阅读说明：本技术 大通孔床头箱主轴的轴承预紧方法 (Bearing pre-tightening method for spindle of large-through-hole headstock ) 是由 李革志 卢传杰 秦春红 成占华 于洋 于 2019-10-16 设计创作，主要内容包括：本发明涉及机床安装技术,具体涉及一种大通孔床头箱主轴的轴承预紧方法,包括以下步骤：S1)测量前轴承在有负载和无负载的工况下轴承内环的轴向位移差ΔH1；S2)测量后轴承在有负载和无负载的工况下轴承内环的轴向位移差ΔH2；S3)将前轴承和后轴承分别预紧装配至主轴的前后端,保证预紧前后前轴承的轴承内环的轴向位移差为ΔH1、后轴承的轴承内环的轴向位移差ΔH2。该方法有效调整大通孔主轴轴承预紧力,特别是在重负荷状况下,使主轴精度稳定、可靠。(The invention relates to a machine tool mounting technology, in particular to a bearing pre-tightening method for a spindle of a large-through-hole headstock, which comprises the following steps: s1) measuring the axial displacement difference delta H1 of the inner ring of the bearing under the working conditions of load and no load of the front bearing; s2) measuring the axial displacement difference delta H2 of the inner ring of the bearing under the working conditions of load and no load of the rear bearing; s3) respectively pre-tightening the front bearing and the rear bearing to the front end and the rear end of the main shaft, and ensuring that the axial displacement difference of the bearing inner rings of the pre-tightened front bearing and the pre-tightened rear bearing is delta H1 and the axial displacement difference of the bearing inner rings of the rear bearing is delta H2. The method effectively adjusts the pre-tightening force of the main shaft bearing with the large through hole, and particularly enables the main shaft to be stable and reliable in precision under the heavy load condition.)

1. A bearing pre-tightening method for a spindle of a large-through-hole headstock comprises a front bearing (3) and a rear bearing (13), and is characterized by comprising the following steps:

s1) measuring the axial displacement difference delta H1 of the inner ring of the bearing of the front bearing (3) under the working conditions of load and no load;

s2) measuring the axial displacement difference delta H2 of the inner ring of the bearing under the working conditions of load and no load of the rear bearing (13);

s3) respectively pre-tightening the front bearing (3) and the rear bearing (13) to be assembled at the front end and the rear end of the main shaft (5), and ensuring that the axial displacement difference of the bearing inner rings of the pre-tightened front bearing (3) and the pre-tightened rear bearing (13) is delta H1 and the axial displacement difference of the bearing inner rings of the rear bearing (13) is delta H2.

2. The method for pre-tightening the bearing of the spindle of the headstock with the large through hole according to claim 1, wherein in the step S3), the pre-tightening assembly method of the front bearing (3) and the rear bearing (13) comprises the following steps:

s3.11) respectively and correspondingly pressing the front gland (2) and the front gland locking nut (4) against the bearing outer ring and the bearing inner ring of the front bearing (3), and keeping the front bearing (3) in a no-load state;

s3.12) measuring the distance C1 between the bearing inner ring of the front bearing (3) and the front end face of the main shaft (5);

s3.13) pressing the bearing inner ring of the front bearing (3) by using the front gland locking nut (4), measuring the distance C1 'between the bearing inner ring of the front bearing (3) and the front end surface of the main shaft (5) at the moment, and stopping pressing the front gland locking nut (4) until C1' -C1 = delta H1.

3. The method for preloading the bearing of the spindle of the large through-hole headstock of claim 2, wherein in the step S3), the method for preloading the rear bearing (13) comprises:

s3.21) pressing the bearing outer ring of the rear bearing (13) by using the rear gland (12); pressing the bearing inner ring of the rear bearing (13) by using an outer spacer (14) and a rear gland (12), and then pressing the outer spacer (14) by using a rear gland locking nut (15); and the rear bearing (13) is kept in a no-load state;

s3.22) measuring the distance C2 between the rear end face of the outer spacer (14) and the rear end face of the main shaft (5);

s3.23) pressing the bearing inner ring of the rear bearing (13) by using the outer spacer (14) of the rear gland locking nut (15), measuring the distance C2 'between the rear end surface of the outer spacer (14) and the rear end surface of the main shaft (5) at the moment, and stopping pressing the rear gland locking nut (15) until C2' -C2 = delta H2.

