JP2591598B2 - Table lift equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a panta arm having two arms connected in an X-shape between a table and a base, and elevating and lowering the table. The present invention relates to a moving table lift device.

[0002]

2. Description of the Related Art Conventionally, in this type of table lift apparatus, a hydraulic cylinder is used in most cases as a drive source for extending and retracting a pant arm, for example, as disclosed in Japanese Patent Publication No. 59-41920. However, in this case, there is a problem that the smell of oil is dissipated particularly around the hydraulic pump, and dust adheres to the evaporation point of the oil, making maintenance troublesome. In some fields, it was necessary to take sufficient measures to address this problem. Further, if an oil leak occurs, the table naturally falls, and it is necessary to take sufficient measures against this trouble.
Therefore, conventionally, as a drive source without such a problem, for example, a drive source using an electric cylinder as a drive source as shown in FIGS. 7 and 8 has been provided.

[0003] A table lift device 20 shown in FIG.
a and 22a are formed facing each other, and both cam portions 21a and 22a are formed.
By moving the follower 23 along the space, the arms 21 and 22 are rotated relative to each other to expand and contract the panta arm, and the movement of the follower 23 is performed by the electric cylinder 10. Also,
The table lift device 30 shown in FIG. 8 has a structure in which a link mechanism 33 is interposed between the two arms 31 and 32 of the panta arm, and the link mechanism 33 is operated to expand and contract by the electric cylinder 10 to expand and contract the panta arm. Was.

[0004] Here, the electric cylinder 10 which is usually commercially available mainly comprises a ball screw. Specifically, as shown in FIG. 6, an electric motor 10a and a reduction gear 10b are provided.
, The screw shaft 10d rotatably supported by the screw shaft support portion 10c is rotated to thereby reciprocate the nut 10e.
Rod 11a. In the electric cylinder 10 having such a configuration, it is advantageous to use the electric cylinder 10 in a direction of receiving a load (lifting the table) on a pulling side of the nut 10e (a direction approaching the screw shaft supporting portion 10c). Because if the load is applied on the pulling side of the nut 10e, it is not necessary to consider the strength against buckling of the screw shaft 10d,
This is because the screw shaft 10d need only have a smaller screw diameter, which is advantageous for cost reduction or downsizing of the apparatus. In this regard, both the table lifts 20, 30 exemplified above both pull the nut 10e toward the pulling side. The electric cylinder 10 is used in such a direction that the panta arm extends (the table rises) when moved.

[0005]

However, due to its structure, the electric cylinder 10 has substantially the same stroke S (S10).
= S11), the overall length L is longer than that of the normal hydraulic cylinder 11 (L10> L11), so that it is difficult to make the table lift device compact, and in particular, the conventional table lift device 20 , 30, as shown in the figure, since the electric cylinder 10 is arranged in a substantially half area on the left side of the panta arm, the rear portion protrudes to the side and cannot be efficiently arranged. However, there was a problem that the size became large.

Therefore, as an example in which the pulling side of the nut 10e is used for raising the table while avoiding an increase in the size of the apparatus, for example, a table lift apparatus 40 as shown in FIG. 9 can be considered. The table lift device 40 includes the electric cylinder 1
0 is a connecting fulcrum 43 between the outer arm 41 and the inner arm 42.
The upper and lower sides (shown on the lower side in the figure) are arranged between both arms 41 and 42 so that the electric cylinder 10 protrudes to the side of the panta arm. There is no need to increase the size of the apparatus. However, according to this configuration, the thrust (hereinafter, also referred to as "necessary thrust") of the electric cylinder 10 required for raising the table greatly differs between near the lower end of the table and near the upper end. There is a problem that thrust is not used effectively.

