half of the front surface of the cabin 2. A support bracket 61 is directly fixed to the four corners of the glass plate 6a, and a support shaft 63 of a roller 62 rolling in the rail portions 26 and 27 is supported by each of the support brackets 61. The opening / closing handle 65 is also directly attached to the glass plate 6a.

Left and right support brackets 6 on the front glass 6
1, a support plate 66 and a support cylinder 67 are fixed,
A lock member 68 formed of a pin is inserted in the support cylinder 67 so as to be slidable in the left-right direction. A handle 69 is attached to the lock member 68, and a U-shaped position setting groove 67 a for setting the left and right positions of the handle 69 is provided on the support cylinder 67.
By moving the handle 69 in the left-right direction and then rotating the handle 69, the left-right movement of the lock member 68 is restricted at the projected position or the retracted position.

The lock member 68 is movable in the axial direction by holding the handle 69 so that the lock member 68 can be retracted outward from the front glass 6 to the left and right, and an engaging member 70A having a hole for engaging with the lock member 68 is formed. , 70B are attached to the upper ends of the left and right front columns 8 and the rear ends of the left and right lateral members 18, 19, as shown in FIG. Therefore, the lock member 68 can be engaged with the engagement member 70A in the state where the front glass 6 is in the forward closed position, the lock member 68 is disengaged from the engagement member 70A via the handle 69, and the handle 65 is held. The front glass 6 can be held in the closed posture by engaging the locking member 68 with the engaging member 70B in a state where the front glass 6 is lifted and the posture is changed to the open posture.

On the left support bracket 61 of the front glass 6 or the support plate 66 fixed to the left support bracket 61, a latch pin 71 is projected outward to the left, and a latch lever 72 for engaging with this is provided on the left lateral member 1.
8 is provided. The engaging lever 72 is rotatably supported via a shaft on a bracket 73 provided on the rear portion of the left lateral member 18, and is engaged on the side opposite to the grip portion 72a.
1b by a biasing means such as a coil spring (not shown).
It is biased in the clockwise direction, and the stopper restricts the clockwise rotation beyond the solid line state.

When the front glass 6 is moved to the open posture and the lock member 68 reaches the position facing the hole of the engaging member 70B, the latch pin 71 pushes the latch lever 72 counterclockwise. Later, it engages with the engaging portion 72b on the rear side.
Since the roller 62 presses the cushion 53 when the front glass 6 is in the open position, the restoring force of the cushion 53 tries to shift the front glass 6 slightly to the front side from the normal open position, but the latch pin 71 causes the latch lever 71 to move. 72 engagement part 72b
By engaging with the lock member 68, the shift can be prevented, and the lock member 68 can be held at the engageable position with respect to the engaging member 70B, so that the lock member 68 can be easily engaged.

The lock member 68, the engaging member 70B and the like serve as the main locking means for the front glass 6, and the latching pin 71, the latching lever 72 and the like serve as the temporary locking means, whereby the front glass 6 is secured to the rail portions 26, 27. And a lock mechanism 74 which holds the forward closed posture and the upward open posture and limits the posture change. When releasing the lock mechanism 74 when the front glass 6 is in the open posture, the lock member 68 is disengaged from the engaging member 70B via the handle 69, and the engaging lever 72 is rotated to engage the engaging portion 72b. Remove from the pin 71. Then, the front glass 6 is displaced in the forward direction by the elastic force of the cushion 53, and even if the hand is released from the engagement lever 72, the engagement pin 71 does not engage with the engagement portion 72b.

The present invention is not limited to the above embodiment, but can be variously modified. For example,
The cabin 2 can be applied to backhoes of types other than the small rear swing type, work vehicles other than backhoes such as tractors,
An air conditioner unit may be arranged between the inner and outer roof members 22 and 23. The right side wall portion 42 may be a fit-in type glass instead of the sliding glass, and the door 7 may be a foldable type that bends in the middle of the front and rear. Further, the front window device may be configured to open and close by pulling the front glass 6 to the front side of the lower front glass 43.

[0029]

According to the present invention described in detail above, when two inner and outer swelled plate members are bonded together, the front strut forming portion 8A and the middle strut forming portion 9A on the door 7 side of the cabin body 4 are attached. The upper and lower lateral beam forming portions 11A and 12A can be integrally formed, and the lateral member 18 on the door 7 side of the roof 5 which is gradually widened from the front and rear ends to the middle portion can be easily formed. The front columns 8 and the lateral members 19 are also easily formed of a pipe material, which is extremely easy to manufacture and ensures strength, and the cabin body 4 and the roof 5 can be easily mounted and the rail portions 26 and 27 can be easily formed.

[Brief description of drawings]

FIG. 1 is a side view of a backhoe showing an embodiment of the present invention.

FIG. 2 is a front view of the backhoe.

FIG. 3 is a plan view of the backhoe.

FIG. 4 is a cross-sectional view taken along line XX of the cabin of FIG. 1 showing a main part of the present invention.

FIG. 5 is an enlarged cross-sectional view of the front portion of the cabin.

6 is a cross-sectional view taken along line YY of FIG.

7 is a sectional view taken along line ZZ in FIG.

FIG. 8 is an enlarged cross-sectional view of a door pivot portion.

9 is A, B, C, D are W1, W2, and FIG.
It is sectional drawing of the W3 and W4 line position.

