KR20100064427A - Tool unclamping shock absorbing device for main spindle of machine tool - Google Patents

Abstract

PURPOSE: A shock absorbing device in unclamping a tool of a main spindle of a machine tool is provided to improve stability in high speed rotation by improving the natural frequency of a spindle by reducing spindle length and mass. CONSTITUTION: A shock absorbing device in unclamping a tool of a main spindle of a machine tool comprises a draw bar(20), a draw bar spring(30), a draw bar cylinder(40), a ring(50), and a buffer spring(60). The draw bar spring keeps backward motion of a draw bar during clamping a tool. The draw bar cylinder comprises a cylinder body(41) and a cylinder rod(42). The cylinder rod moves forward during unclamping the tool and contacts the draw bar. The cylinder rod pushes forward the draw bar with power which is higher than the force of restitution of the draw bar spring. The cylinder rod moves backward during clamping the tool and is separated from the draw bar. The ring moves forward and backward in the same direction with the cylinder body.

Description

Tool unclamping shock absorbing device for main spindle of machine tool}

The present invention relates to a structure of a high speed spindle for a machining center, and more particularly, to the mass of the spindle rotating body for mitigating the impact on the bearing during the tool clamp unclamping of the machining center spindle and for stable operation at high speed. It relates to a structure that enables length reduction.

In the case of the high speed spindle of the machining center, the tool is clamped and unclamped at the end of the spindle spindle 1 (left side of the drawing), as shown in FIG. 1, and drawn inside the spindle 1 for tool clamping / unclamping. Bar 2 is provided. And a drawbar cylinder (4) consisting of a cylinder body (4-1) and a cylinder rod (4-2) is provided for forward and backward transfer of the drawbar (2), to supply the required hydraulic pressure to the drawbar cylinder (4) For this purpose, a hydraulic pressure supply unit 7 composed of hydraulic ports 7-1 and 7-2 is formed. In addition, a drawbar spring 3 is provided between the drawbar 2 and the spindle spindle 1, and a spindle support bearing 1-1 is provided to support the spindle spindle 1.

Tool unclamping with the drawbar 2 is performed as follows.

First, during the clamping of the tool, the drawbar spring 3 installed between the drawbar 2 and the spindle spindle 1 strongly pulls the tool and the drawbar 2 maintains the reverse (right side of the drawing). As the drawbar cylinder 4 moves backward, a gap is provided between the rear end of the drawbar 2 and the cylinder rod 4-2 so that the drawbar 2 is rotatable.

On the other hand, during tool unclamping, hydraulic pressure is supplied to the drawbar cylinder 4 through the hydraulic supply unit 7 to advance the cylinder rod 4-2 (left side of the drawing), and as a result, the cylinder rod 4-2. Slide the guide bar (2) forward to allow the tool to be released.

As described above, during the tool unclamping, the force is transmitted from the moment when the cylinder rod 4-2 contacts the rear end of the draw bar 2 to push the draw bar 2 forward. The drawbar 2 will move forward only by pushing the drawbar 2 with a force greater than that of 3).

However, in this process, since the force transmitted from the cylinder rod 4-2 to the drawbar 2 is very large, a large impact is transmitted to the spindle support bearing 1-1. In general, since the tool clamp and the unclamp operation is frequently performed during the operation of the machine tool, if a shock such as an abnormality is frequently transmitted to the spindle support bearing 1-1, the probability of breakage due to a decrease in the life of the bearing increases.

In order to alleviate such problems, that is, the impact during tool unclamping of a high speed spindle, the following structure has been used.

That is, as shown in Figure 1, the spring (9) is installed in the bracket (8) supporting the rear end of the drawbar cylinder (4), the lock nut (5) is provided at the end of the drawbar (2) At the same time, a hook 6 was installed at a position adjacent to the cylinder body 4-1 so that the hook 6 was caught by the lock nut 5 and the cylinder body 4-2, respectively.