More specifically, FIG. 9A shows a panta arm near the lower end of the table, and FIG. 9B shows a panta arm near the upper end of the table. In any case, the required thrust F is F = L × W / h. L (L1, L2) is a horizontal distance between the connection fulcrum 43 and the roller fulcrum 44 of the panta arm, W is the weight of the table 45 (including the load weight),
h (h1, h2) is the vertical distance between the connection point 43 and the electric cylinder 10. Therefore, the thrust F is set near the table lower end (FIG. 9A) and near the table upper end (FIG. 9A).
(B)), L1> L2 and h1 <h
Since F2, F1> F2, and the required thrust is less near the rising end of the table. From this,
Since the thrust of the electric cylinder 10 is set based on the necessary thrust near the lower end of the table, the thrust of the electric cylinder 10 is not efficiently used near the upper end of the table.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problem when an electric cylinder is used as a drive source. An object of the present invention is to provide a table lift device in which a difference in thrust is small, and therefore, the thrust of an electric cylinder is effectively used.

[0009]

According to the first aspect of the present invention, a punter arm having an X-shaped outer arm and an inner arm connected between a table and a base is provided. A table lift device for raising and lowering a table by extending and retracting a pant arm, wherein one end is rotatably connected to the inner arm between the outer arm and the inner arm, and the other end is connected to the outer arm. An intermediate arm that is rotatably connected to be displaceable along the arm longitudinal direction and extends the punter arm when the other end is displaced toward the center in the arm longitudinal direction; and the intermediate arm and the outer arm An electric cylinder is interposed between the intermediate arm and the other end, and the other end of the intermediate arm is displaced toward the center in the arm longitudinal direction by an operation of the electric cylinder on a nut pulling side.

[0010]

According to the first aspect of the present invention, when the electric cylinder is operated toward the nut pulling side, the other end of the intermediate arm is displaced toward the center of the arm to extend the punter arm, thereby raising the table. On the other hand, when the electric cylinder is actuated to the nut pushing side, the other end of the intermediate arm is displaced in a direction away from the arm center to contract the panta arm, whereby the table is lowered. As described above, since the table is raised by the operation of the nut pulling side, the table load is applied to the screw shaft of the electric cylinder at this time. Therefore,
This table load is not applied as a buckling load to the screw shaft of the electric cylinder, so that it is not necessary to consider the buckling strength of the screw shaft when the table is raised, and thus the screw shaft diameter is smaller and smaller. Can be used as a drive source, and the size of the table lift device can be reduced.

Further, since the electric cylinder is interposed between the intermediate arm and the outer arm, the rear portion thereof can be arranged compactly without protruding from the punter arm to the side as in the prior art, so that the size of the device is increased. Will not be invited.

Further, the electric cylinder is interposed between the outer arm and the intermediate arm, and the other end of the intermediate arm is connected to the outer arm so as to be displaceable along its longitudinal direction. Regardless of the operating state, it can be arranged in a state where it is not displaced from a position along the outer arm,
Thus, the positional relationship between the electric cylinder and the outer arm can be maintained substantially constant. According to this, the thrust (necessary thrust) of the electric cylinder required for raising the table near the lower end of the table and the vicinity of the upper end is not greatly different from that of the related art. Regardless, it is used efficiently.

[0013]

According to the first aspect of the present invention, the difference between the required thrust near the lower end of the table and the vicinity of the upper end can be reduced while the electric cylinder is compactly arranged without protruding to the side. The thrust of the electric cylinder can be effectively used without increasing the size of the device.

[0014]

Next, an embodiment of the present invention will be described with reference to FIGS. The table lift device 1 of the present example has two sets of panta arms 4, 4 interposed between the table 2 and the base 3, and expands and contracts both the panta arms 4, 4 in the up-down direction. The two punter arms 4 and 4 are configured such that the outer arm 5 and the inner arm 6 are rotatably connected to each other in an X-shape via a connection fulcrum 7 substantially at the center in the longitudinal direction. Have been
This is the same as the conventional table lift device.

The left end of the outer arm 5 in the figure is
a is rotatably supported on the upper surface of the base 3 through the base 2a, and the left end of the inner arm 6 in the figure is fixed via the fixed fulcrum 6a.
Is rotatably supported by the lower surface of the. The right end of the outer arm 5 in the figure is connected to the table 2 via a roller fulcrum 5b.
The right end of the inner arm 6 in the figure is movably supported along the upper surface of the base 3 via a roller fulcrum 6b.