4. The method for pre-tightening the bearing of the spindle of the headstock of claim 1, wherein in step S2), the rear bearing (13) is a double-row tapered roller bearing and is provided with an inner ring spacer (16), and the method for measuring the axial displacement difference Δ H2 comprises:

s2.1) dismounting an inner ring spacer (16) of the rear bearing (13), and measuring a gap L between two bearing inner rings of the rear bearing (13) after loading;

s2.2) loading the bearing inner ring to determine the axial displacement difference delta H2 of the bearing inner ring;

s2.3) polishing the thickness of the inner ring spacer (16) to a size L, and then installing the inner ring spacer back into the rear bearing (13).

5. The method for pre-tightening the bearing of the spindle of the large-through-hole headstock of claim 3, which is characterized in that: the end face circumferences of the front gland locking nut (4) and the rear gland locking nut (15) are uniformly provided with a plurality of screw holes, and the corresponding bearing inner rings are respectively pressed through a plurality of screws (7).

6. The method for pre-tightening the bearing of the spindle of the large-through-hole headstock of claim 5, which is characterized in that: the measuring method of the distances C1 and C1' comprises the following steps: c1 is measured through a screw hole on the end surface of the front gland locking nut (4); then reserving a screw hole on the end face of the front gland locking nut (4), assembling screws (7) on the residual screw holes, and screwing down the screws, wherein the distance C1' is measured through the reserved screw hole; stopping screwing the screw (7) when C1' -C1 = delta H1, and screwing the screw (7) into the screw hole reserved finally to be tightly pressed;

the distances C2 and C2 'are measured in the same manner as the distances C1 and C1' described above.

7. The method for pre-tightening the bearing of the spindle of the large through hole headstock according to claim 5, characterized in that the number of the screw holes arranged on the circumference of the end surface of the front gland lock nut (4) and the rear gland lock nut (15) is 10 ~ 18, and the diameter of the screw holes is M12 ~ M16.

8. The method for pre-tightening the bearing of the spindle of the large-through-hole headstock of claim 2, which is characterized in that: the front bearing (3) is a double-row cylindrical roller bearing.

Technical Field

The invention relates to the mounting technology of machine tools, in particular to a bearing pre-tightening method for a spindle of a large-through-hole headstock.

Background

In the assembly of the spindle of the headstock of the large-through-hole machine tool, the spindle inner holes are large because workpieces pass through the spindle inner holes, and the bearings for fixing the spindle are enlarged accordingly. In order to prevent the unbalanced moment generated by the gap between the inner ring and the outer ring of the bearing when the main shaft rotates from affecting the rotation stability and the rotation precision of the main shaft, referring to fig. 1 and fig. 2, a double-row cylindrical roller bearing (such as NNU4984K P5) is usually adopted to control the radial runout of the main shaft, and a double-row tapered roller bearing (such as 351984P 5) is adopted to limit the axial play of the main shaft, so that the assembly precision of the main shaft after the bearing is installed is ensured. The positioning mode has larger bearing, and the required axial jacking force of the nut is also larger. However, the existing assembly mode is only to increase the screwing force of the nut, the acting force is in the circumferential direction of the nut, the axial pressure of the bearing is converted into limited, the bearing is not easy to detect, whether the bearing is tightly propped or not is not known after the assembly, the positioning of the main shaft in a headstock due to the bearing gap is unreliable, the precision is unstable, and the precision is seriously out of tolerance especially under the heavy load condition.