FIG. 10 is a side view of the cabin body.

11 is a cross-sectional view taken along the line SS of FIG.

12 is a sectional view taken along line TT of FIG.

FIG. 13 is a front view of a front glass.

FIG. 14 is a side view showing a lock mechanism of a windshield.

FIG. 15 is a partial cross-sectional front view of the lock mechanism.

[Explanation of symbols]

1 backhoe 2 cabins 4 cabin body 5 roof 6 front glass 7 doors 8 front support 8A Front strut forming part 9 Midway support 9A Midway support formation part 10 Rear support 10A Rear strut forming part 11 Upper horizontal beam 11A Upper horizontal beam forming part 12 Lower horizontal beam 12A Lower horizontal beam forming part 13 Rear glass 15 inner plate 16 Skin 18 Left lateral member 19 Right lateral member 20 Front member 21 Rear member 22 Inner roof member 23 Outer roof member 24 inner plate 25 outer plate 26 Rail section 27 Rail section

─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Etsuro Sasaki 334-2, Naganuma-cho, Inage-ku, Chiba-shi, Chiba Ninomiya Sangyo Co., Ltd. (72) Yoshio Sakuma 334-2, Naganuma-cho, Inage-ku, Chiba, Chiba Prefecture Miya Sangyo Co., Ltd. (56) Reference JP-A-9-60043 (JP, A) JP-A-8-291537 (JP, A) Actually open 8-283 (JP, U) Actually open 6-87462 ( (58) Fields investigated (Int.Cl. ⁷ , DB name) E02F 9/16

Claims (3)

(57) [Claims] 1. A cabin main body having a roof and a roof main body, wherein the cabin main body has a pair of left and right front columns supporting a front glass, a midway column for arranging a door between the front columns on the door side, and the door side. In a cabin having a front strut and upper and lower horizontal beams connecting the upper and lower ends of a middle strut, the door side of the cabin body punches out a portion corresponding to the door arrangement space from two plate members inside and outside, and bulges the remaining portion inward and outward, top and front post forming part and the middle pillar forming portion by the expanded
Form a part of the upper horizontal beam forming part of the horizontal beam and a part of the lower horizontal beam
To form a lower horizontal beam forming portion, to form a horizontal member of the roof by providing a horizontal member of the roof in the upper horizontal beam forming portion,
A skeleton structure of a cabin, characterized in that a square tube member is provided in the lower horizontal beam forming portion to form a lower horizontal beam having a substantially hollow square shape. 2. A pair of left and right front columns for supporting the windshield and a front column on the door side, each having a cabin body and a roof, and the cabin body is curved so as to gradually retract from a lower portion to an upper portion. A cabin having an intermediate strut for arranging a door at, a rear strut for arranging a rear glass between the middle strut, and a vertical cross beam connecting the upper and lower ends of the front strut, the intermediate strut and the rear strut on the door side. In the door side of the cabin body, two door plates, the inner and outer plates, are pressed to punch out a portion corresponding to the door placement space and a portion corresponding to the rear glass placement space and bulge the remaining portion inward and outward. Forming part, midway strut forming part, rear strut forming part and part of upper cross beam forming part of upper cross beam and lower cross beam
Forming a lower horizontal beam forming part, forming a horizontal member of the roof in the upper horizontal beam forming part to form an upper horizontal beam in the shape of a substantially hollow square member, and providing a square tube member in the lower horizontal beam forming part to form a substantially hollow square member. A skeleton structure of a cabin characterized by forming a lower transverse beam of a shape. 3. A pair of left and right front columns for supporting a front glass that has a cabin body and a roof, and the cabin body is curved so as to gradually retract from a lower portion to an upper portion, and a pair of front columns on the door side. A midway strut for arranging a door between the front strut and a front strut on the door side and upper and lower horizontal beams connecting the upper and lower ends of the middle strut are provided, and the roof has left and right lateral members and front and rear ends of the left and right lateral members. In a cabin having front and rear members to be connected and inner and outer roof members mounted on the left and right lateral members and the front and rear members, the cabin body is punched from a plate material of two sheets inside and outside by punching a portion corresponding to a door arrangement space and a remaining portion. Bulge inward and outward, and by this bulge, the front column forming part on the door side, the intermediate column forming part, and the upper horizontal beam forming part and the lower horizontal beam forming a part of the upper horizontal beam.
A lower horizontal beam forming part that forms a part of the beam is formed, and the other front column is formed of a pipe material, and the roof bulges two plate members inside and outside, and the bulge expands laterally on the door side. A member is formed, the other lateral member is formed of a pipe material, and the upper lateral beam forming portion of the inner and outer plate members of the cabin body and the lateral member of the inner and outer plate members of the roof are fixed to each other to form a substantially horizontal square beam-shaped upper lateral beam, A square tubular member is provided in the lower lateral beam forming portion of the inner and outer plate members to form a substantially horizontal rectangular beam-shaped lower lateral beam, and the upper end of the tubular member of the cabin body and the front end of the tubular member of the roof are connected to each other, and the front strut forming portion on the door side is formed. And rails for integrally opening and closing the front glass from the forward closed position to the substantially horizontal open position on the facing surfaces of the inner plates of the lateral members and the pipe members facing them. Cabin frame structure.