Due to this structure, the cylinder body 4-1 is retracted by the reaction force when the cylinder rod 4-2 moves forward (left side of the drawing) and contacts the drawbar 2 during unclamping, and the hook 6 rotates the spindle spindle. It is caught by the lock nut 5 fixed to (1). In this state, if the cylinder rod 4-2 continues to push the drawbar 2 forward, the cylinder body 4-1 is connected to the spindle spindle 1, so only the cylinder rod 4-2 is internal. In the state where the draw bar (2) is pushed in, the force is not transmitted to the spindle support bearing (1-1).

However, the conventional shock absorber has the following problems.

First, the outer diameter and the length of the lock nut 5 become long.

That is, the outer diameter of the lock nut 5 connecting the spindle 1 and the hook 6 in order to hook the spindle spindle (1) to the hook (6) hanging on the cylinder body (4-1) when unclamping The hook 6 should be enlarged to correspond to the outer diameter.

In addition, when the cylinder rod 4-2 pushes the drawbar 2 forward after the hook 6 is caught by the lock nut 5, a reaction force is generated to the lock nut 5 to the rear. In order to increase the tightening force between the lock nut 5 and the lock nut 5, the length of the threaded portion for coupling between the lock nut 5 and the main shaft 1 is required. Therefore, the length of the lock nut 5 is required. Will be longer.

For this reason, the distance from the spindle support bearing (1-1) to the drawbar cylinder (4) becomes long, which leads to a decrease in the dynamic characteristics (stiffness) of the spindle. And the mass of the spindle increases because the length protruding from the spindle support bearing 1-1 increases.

In order to operate the spindle stably at high rotation speed, the first natural frequency of the whole rotor including the spindle should be designed to be much higher than the maximum rotation speed. The natural frequency of the spindle is inversely proportional to the weight of the rotor and the spindle support stiffness And the system stiffness, including the spindle's own stiffness. Therefore, the decrease in rigidity of the spindle and the increase in mass result in a decrease in the natural frequency of the rotating body, and thus, it is difficult to secure stability during the high speed rotation of the spindle 1.

Secondly, it is difficult to adjust and assemble the gap between the hook 6 and the lock nut 5, and the hook covers the end of the spindle spindle 1 in the radial direction, which causes difficulty in attaching an additional locator device. In addition, there is a disadvantage that the noise due to the air friction sound is also amplified at high speed by the presence of a complicated shape near the spindle spindle (1).

The present invention is to solve the above problems, the conventional structure for mitigating the impact on the bearing during tool unclamping for high speed rotation in the machining center spindle, that is, by connecting the spindle and the cylinder at the moment of unclamping operation It is a technical problem to solve the above problems that occur when applying a structure that pushes only the drawbar in the spindle.

In addition, the present invention is to ensure the stability of the spindle at high speed by mitigating the impact to the bearing during unclamping to protect the bearing and to reduce the length and mass from the bearing support to the spindle end to increase the natural frequency of the spindle It is a technical task.

In order to achieve the above object, the present invention is a tool unclamping shock absorbing device of the spindle spindle 10 of the machine tool, is inserted into the spindle spindle 10 so as to be moved forward and backward, the spindle spindle 10 when moving forward A drawbar 20 configured to clamp the tool when the spindle unclamps the tool; A drawbar spring (30) installed between the spindle spindle (10) and the drawbar (20) to maintain the reverse state of the drawbar (20) when clamping the tool; A cylinder body 41 and a cylinder rod 42 configured to be able to move back and forth within the cylinder body 41-the cylinder rod 42 is advanced in contact with the drawbar 20 when unclamping the tool. Thereby pushing the drawbar 20 forward with a force greater than the restoring force of the drawbar spring 30, and when the clamping of the tool is reversed, the contact with the drawbar 20 is released. A drawbar cylinder 40 configured; A ring (50) configured to move back and forth in the same direction as the cylinder body (41) inside the cylinder body (41); An impact installed between the ring 50 and the cylinder body 41 to contact the cylinder body 41 and the drawbar 20 when the cylinder body 41 is advanced for unclamping of the tool It includes; a shock absorbing spring (60).

In addition, in the apparatus of the present invention, the hydraulic pressure is introduced when the cylinder rod 42 is moved forward, and the hydraulic pressure is discharged when the cylinder rod 42 is reversed, and the cylinder rod 42 is discharged. The hydraulic supply unit 70 is composed of a second hydraulic port 72, the hydraulic pressure is introduced at the time of the reverse flow and the hydraulic pressure flows out when the cylinder rod 42 is advanced.

