KR100345180B1 - Connecting structure for coupling a pully to a spindle in a main shaft unit of automatic lathe - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle and pulley connection structure in an automatic lathe spindle, and in particular, a connection structure in which the spindle and pulley can be coupled without using a key.

In the spindle and pulley connection structure of the automatic lathe spindle of the present invention, a threaded portion 52 is provided at an outer diameter portion of the spindle 50, and a bearing nut for supporting the end plate 24 at the threaded portion 52 thereof ( 20 is fastened, a pilot shaft portion 54 having a predetermined diameter is formed at an end portion of the spindle 50 extending from the screw portion 52, and the boss portion 72 of the pulley 70 is A pilot hole portion 74 having a predetermined depth is formed corresponding to the pilot shaft portion 54 of the spindle 50 so that the outer diameter of the pilot shaft portion 54 and the inner diameter of the pilot hole portion 74 are fitted and fitted. An end surface 56 of the pilot shaft portion 54 is tightly coupled to the inner bottom surface 76 of the pilot hole portion 74, and the end surface 56 of the spindle 50 and the spindle 50 in close contact with each other. And the inner bottom surface 76 as a plurality of bolts 90 from the outer end surface of the pulley 70. It is characterized in that the fastening is fixed in the axial direction.

The present invention improves the rotational stability of the spindle by eliminating the gap between the spindle and the pulley assembly, thereby realizing high speed and high precision of the lathe, and improving the rigidity and disassembling and assembling of the spindle.

Description

Connecting structure for coupling a pully to a spindle in a main shaft unit of automatic lathe}

The present invention relates to a spindle and pulley connection structure in the spindle of the automatic lathe, and more particularly, by adopting a connection method of the cross-sectional fastening structure without the use of a key (key) to remove the gap between the spindle and the pulley assembly to rotate the spindle The present invention relates to a spindle and pulley connection structure in the spindle of an automatic lathe, which is capable of achieving high speed and high precision of the lathe by improving stability, and improving the rigidity of the spindle and facilitating disassembly and assembly.

As you know, automatic lathes such as NC lathes, CNC lathes, and machining centers perform rotary cutting operations while automatically controlling servo mechanisms consisting mainly of a spindle (center) and tool post (tool post) by a control system. .

The main shaft of the automatic lathe is equipped with a chuck on the rotating spindle by receiving power from the motor, and the cutting work is performed while rotating the workpiece by setting the workpiece on the chuck thereof. This will have the greatest impact on precision.

Here, the rotational stability of the spindle is determined not only by the precision of the spindle itself, but also by the bearing support method and the connection state between the pulley and the spindle for receiving power from the motor. In recent years, the development of the technology has maintained a very stable technology, the spindle rotational stability is actually determined by the connection structure of the pulley and the spindle.

1A and 1B illustrate an example of a spindle structure of an automatic lathe for explaining a connection structure of a conventional pulley and a spindle, the spindle 10 forming a rotating part of the spindle 2 is one side of the body of the shelf. It is rotatably supported by a plurality of bearings (14a, 14b, 14c) to the headstock 12 is fixed to, the pulley 16 is coupled to the lower end of the spindle 10, based on Figure 1a, the pulley 16 is connected to the pulley and the belt (not shown) of the motor (not shown) provided on the other side of the shelf body to receive the power from the motor to rotate the spindle 10. On the basis of the state shown in the figure is mounted on the upper end of the spindle 10 the chuck for setting the workpiece.

Here, when looking at the coupling relationship between the spindle 10 and the pulley 16 in detail, the key groove (10a, 16a) corresponding to each other in the outer diameter of the spindle 10 and the inner diameter of the boss portion of the pulley (16) is provided Then, the key 18 is inserted into the key grooves 10a and 16a thereof, and then the bearing nut 20 is fastened to the spindle 10 at the end of the boss portion of the pulley 16 to be fixed. The bearing nut 20 is in close contact with the pulley 16 toward the bearing 14b, and the inner end plate 24 connected to the spindle 10 by the key 22 on the other side of the pulley 16 of the bearing 14b. It comes in close contact with the inner ring. The outer ring of the bearing 14b is supported by an outer end plate 26 which is fastened to the headstock 12 as shown.

