JPH0712917B2 - Forklift mast device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mast device for a forklift truck having a good front view.

(Prior Art) Conventionally, in a mast device of a forklift, various improvements have been made to improve the forward field of view. One of them is an inner mast having a U-shaped cross section inside an outer mast having a U-shaped cross section. A technique is known in which the blind spot due to the mast is reduced by storing and arranging. Examples of such cases include Japanese Patent Publication No. 49-49548.

In addition, as another method of improving the forward field of view, the upper tie beam of the inner mast is extended to the outside of the outer mast, and a chain wheel is attached to the extended portion so that the lift chain is arranged within the blind spot of the mast (or lift cylinder). That is, there is known a technique in which the lift chain is arranged so as to be behind the mast to prevent the view field from being obstructed by the lift chain. As such an example, for example, Japanese Utility Model Laid-Open No. 57-30296. Can be mentioned.

(Problems to be Solved by the Invention) By the way, when the above two techniques are combined, that is, when the inner mast is housed in the outer mast and the lift chain is arranged outside the mast, a good front view is obtained. It becomes possible.

When such a configuration is adopted, with respect to the upper part of the outer mast, the outer mast roller for receiving the forward moment of the inner mast, the rear liner for receiving the rearward moment of the inner mast, and the lateral moment of the inner mast are used. It is necessary to install the outer mast side roller and the chain support for connecting the lift chain.

And, specifically, in the case of the outer mast roller, it is necessary to arrange so as to roll the front outer surface of the inner mast,
It cannot be directly attached to the outer mast, and is therefore actually attached via a bracket. Further, in the case of the rear liner, a pin hole is formed in the rear flange portion of the outer mast, and the pin of the rear liner is fitted into the pin hole for attachment. On the other hand, in the case of the outer mast side roller, the roller pin is directly assembled to the outer mast by fixing it with bolts while being fitted in the opening formed in the outer mast, and the chain support is attached to the side surface of the outer mast by welding. That is, each component would normally be assembled individually to the outer mast.

However, the mast material is generally a roll-formed product or a heat-extruded product, which is a long product that is considerably long in the axial direction and a heavy product. Therefore, as described above, the mast roller,
Installing the rear liner, side rollers and chain support individually is a very tedious task. In other words, it is necessary to form an opening by fusing and a pin hole or a screw hole by machining in the outer mast, and in particular, it is necessary to invert the mast to process the pin hole and the screw hole having different directions. It is troublesome to handle, and there are manufacturing problems such as high cost.

Therefore, in the present invention, on the premise of adopting the configuration for improving the forward visual field as described above, the mounting portions of the respective components individually mounted with respect to the upper end of the outer mast are collectively formed in one bracket, and It is an object of the present invention to provide a forklift mast device improved by avoiding or reducing machining of the master mast and easily mounting the outer mast by mounting the bracket on the upper end of the outer mast.

(Means for Solving the Problems) The present invention is configured as follows to solve the above problems.

That is, the forklift mast device according to the present invention is configured such that an inner mast having a U-shaped cross section is vertically movably housed in an outer mast having a U-shaped cross section, and a lift chain is disposed on an outer surface of the outer mast. The outer mast roller and outer mast side rollers are mounted on the upper end of the outer mast for guiding the inner mast, and the chain support as a lift chain mounting part to which one end of the lift chain is connected. The roller mounting bracket is formed separately from the above, and is fixed to the upper end portion of the outer mast in an upright state by welding.

(Operation) According to the mast device of the present invention, the roller mounting bracket having the three mounting portions as described above can be attached to the outer mast by welding, so that the machining of the outer mast is significantly reduced. On the other hand, the roller mounting bracket can be molded by forging or casting, which allows the openings and holes required for mounting the roller and lift chain to be molded simultaneously during forging or during casting, and also for screws. With respect to machining such as holes, the roller mounting bracket itself is a small item compared to the outer mast, which makes handling at the time of processing much easier.

(Example) Hereinafter, the Example of this invention is concretely described based on drawing. First, a visual field improving mast device will be described with reference to FIGS. 3 and 4. The pair of left and right outer masts 1 are formed in a U-shaped cross section, and the left and right inner masts 2 also formed in the U-shaped cross section are accommodated in the U-shaped space so as to be vertically movable.