Disclosure of Invention

In order to solve the problems, the invention provides a bearing pre-tightening method for a spindle of a large-through-hole headstock, which is simple, accurate and convenient to operate, and solves the problems of unreliable positioning and over-precision of the spindle of the headstock of a machine tool in the headstock due to bearing clearance. The technical scheme adopted by the invention is as follows:

a bearing pre-tightening method for a spindle of a large-through-hole headstock comprises a front bearing and a rear bearing, and comprises the following steps of:

s1) measuring the axial displacement difference delta H1 of the inner ring of the bearing under the working conditions of load and no load of the front bearing;

s2) measuring the axial displacement difference delta H2 of the inner ring of the bearing under the working conditions of load and no load of the rear bearing;

s3) respectively pre-tightening the front bearing and the rear bearing to the front end and the rear end of the main shaft, and ensuring that the axial displacement difference of the bearing inner rings of the pre-tightened front bearing and the pre-tightened rear bearing is delta H1 and the axial displacement difference of the bearing inner rings of the rear bearing is delta H2.

In the step S3), the method for pre-tightening and assembling the front bearing and the rear bearing includes: assembling an opening locking nut at the opening end of the front end of the main shaft;

s3.11) respectively and correspondingly pressing the front gland and the front gland locking nut on the bearing outer ring and the bearing inner ring of the front bearing, and keeping the front bearing in a no-load state;

s3.12) measuring the distance C1 between the bearing inner ring of the front bearing and the front end face of the main shaft at the moment;

s3.13) compressing the bearing inner ring of the front bearing by using the front gland locking nut, measuring the distance C1 'between the bearing inner ring of the front bearing and the front end surface of the main shaft at the moment, and stopping compressing the front gland locking nut until C1' -C1 = delta H1;

in the step S3), the method for pre-tightening and assembling the rear bearing includes:

s3.21) pressing the bearing outer ring of the rear bearing by using the rear gland; pressing the bearing inner ring of the rear bearing by using the outer spacer and the rear gland, and then pressing the outer spacer by using a rear gland locking nut; and the rear bearing is kept in a no-load state;

s3.22) measuring the distance C2 between the rear end face of the outer spacer and the rear end face of the main shaft at the moment;

s3.23) the outer spacer of the rear gland lock nut is used for compressing a bearing inner ring of the rear bearing, the distance C2 'between the rear end face of the outer spacer and the rear end face of the main shaft at the moment is measured, and the compression of the rear gland lock nut is stopped until C2' -C2 = delta H2.

In the step S2), the rear bearing is a double-row tapered roller bearing and is provided with an inner ring spacer, and the method for measuring the axial displacement difference Δ H2 includes:

s2.1) dismounting an inner ring spacer of the rear bearing, and measuring a gap L between two bearing inner rings of the rear bearing after loading;

s2.2) loading the bearing inner ring to determine the axial displacement difference delta H2 of the bearing inner ring;

s2.3) polishing the thickness of the inner ring spacer to a size L, and then installing the inner ring spacer back into the rear bearing.

According to the bearing pre-tightening method for the spindle of the large-through-hole headstock, the end surface circumferences of the front gland locking nut and the rear gland locking nut are uniformly provided with a plurality of screw holes, and the corresponding bearing inner rings are respectively pressed through the plurality of screws.

In the method for pre-tightening the bearing of the spindle of the large through hole headstock, the distances C1 and C1' are measured by the following steps: c1 is measured through a screw hole on the end face of the front gland lock nut; then reserving a screw hole on the end face of the locking nut of the front gland, assembling screws on the residual screw holes for screwing, and measuring the distance C1' through the reserved screw hole; stopping screwing the screw when C1' -C1 = delta H1, and screwing the screw into the screw hole reserved finally to be tightly pressed;

the distances C2 and C2 'are measured in the same manner as the distances C1 and C1' described above.

According to the bearing pre-tightening method for the spindle of the large through hole headstock, the number of the screw holes formed in the end surface circumferences of the front gland locking nut and the rear gland locking nut is 10 ~ 18, and the diameter of each screw hole is M12 ~ M16.