In the conventional spindle and pulley connection structure as described above, in order to smoothly assemble the spindle and the pulley, the gap between the outer diameter of the spindle and the inner diameter of the boss of the pulley is generally maintained at 0.005 mm to 0.015 mm, and the spindle and the pulley are rotated. If the pulley is moved by the gap in the radial direction every one rotation due to the belt tension is repeatedly generated. As a result, vibrations and noises are generated on the spindle, and excessive loads are added to the bearings and parts, which in turn adversely affects the accuracy, lifespan, and rigidity of the spindle, and in particular, lowers the machining accuracy of the workpiece. There is a problem that can not achieve a high speed of the spindle for.

In order to solve these problems, the gap between the roundness and the cylindricalness of pulleys must be reduced to reduce the gaps. Therefore, realistic difficulties are encountered in processing. In case of changing the gap and eliminating gaps and maintaining the fastening, it is necessary to simultaneously adjust the height until the key is fitted. Will occur.

Figure 2 shows another conventional example, which tapered the coupling portion of the spindle 10 and the pulley 16 to eliminate the gap between the spindle 10 and the pulley 16 generated in the previous example. The structure bonded together is shown.

That is, the ring distance 28 is formed between the boss end of the pulley 16 and the inner end plate 24 while the outer diameter of the spindle 10 and the boss inner diameter of the pulley 16 are formed by the taper portion TP. In order to adjust the coupling degree of the taper portion TP of the spindle 20 and the pulley 16 while adjusting the thickness of the ring distance 28 by grinding or the like during assembly. It is a combination method.

In the case of adopting the above coupling method, the gap between the spindle and the pulley can be removed by taper, but the cost increases in the taper process, and the thickness of the ring distance 28 is finely adjusted several times. Since it is necessary to assemble, there is a problem that a lot of time and effort should be put into the assembly.

Moreover, the tapered portion machining deviation of each spindle and each pulley always changes the position at which the pulley is engaged, that is, the axial fixed position of the pulley. Correspondingly, since the position of the pulley on the motor side connected to the pulley and the belt must also be changed, there is a burden that a separate device for adjusting the pulley position on the motor side is required.

In addition, the problem common to the two conventional examples is that both examples are the key fixing method, so that the stress is concentrated in the key groove so that the rigidity of the spindle is lowered. Bars should be mounted symmetrically, which causes the rotational balance to be misaligned due to the deviation of the symmetry of the keys, and naturally the backlash (gap) exists between the keyway of the spindle and pulley and the side of the key. If repeatedly performed, movement in the rotational direction occurs as much as the backlash, causing vibration and noise.

Furthermore, in consideration of the rigidity caused by the formation of the key groove, the length of the boss portion of the pulley must be increased, thereby increasing the inner diameter grinding cost of the boss portion and increasing the weight moment of inertia of the pulley, which adversely affects the stable rotation of the spindle.

The present invention has been made to solve the above problems, by eliminating the gap between the spindle and the pulley assembly by adopting the connection method of the cross-sectional fastening structure without the use of the key and the connection method that can be forcefully fitted between the spindle and the pulley. In this way, the rotational stability of the spindle can be improved to achieve high speed and high precision of the lathe, and the spindle and pulley connection structure in the spindle of the automatic lathe, which improves the rigidity of the spindle and is also advantageous for disassembly and assembly, is aimed at. have.

In order to achieve this object, the spindle and pulley connection structure in the spindle of the lathe according to the present invention is provided with a threaded portion at the outer diameter of the spindle, and a bearing nut for supporting the end plate is fastened to the threaded portion thereof, and from the screwed portion. The pilot shaft portion having a predetermined diameter is formed at an end portion of the extended spindle, and the boss portion of the pulley is formed with a pilot hole portion having a predetermined depth corresponding to the pilot shaft portion of the spindle. While the inner diameter of the hole is combined with the fitting, the end face of the pilot shaft portion is tightly coupled to the inner bottom of the pilot hole, and the closely contacted spindle and the end face and the inner bottom of the spindle are formed from a plurality of outer end faces of the pulley. Fastening in the axial direction by bolts.

1A and 1B show an example of a conventional spindle and pulley connection structure, FIG. 1A is a sectional view of the main shaft, and FIG. 1B is an A-A cross-sectional view of FIG. 1A.

Figure 2 shows a further connection structure of a conventional spindle and pulley, an enlarged cross-sectional view showing only the connecting portion of the pulley according to Figure 1a.