In addition, a check valve 80 for adjusting the hydraulic pressure flowing into the second hydraulic port 72; and the second hydraulic port 72 when the cylinder rod 42 advances for unclamping of the tool. Orifice 90 for buffering the hydraulic pressure flowing out to; preferably further comprises.

According to the present invention, the ring 50 and the buffer spring 60 are provided in the drawbar cylinder 40 to alleviate the shock during unclamping to protect the spindle support bearing 11.

In addition, by reducing the spindle length and mass extending rearward from the spindle support bearing 11, the spindle natural frequency is improved to secure stability at high speed.

In addition, when the orifice 90 is additionally installed on the discharge flow path, the fluid discharged to the second hydraulic port 72 escapes during the unclamping, and thus the orifice 90 serves as a resistance, thereby impacting the damping effect. It can absorb more.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

2 shows a tool unclamping impact mitigating device of a machine tool spindle spindle 10 in accordance with one embodiment of the present invention.

As shown, the spindle spindle spindle 10 is supported by a spindle support bearing 11, and the tool is clamped or unclamped at the front end (left side of the figure) of the spindle spindle spindle 10.

The device according to the invention comprises a drawbar 20, a drawbar spring 30, and a drawbar cylinder 40, like the conventional device, in addition to the ring 50 and the buffer spring 60. It is characterized by the installation.

The drawbar 20 is inserted into the spindle spindle spindle 10 so as to be moved forward and backward so that the spindle spindle 10 unclamps the tool when moving forward and the spindle spindle 10 clamps the tool when moving backward. It is composed.

The drawbar spring 30 is installed between the spindle spindle 10 and the drawbar 20 to maintain the tool clamping state by pulling the tool backward when clamping the tool.

The drawbar cylinder 40 is comprised from the cylinder body 41 and the cylinder rod 42 comprised so that forward and backward along the inner peripheral surface of the cylinder body 41 is possible.

The cylinder rod 42 is configured to push forward the drawbar 20 with a force greater than the restoring force of the drawbar spring 30 by advancing and contacting the drawbar 20 during unclamping of the tool. The upper half of the cylinder rod 42 in FIG. 2 shows the cylinder rod 42 advanced for tool unclamping.

In addition, the cylinder rod 42 is reversed when the tool is clamped to release the contact with the draw bar 20, the gap is provided so that the draw bar 20 and the spindle spindle 10 can rotate. The lower half of the cylinder rod 42 of FIG. 2 shows the cylinder rod 42 retracted for tool clamping.

On the other hand, in the apparatus according to the present invention, instead of the conventional lock nut 5 and hook 6 structure in order to alleviate the impact during tool unclamping, the ring 50 and the cushioning spring 60 are inside the drawbar cylinder 40. Laid on.

The ring 50 is installed to be able to move back and forth along the inner circumferential surface of the cylinder body 41 and moves forward and backward in the same direction as the cylinder body 41.

The shock absorbing spring 60 is installed between the ring 50 and the cylinder rod 42 and, as can be seen in the shock absorbing spring 60 shown in the upper half of FIG. 2, the cylinder body 41 for unclamping of the tool. As it moves forward, it is compressed to mitigate the impact of contact with the cylinder body 41 and the drawbar 20.

On the other hand, the hydraulic pressure supply unit 70 is provided for the hydraulic pressure supply for the forward and backward movement of the cylinder rod 42 of the drawbar cylinder (40). The hydraulic pressure supply unit 70 includes a first hydraulic port 71 and a second hydraulic port 72.

In order to advance the cylinder rod 42 for tool unclamping, the hydraulic pressure is supplied to the first hydraulic port 71 and the hydraulic pressure is supplied to the A space inside the cylinder body 41 while the ring 50 moves to the left side and cushions. When the spring 60 is compressed and the shock absorbing spring 60 reaches the compression limit, the cylinder rod 42 in close contact with the shock absorbing spring 60 also moves to the left side (see the upper half of FIG. 2). On the other hand, as the cylinder rod 42 moves forward, the hydraulic pressure existing in the B space is discharged to the second hydraulic port 72.