An outer mast roller 3 that rolls on the front outer surface of the inner mast 2 is mounted on the front side of the upper end of the outer mast 1, and an inner mast roller that rolls on the inner rear surface of the outer mast 1 is arranged on the inner rear side of the lower end of the inner mast 2. A mast roller 4 is rotatably mounted via a roller bracket 5 and a roller pin 6, and receives a forward moment acting on the inner mast 2 by these mast rollers 3 and 4. The details of mounting the outer mast roller 3 will be described later.

A rear liner 7 slidably abutting the rear outer surface of the inner mast 4 is attached to the inner rear surface of the upper end of the outer mast 1, while the front inner surface of the outer mast 1 is slidable to the outer surface of the lower end of the inner mast 2. A front liner 8 that abuts against the inner mast 2 is subjected to a rearward moment by the liners 7 and 8. Both liners 7 and 8 are, as shown in FIG.
It is attached by inserting the pin 9 provided on 7, 8 into the pin hole 10 formed on the mast side.

Further, the inner mast 2 is provided on the upper end side of the outer mast 1.
An outer mast side roller 11 rolling on the outer side surface of the inner mast 2 is mounted, while an inner mast side roller 12 rolling on the inner side surface of the outer mast 1 is mounted on the front side of the lower end of the inner mast 2. Side roller 1
1,12 receives a lateral moment acting on the inner mast 2. The inner mast side roller
As shown in FIG. 5, a roller pin 13 is fixed by a bolt 14 in a state where the roller pin 13 is inserted into the outer mast 1 side through a vertically long opening penetrating the inner mast 2. On the other hand, the details of mounting the outer mast side roller 11 will be described later.

As shown in FIG. 3, lift cylinders 15 are erected at the rear of the left and right outer masts 1, and the lower ends of the lift cylinders 15 are attached to the outer mast 1 via brackets (not shown) or the lower cross of the outer mast 1. Beam 1a
The upper end of the piston rod 16 is connected to the upper tie beam 2a of the inner mast 2.

The upper tie beam 2a is extended so as to wrap around the outer mast 1, and a chain wheel 17 is attached to the extended portion with the center of rotation thereof in the left-right direction.

Then, the lift chain 18 hung on the chain wheel 17
Is connected to the chain support 19 of the outer mast 1 at the rear end passing through the rear side of the chain wheel 17.
A front end passing through the front side of is connected to a chain support 22 of a lift bracket 21 that moorably supports the fork 20.
That is, the front portion of the lift chain 18 that is continuous with the lift bracket 21 is arranged using the projection plane in the front-rear direction with respect to the outer mast 1. The lift bracket 21 is moved up and down via a lift roller 23 that is rollably arranged in the U-shaped space of the inner mast 2. In FIG. 3, 1b is an upper cross beam of the outer mast 1 and 2b is a lower tie beam of the inner mast 2.

In the mast device configured as described above, the outer mast 1 and the inner mast 2 which are front view obstructing members overlap with each other, and the lift cylinder 15 is arranged behind the mast. Is the sixth
It is limited to the narrow range indicated by the diagonal lines in the figure. Then, the lift chain 18 is arranged close to the mast so as to be within the dead zone indicated by the diagonal lines as shown in the figure, which is an effective arrangement for preventing the obstruction of the forward visual field.

Next, in the forward improved mast device configured and functioning as described above, mainly the outer mast roller 3 mounted on the upper end of the outer mast 1, the outer mast side roller 11, and the chain support 19 are mainly attached. A description will be given based on FIG. 1 and FIG.

As shown, the rollers 3 and 11 are mounted on the upper end of the outer mast 1 via a roller mounting bracket 24, and the chain support 19 is formed integrally with the roller mounting bracket 24. That is, the roller mounting bracket 24 is made of a forged product or a cast product, is formed in a substantially rectangular plate shape slightly larger than the front-rear width of the outer mast 1, and has a mast roller mounting portion 25 at the front upper end portion and a slightly rearward center portion. Side roller mounting part 31, and both mounting parts 25, 31
Chain supports 19 as lift chain mounting portions are formed on the outer surfaces of the spaces.

The mast roller mounting portion 25 includes a roller mounting hole 26 and screw holes 27 for mounting the roller protective cover on both sides of the roller mounting hole 26.
A roller pin 29 for rotatably supporting the outer mast roller 3, the roller mounting hole 26, and a roller protection cover.
While inserting and fixing it through the 28 through holes, a roller protection cover
The outer mast roller 3 is mounted by fastening 28 to the screw hole 27 with a bolt 30.