As shown in FIG. 2, a connecting rod 8 is fixedly bridged between the outer arms 5, 5 of the two panta arms 4, 4, near the fixed fulcrum 5a. A connecting flange 8a is provided at the center of the connecting rod 8, and the rear end of the electric cylinder 10 as a drive source of the table lift device 1 of this embodiment can rotate through a fulcrum 8b on the connecting flange 8a. It is connected to. A commercially available electric cylinder 10 is generally used and does not require any particular change in practicing the present invention. Therefore, the same reference numerals as those described above are used in the following description.

Next, the connecting fulcrum 7 of the inner arms 6, 6
The fulcrum 9 is closer to the roller fulcrum 6b.
The intermediate arm 9 is rotatably supported via a.
As shown in FIG. 2, a connecting rod 12 is supported between the ends of the two intermediate arms 9 and 9. Both ends of the connecting rod 12 protrude from the intermediate arm 9 toward the outer arm 5, and guide rollers 13 are rotatably supported on the protruding portions.

On the other hand, the connecting fulcrum 7 of the outer arms 5, 5
On the tip side (on the side of the roller fulcrum 5b), guide grooves 14 longer along the longitudinal direction are formed. The guide rollers 13 are slidably supported in the two guide grooves 14, respectively, whereby the tips of the intermediate arms 9, 9 are connected to the outer arm 5. For this reason, with the rotation of the outer arm 5 and the inner arm 6 due to the expansion and contraction of the panta arm 4, the intermediate arm 9
and the guide roller 13 moves in the guide groove 14.

The tip of a nut 10e of the electric cylinder 10 is rotatably connected to the center of the connecting rod 12.

According to the table lift device 1 of the present embodiment configured as described above, the following operation is performed. When the electric cylinder 10 is actuated on the pulling side of the nut 10e (in the direction in which the nut 10e approaches the screw shaft support 10c) in a state where the table 2 is located near the lower end as shown in FIG. Guide rollers 13, 13 are guide grooves 1
4, the intermediate arms 9, 9 are rotated in the rising direction (counterclockwise direction in the drawing), whereby the outer arm 5 is rotated in the rising direction, and the inner arm 6 is rotated. It rotates in the rising direction (clockwise direction in the figure), so that the two panta arms 4, 4 are extended upward, and the table 2 is raised.

On the other hand, when the table 2 is located near the rising end as shown in FIG.
Is actuated on the pushing side of the nut 10e, the guide roller 13 moves in the guide groove 14 toward the arm tip side, so that the intermediate arm 9 is rotated in the falling direction, whereby the outer arm 5 falls. , And the inner arm 6 rotates in the falling direction, so that the two panta arms 4, 4 are contracted downward, and the table 2 is lowered.

As described above, the electric cylinder 10 is connected to the nut 1
Table 2 rises when operated to the pull side of 0e,
The table 2 moves down when the nut 10e is operated to the pushing side. Therefore, since the electric cylinder 10 is used in a direction to receive a load on the pulling side of the nut 10e,
The buckling strength of the screw shaft 10d is advantageous, and the table 2 can be raised and lowered by the small electric cylinder 10 having a relatively small diameter of the screw shaft 10d.

Further, the electric cylinder 10 is not arranged in the left and right side with respect to the connection fulcrum 7 of the panta arm 4 as in the prior art, but is arranged substantially at the center of the panta arm 4 in the left and right direction. Therefore, the rear portion does not protrude to the side, so that the size of the table lift device 1 does not increase.

Further, the electric cylinder 10 is interposed indirectly between the outer arm 5 and the inner arm 6 via the intermediate arm 9, and as shown in FIG. It is not designed to be directly interposed. That is, the intermediate arm 9 is rotated by the operation of the electric cylinder 10, and the fulcrum, that is, the position of the guide roller 13 is displaced to expand and contract the panta arm 4.