At this time, the shock transmitted to the drawbar 20 is reduced by the elasticity of the shock absorbing spring 60 until the moment of contacting the cylinder rod 42 on the ring 50. Therefore, the shock absorbed by the shock absorbing spring 60 to make the cylinder rod 42 contact the drawbar 20 more smoothly, thereby alleviating the impact on the spindle support bearing 11 during tool unclamping.

On the contrary, in order to reverse the cylinder rod 42 for the tool clamping, the hydraulic pressure is supplied to the second hydraulic port 72 so that the hydraulic pressure is supplied to the B space inside the cylinder body 41, and the A space is released. The cylinder rod 42 is moved to the right while being discharged to the hydraulic port 73, and the ring 50 is moved to the right while the compressed shock absorbing spring 60 is restored again (see the lower half of FIG. 2).

On the other hand, as shown in Figure 3, according to a preferred embodiment it may be further provided with a check valve 80 and the orifice 90 in the second hydraulic port (72). The rest of the configuration in the embodiment shown in FIG. 3 is the same as in FIG. 2, and description thereof will be omitted.

As shown in FIG. 3, a check valve 80 and an orifice 90 are installed on a flow path connected to the second hydraulic port 72. And the solenoid valve 73 is provided in order to control the direction of the hydraulic pressure transmitted from the hydraulic pressure supply unit 74. As shown in FIG. That is, according to the adjustment of the solenoid 73, the hydraulic pressure flows into the first hydraulic port 71 when the tool is unclamped and flows out to the second hydraulic port 72, and the hydraulic pressure flows into the second hydraulic port 72 when the tool is clamped. 71 is introduced into the first hydraulic port 71 is able to flow out.

The check valve 80 adjusts the hydraulic pressure flowing into the second hydraulic port 72 when the tool is unclamped to a predetermined level.

The orifice 90 acts as a resistance to the hydraulic pressure discharged from the second hydraulic port 72 during the tool unclamping to attenuate the impact, so that the cylinder rod 42 and the ring 60 during the tool clamping It prevents it from moving suddenly.

The operation of the apparatus according to the present invention according to the configuration described above will be described.

tool When unclamping  (Upper half of FIGS. 2 and 3)

When unclamping the tool, the drawbar 20 must be moved forward (left side of the drawing).

To this end, during tool unclamping, the fluid is supplied to the first hydraulic port 71 to increase the pressure in the A space, and the fluid in the B space is discharged through the second hydraulic port 72. As a result, when the buffer spring 60 is compressed while the ring 50 moves to the left, and the buffer spring 60 reaches the compression limit, the ring 50 presses the cylinder rod 42 while the cylinder rod 42 is also pressed. Move to the left. When the cylinder rod 42 moves to the left, the tool is unclamped while pushing the drawbar 20 in contact with its end to the left.

The cylinder rod 42 does not directly advance by the hydraulic pressure supplied in the above process, but a ring 50 and a spring 60 are provided to serve as a buffer. That is, since the buffer spring 60 disposed therebetween must be compressed until the ring 50 contacts the cylinder rod 42, the cylinder rod 42 is brought into contact with the drawbar 20 with a relatively small force. do.

Since the shock absorbing spring 60 absorbs a part of the shock to be transmitted to the drawbar 20 as described above, the drawbar 20 and the cylinder rod as compared to the conventional apparatus configured to move the cylinder rod 42 directly by the hydraulic supply. The impact on contact between the 42 is significantly reduced, so that the impact transmitted to the spindle support bearing 11 is also significantly reduced.

In addition, when the orifice 90 is additionally installed on the discharge passage of the second hydraulic port 72 as shown in FIG. 3, the fluid discharged to the second hydraulic port 72 at the time of unclamping exits the orifice. The resistance of 90 allows the shock to be further absorbed through the damping effect.

tool When clamping  (Lower half of FIGS. 2 and 3)

When clamping the tool, the drawbar 20 must be retracted.