Further, the side roller mounting portion 31 is provided with a vertically long opening 32 for mounting the roller, and screw holes 33 on both sides of the opening 32,
The outer mast side roller 11 is inserted from the outside into the opening 32, and the roller pin 34 is fastened to the screw hole 33 with a bolt 35 to mount the outer mast side roller 11. Furthermore, the chain support 19 that is the lift chain mounting portion has a circular vertical hole 36, through which the anchor bolt 37 fixed to the end of the lift chain 18 is inserted and tightened with a nut 38. It is designed to be attached.

Then, the roller mounting bracket 24 having the above-described structure
The lower edge portion of the is vertically fixed to the upper edge portion of the outer mast 1 by welding. In this case, the upper edge portion of the outer mast 1 is cut off by fusing, leaving the rear flange portion as the liner mounting portion, and the lower edge and the rear edge of the roller mounting bracket 24 are welded to this cutout portion. On the other hand, the uncut portion is effective in obtaining a wide welding surface and increasing the welding strength, and moreover, the dimension management regarding the liner mounting becomes easier as compared with the case where the liner mounting portion is manufactured on the roller mounting bracket 24 side. . Further, in this embodiment, a substantially L-shaped member 39 is fixed to the outer surface of the upper end of the outer mast 1 by welding, and the upper cross beam 1b is also fixed thereto by welding.

In the present embodiment configured as described above, with respect to the long and heavy outer mast 1 which is a roll-formed product or a heat-extruded product, the roller mounting bracket 24 is attached to the upper end side thereof. Only the surface and the pin hole 10 for attaching the liner need be formed. Therefore, the number of machining is reduced as compared with the conventional one, and particularly regarding the hole machining, the liner pin holes 10 are only formed in the same direction, which means that the outer mast which is necessary when there are holes in different directions. There is no need to perform the reversal work of 1.

On the other hand, since the roller mounting bracket 24 can be manufactured by forging or casting, the roller mounting hole 26
The opening 32, the chain support 19 and the like can be formed at the same time during forging or casting,
And even if the screw holes 27 and 33 are processed, the outer mast 1
Since the roller mounting bracket itself is very small compared to, the handling during processing becomes easy.

(Effects of the Invention) As described in detail above, according to the present invention, when the inner mast is housed in the U-shaped space of the outer mast and the lift chain is arranged outside the mast, the inner mast guiding mast is adopted. By configuring each roller, side roller, and lift chain mounting part to be integrally formed on one roller mounting bracket that is separate from the mast, the number of machining operations for the outer mast, which is a long and heavy object, can be reduced. The number can be reduced, and the roller mounting bracket can be manufactured by forging or casting, and can be easily machined, which is extremely effective for improving the manufacturability.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show an embodiment of the present invention, FIG. 1 is a perspective view from the outer rear side of the outer mast showing the roller and lift chain mounting structure to the upper end of the outer mast, and FIG. 2 is the inner rear side of the outer mast. FIG. 3 is a plan view of the mast device shown by cutting the right half, FIG. 4 is a view taken in the direction of arrow A in FIG. 3, and FIG. 5 is a mounting structure of the liner and the inner mast side roller. FIG. 6 is a cross-sectional view and FIG. 6 is an explanatory view showing a front visual field obstruction area by the mast device. 1 ... Outer mast, 2 ... Inner mast 11 ... Outer mast Side roller 18 ... Litho chain, 19 ... Chain support 24 ... Roller mounting bracket 25 ... Mast roller mounting part 31 ... Side roller mounting part

Claims (1)

[Claims] 1. A mast device having an inner mast having a U-shaped cross section so as to be vertically movable in an outer mast having a U-shaped cross section, and a lift chain disposed on an outer surface of the outer mast, for guiding the inner mast up and down. As a separate body from the outer mast, the outer mast roller and outer mast side roller roller mounting portions arranged at the upper end of the outer mast and the chain support as a lift chain mounting portion to which one end of the lift chain is connected are separately provided. The mast device for a forklift in which the roller mounting bracket is formed on one of the above, and the roller mounting bracket is fixed to the upper end portion of the outer mast in an upright state by welding.