Figure 3a to 3c shows the connection structure of the spindle and the pulley according to the present invention, Figure 3a is a main shaft cross-sectional view and a bottom view from above, Figure 3b is an enlarged cross-sectional view of the main portion, Figure 3c is an enlarged cross-sectional view of the main portion coupling

<Explanation of symbols for the main parts of the drawings>

12: headstock 14a, 14b, 14c: bearing

18,22: Height 20: Bearing nut

24: inner end plate 26: outer end plate

50: spindle 52: thread

54: pilot shaft portion 56: end face

70: pulley 72: boss

74: pilot hole 76: inner bottom

90: bolt

Hereinafter, with reference to the accompanying drawings illustrating a preferred embodiment of the present invention in more detail.

Figure 3a to 3c shows the connection structure of the spindle and the pulley according to the present invention, Figure 3a is a main shaft cross-sectional view and a bottom view from top to bottom, Figure 3b is an enlarged cross-sectional view of the main portion, Figure 3c is enlarged main assembly It is a cross section.

The same parts as those in Figs. 1 and 2 are given the same reference numerals, and repeated description thereof will be omitted.

First, as shown in Figure 3a, the connecting structure of the spindle 50 and the pulley 70 in the main shaft 100 according to the present invention, the spindle (from the bearing 14b for supporting the rear end of the spindle 50) 50) The outer and inner end plates 26, 24, bearing nuts 20, and pulleys 70 are sequentially arranged on the end side, and the outer and inner end plates 26 supporting the side ends of the bearings 14b. , The bearing nut 20 directly supports the pulley 70 at the end of the spindle 50 while the bearing nut 20 directly supports the end surface of the spindle 50 and the cross section of the pulley 70 by a plurality of bolts 90. It is a structure fastened in the direction.

Next, FIGS. 3B and 3C show the above-described connection structure in more detail. A thread portion 52 is provided at an outer diameter portion of the spindle 50 extending from the end plate 24, and the thread portion 52 thereof. ), The bearing nut 20 is fastened to closely support the end plate 24 toward the bearing 14b.

In addition, a pilot shaft portion 54 having a predetermined diameter is formed at an end portion of the spindle 50 extending from the screw portion 52, and the boss portion 72 of the pulley 70 has the spindle ( The pilot hole portion 74 corresponding to the pilot shaft portion 54 of the 50 is formed to a depth shorter than the length of the pilot shaft portion 54, so that the outer diameter of the pilot shaft portion 54 and the inner diameter of the pilot hole portion 74 are Engaged in a fit to hold some fastening, the end face 56 of the pilot shaft portion 54 is in close contact with the inner bottom surface 76 of the pilot hole 74.

In addition, the end surface 56 of the spindle 50 has a plurality of tap holes 58 formed at equal intervals (equivalent) in the axial direction, and the pulley 70 has a plurality of fastenings corresponding to the tap holes 58 thereof. A ball 78 is formed, and a bolt 90 having a threaded portion 92 and a shank portion 94 is provided corresponding to the tab hole 58 and the fastening hole 78, so that the spindle 50 as described above. The bolt 90 is passed through the fastening hole 78 of the pulley 70 in a state where the pulley 70 is fitted to the pulley 70, and fastened to the tab hole 58 of the spindle 50.

Here, the length of the pilot shaft portion 54, in particular the pilot hole portion 74, it is desirable to keep the coupling concentricity of the pulley 70 and the spindle 50 as short as possible within the range that can be maintained within the design range. By keeping the fitting length short, separation and coupling of the pulleys are facilitated, and accordingly, there is no difficulty in separation and coupling even if the fastening is maintained even when the pilot shaft portion 54 and the pilot hole portion 74 are fitted. The gap at the fitting can be removed. The fastening at the time of fitting the pilot shaft portion 54 and the pilot hole portion 74 should be set so that the separation and coupling of the pulley 70 will not be unreasonable as described above, while maintaining uniform and precise quality for each produced article. It should be set within the range that is possible, preferably the fastener within 0.007mm (in other words, the inner diameter of the pilot hole portion 74 minus the outer diameter of the pilot shaft portion 54 is -0.007mm to 0.000mm, or The value obtained by subtracting the inner diameter of the pilot hole portion 74 from the outer diameter of the pilot shaft portion 54 is 0.000 to 0.007 mm), and more preferably, a clamp of 0.003 mm.

In the present invention, it is possible to maintain a narrow range of fasteners as described above, and as a result, the workability of this part is greatly improved since the fitting length of the pilot shaft portion 54 and the pilot hole portion 74 can be kept short. This is because the cylindricality and roundness of the pilot hole portion 74 of the pulley 70 can be precisely maintained. As you know, the grinding wheel's diameter is much smaller than the diameter of the machined part and the grinding wheel's wear is severe because the grinding wheel is rotated at a high speed. In the present invention, in view of the difficulty of grinding the inner diameter, it proposes a connection structure that can minimize the length of the pilot hole (74).