To this end, the direction of hydraulic pressure must be reversed during tool unclamping. That is, while supplying fluid to the second hydraulic port 72 increases the hydraulic pressure of the B space, while the fluid is discharged to the first hydraulic port 71 to reduce the hydraulic pressure of the A space. As a result, the cylinder rod 42 moves to the right and moves the ring 50 to the right while the compressed shock absorbing spring 60 is restored again. As a result, a gap is formed between the cylinder body 42 and the draw bar 20, and the rotation of the draw bar 20 becomes possible. Meanwhile, the drawbar spring 30 pulls the tool and drawbar 20 strongly.

Although specific embodiments of the present invention have been described above, the spirit and scope of the present invention are not limited to the specific embodiments, and various modifications and changes can be made without departing from the spirit of the present invention. Those skilled in the art will understand.

Therefore, since the embodiments described above are provided to completely inform the scope of the invention to those skilled in the art, it should be understood that they are exemplary in all respects and not limited. The invention is only defined by the scope of the claims.

1 is a cross-sectional view showing the structure of a tool unclamping impact relief device according to the prior art.

Figure 2a is a cross-sectional view showing the structure of a tool unclamping impact relief device according to an embodiment of the present invention.

Figure 2b is a cross-sectional view showing the structure of a tool unclamping impact relief device according to a preferred embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

1: spindle spindle 2: drawbar

3: drawbar spring 4: drawbar cylinder

4-1: Cylinder Body 4-2: Cylinder Rod

5: lock nut 6: hook

7: Hydraulic supply part 7-1, 7-2: Hydraulic port

8: Bracket 9: Spring

10: spindle spindle 20: drawbar

30: drawbar spring 40: drawbar cylinder

41: cylinder body 42: cylinder rod

50: ring 60: buffer spring

70: hydraulic pressure supply unit 71: the first hydraulic port

72: second hydraulic port 73: solenoid valve

74: hydraulic supply unit 80: check valve

90: orifice

Claims (4)

As a tool unclamping shock mitigator of the machine tool spindle spindle 10, The drawbar 20 is inserted into the spindle spindle 10 so as to be able to move forward and backward, and the spindle spindle 10 unclamps the tool when moving forward and the spindle spindle 10 clamps the tool when moving backward. )Wow; A drawbar spring (30) installed between the spindle spindle (10) and the drawbar (20) to maintain the reverse state of the drawbar (20) when clamping the tool; The cylinder body 41 installed at the rear of the spindle spindle 10 and the cylinder rod 42 configured to be able to move back and forth within the cylinder body 41-the cylinder rod 42 when the clamping of the tool is performed. It is configured to push forward the drawbar 20 with a force greater than the restoring force of the drawbar spring (30) by advancing in contact with the drawbar (20), and when the clamping of the tool back to the draw Contact with the bar 20 is released—the drawbar cylinder 40 composed of; A ring (50) configured to move back and forth in the same direction as the cylinder body (41) inside the cylinder body (41); An impact installed between the ring 50 and the cylinder body 41 to contact the cylinder body 41 and the drawbar 20 when the cylinder body 41 is advanced for unclamping of the tool Buffer spring 60 to relieve pressure; Tool unclamping shock absorber of the machine tool spindle spindle (10) comprising a. The method of claim 1, Hydraulic pressure flows in when the cylinder rod 42 moves forward, and hydraulic pressure flows in when the cylinder rod 42 moves backward, and hydraulic pressure flows in the reverse direction of the cylinder rod 42. And a hydraulic pressure supply unit 70 including a second hydraulic port 72 through which hydraulic pressure flows out when the cylinder rod 42 is moved forward; Tool unclamping shock absorber of the machine tool spindle spindle (10) comprising a. The method of claim 2, A check valve (80) for adjusting the hydraulic pressure flowing into the second hydraulic port (72); Tool unclamping shock absorber of the machine tool spindle spindle (10) further comprising. The method of claim 2, An orifice (90) for buffering the hydraulic pressure flowing out to the second hydraulic port (72) when the cylinder rod (42) is advanced for unclamping of the tool; Tool unclamping shock absorber of the machine tool spindle spindle (10) further comprising.

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