Here, consider how this thrust acts on each of the arms 5 and 6 when the intermediate arm 9 is rotated in the rising direction by the thrust F on the pulling side of the electric cylinder 10. As shown in FIG. 4, the thrust F of the electric cylinder 10 causes the arm 5 to have a moment M in the rising direction.
1 = F × c (c is the torque radius) acts. Further, since the intermediate arm 9 is rotated in the rising direction, a moment M2 = (d / b) × F × a in the rising direction acts on the arm 5 via the guide roller 13. Further, when the intermediate arm 9 is rotated in the rising direction, a force in the pushing direction acts on the fulcrum 9a, whereby the moment M3 = (F
/ Cos θ) × R acts. These three rotational moments M1, M2, M3 are used in the rising direction of the arms 5, 6, that is, in the rising direction of the table 2. On the other hand, a load W acts on the table 2 and acts on both arms 5 and 6 in the falling direction as a total moment M = 2WU.

Therefore, when the table 2 rises, M = M
1 + M2 + M3, that is, 2WU = F × c + (d / b) × F × a + (F / cos
θ) × R, and F = (2bWU · cos θ) / (bc · cos θ + ad
Cos θ + Rb) is obtained. Therefore, as shown in FIG. 5, when the numerical values of each part in the actual machine manufactured by the present applicant are applied to the above equation, the required thrust F of the electric cylinder 10 is about 5774 kg near the lower end of the table 2 and increases. The required thrust of the electric cylinder 10 is almost the same near the lower end and near the upper end of the table 2 according to the table left apparatus 1 of the present example, which is substantially different from the conventional one. It was proved that there was no such thing.

As described above, the difference between the required thrust F near the lower end and the vicinity of the upper end of the table 2 can be considered to be substantially the same, and there is no great difference unlike the conventional case. Is effectively used, and the electric cylinder 10 and, consequently, the table lift device can be downsized.

In the above description, the table 2 and the base 3
The table lift device 1 in which a pair of left and right punter arms 4 and 4 is arranged between the two is illustrated, but the present invention is applied to a so-called multi-stage punter arm type table lift device in which the punter arms 4 are connected in a plurality of upper and lower stages. It goes without saying that it is possible.

[Brief description of the drawings]

FIG. 1 is a front view of a table lift device near a table rising end according to an embodiment of the present invention.

FIG. 2 is a plan view of the table lift device.

FIG. 3 is a front view of the table lift device near a table lower end;

FIG. 4 is an explanatory diagram showing moments acting on both arms when the table is raised.

FIG. 5 is a view showing actual dimensions of each part in the table lift device.

FIG. 6 is a diagram showing a comparison of the total lengths of an electric cylinder and a hydraulic cylinder.

FIG. 7 is a front view of a table lift using a conventional electric cylinder as a driving source.

FIG. 8 is a front view of another embodiment of a table lift using a conventional electric cylinder as a drive source.

9A and 9B are diagrams showing displacement of each part of the conventional table lift device, wherein FIG. 9A shows a time when the table is lowered, and FIG. 9B shows a time when the table is raised.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Table lift device 2 ... Table, 3 ... Base 4 ... Panta arm 5 ... Outer arm, 5a ... Fixed fulcrum, 5b ... Roller fulcrum 6 ... Inner arm, 6a ... Fixed fulcrum, 6b ... Roller fulcrum 7 ... Connection fulcrum 8 ... connecting rod, 8a ... connecting flange, 8b ... fulcrum 9 ... intermediate arm, 9a ... fulcrum 12 ... connecting rod 13 ... guide roller 14 ... guide groove 10 ... electric cylinder, 10d ... screw shaft, 10e ... nut 20 ... conventional Electric cylinder type table lift (cam type) 30 ... Conventional electric cylinder type table lift (link type) 40 ... Electric cylinder type table lift device (compact type)

Claims (1)

(57) [Claims] 1. A table lift that interposes a panta arm between an outer arm and an inner arm in an X-shape between a table and a base and moves the table up and down by expanding and contracting the panta arm. An apparatus, wherein one end is rotatably connected to the inner arm between the outer arm and the inner arm, and the other end is rotatably connected to the outer arm and displaceable along the arm longitudinal direction. An intermediate arm for extending the panta arm when the other end is displaced toward the center in the arm longitudinal direction, an electric cylinder interposed between the intermediate arm and the outer arm, A table lift apparatus wherein the other end of the intermediate arm is displaced toward the center in the longitudinal direction of the arm by an operation on a nut pulling side.