On the other hand, in the present invention as described above, when power is transmitted from the motor to the pulley 70 when performing the cutting operation, the rotational force of the pulley 70 is the end surface of the spindle (50) by the bolt (90) fastening 56 is transmitted to the spindle 50 by the contact friction force between the inner bottom surface 76 of the pulley 70 and the shear force of the bolt 90 to rotate the spindle 50.

The spindle and pulley connection structure in the automatic lathe spindle according to the present invention excludes the conventional key coupling method, and the pilot shaft portion 54 of the spindle 50 and the pilot hole portion 74 of the pulley 70 maintain the fastening. In addition, the end surface 56 of the spindle 50 and the inner bottom surface 76 of the pulley 70 are tightly coupled by the bolt 90, and the spindle 50 and the pulley ( 70) As the clearance of the assembly part is removed, vibration and noise during rotation can be significantly reduced, and accordingly, rotational stability (rotation balance) of the main shaft is improved.

In addition, the outer diameter of the pilot shaft portion 54 of the spindle 50 and the inner diameter of the pilot hole 74 of the pulley 70 are structures used only for the purpose of maintaining concentricity at the time of assembly regardless of power transmission. The fit length can be kept short so that the workability of this part is improved. Therefore, the cylinder diameter and concentricity of the pilot shaft portion 54 of the spindle 50 and especially the inner diameter of the pilot hole portion 74 of the pulley 74 can be precisely maintained, so that the fitting portion can be precisely held in a narrow range of fastenings. Can be.

In addition, as a keyless connection structure, no keyway processing is required on the spindle 50 and the pulley 70, and the additional finishing of the key during assembly as in the conventional example shown in FIG. It is not necessary to further refine the ring distance as in the example of the present invention, and improve the rigidity of the spindle 50 by preventing stress concentration caused by the key groove, and there is no backlash problem between the key and the key groove. It can maintain stable rotation.

Furthermore, since the end surface 54 and the inner bottom surface 74 are closely assembled when the spindle 50 and the pulley 70 are coupled, the coupling position of the pulley 70 is always constant, which is shown in FIG. 2. As in the conventional example, there is no need to adjust the position of the pulley on the motor side separately, and it is easy to assemble and separate even if the spindle 50 and the pulley 70 are forcibly fitted because of the structure that can shorten the length of the fitting portion. .

The present invention provides the convenience of reduction and maintenance of the production cost of the spindle according to the advantages as described above, in particular, it is advantageous for the high speed and high precision of the spindle according to the improved rotational stability of the spindle, and ultimately, cutting precision in the automatic lathe It can be improved.

Claims (2)

Spindle 50 which is rotatably supported by a plurality of bearings inside the headstock 12 fixed to one side of the automatic lathe, and a motor provided on another side of the shelf body by being coupled to the spindle 10 end thereof In the main shaft of the automatic lathe comprising a pulley 70 connected to the side pulley and the belt, A threaded portion 52 is provided at an outer diameter portion of the spindle 50 extending from an end plate 24 supporting a side end of a bearing proximate to the pulley 60 among the bearings, and the end plate The bearing nut 20 for supporting 24 is fastened, A pilot shaft portion 54 having a predetermined diameter is formed at an end portion of the spindle 50 extending from the thread portion 52, and the boss portion 72 of the pulley 70 is a pilot of the spindle 50. The pilot hole portion 74 having a predetermined depth is formed corresponding to the shaft portion 54 so that the outer diameter of the pilot shaft portion 54 and the inner diameter of the pilot hole portion 74 are fitted to each other and the pilot shaft portion 54 is fitted. The end face 56 of is in close contact with the inner bottom surface 76 of the pilot hole portion 74, The spindle 50 and the end surface 56 and the inner bottom surface 76 of the spindle 50 which are in close contact with each other are fastened axially by a plurality of bolts 90 from the outer end surface of the pulley 70. Spindle and pulley connection structure in the spindle of the automatic lathe. The method according to claim 1, The fitting between the outer diameter of the pilot shaft portion 54 of the spindle 50 and the inner diameter of the pilot hole 74 of the pulley 70 maintains a fastener within 0.007 mm. rescue.