According to the bearing pre-tightening method for the spindle of the large through hole headstock, the front bearing is a double-row cylindrical roller bearing.

The invention has the beneficial effects that: the method effectively adjusts the pre-tightening force of the main shaft bearing with the large through hole, and particularly enables the main shaft to be stable and reliable in precision under the heavy load condition. The bearing is pre-tightened according to data (such as delta H), the pre-tightening force is adjusted, the main shaft adjusting precision can be monitored simultaneously, the radial runout and the axial runout of the main shaft can be guaranteed within the precision requirement range (such as 0.01 mm), the machine tool headstock assembled by the method is proved to be reliable and practical through practice, and the machine tool headstock passes the durability acceptance check at a user.

Drawings

Fig. 1 and fig. 2 are schematic structural diagrams of a front and rear bearing preloading process in the prior art respectively.

FIG. 3 is a schematic diagram comparing the pretensioning process of the front bearing according to the embodiment of the present invention;

FIG. 4 is a schematic diagram comparing the pretensioning process of the rear bearing according to the embodiment of the present invention.

In the figure: 1 is a headstock, 2 is a front gland, 3 is a front bearing, 4 is a front gland lock nut, 5 is a main shaft, 6 is an open lock nut, 7 is a screw, 12 is a rear gland, 13 is a rear bearing, 14 is an outer spacer, 15 is a rear gland lock nut, and 16 is an inner ring spacer.

Detailed Description

The invention is further explained below with reference to the drawings.

The bearing pre-tightening in the existing headstock 1 is to adjust the pre-tightening force of the main shaft bearing with a large through hole only by backing up the front gland locking nut 4 and the rear gland locking nut 15 and closing against the inner ring of the bearing, at the moment, the acting force is at the outer diameter of the nut, and the pre-tightening of the bearing is realized by the jacking force formed by the rotation of the nut.

The front bearing 3 in the headstock 1 in this embodiment is a double row cylindrical roller bearing NNU4894K P5 and the rear bearing 13 is a double row tapered roller bearing 351984P 5. The bearing pre-tightening method for the main shaft in the large through hole headstock 1 comprises the following steps:

s1) measuring the axial displacement difference delta H1 of the inner ring of the bearing of the front bearing 3 under the working conditions of load and no load;

s2) measuring the axial displacement difference delta H2 of the inner ring of the bearing under the working conditions of load and no load of the rear bearing 13;

s3) respectively pre-tightening the front bearing 3 and the rear bearing 13 to the front end and the rear end of the main shaft 5, and ensuring that the axial displacement difference of the bearing inner rings of the pre-tightened front bearing 3 and the pre-tightened rear bearing 3 is delta H1 and the axial displacement difference of the bearing inner rings of the rear bearing 13 is delta H2.

In the step S3), the method for pre-tightening and assembling the front bearing 3 and the rear bearing 13 includes: firstly, assembling an opening locking nut 6 at the opening end of the front end of a main shaft 5;

s3.11) correspondingly pressing the front gland 2 and the front gland locking nut 4 against the bearing outer ring and the bearing inner ring of the front bearing 3 respectively, and keeping the front bearing 3 in a no-load state;

s3.12) measuring the distance C1 between the inner bearing ring of the front bearing 3 and the front end face of the main shaft 5;

s3.13) compressing the bearing inner ring of the front bearing 3 by using the front gland locking nut 4, measuring the distance C1 'between the bearing inner ring of the front bearing 3 and the front end surface of the main shaft 5 at the moment, and stopping compressing the front gland locking nut 4 until C1' -C1 = delta H1;

in the step S3), the method for pre-tightening and assembling the rear bearing 13 includes:

s3.21) pressing the bearing outer ring of the rear bearing 13 by using the rear gland 12; pressing the inner bearing ring of the rear bearing 13 by using the outer spacer 14 and the rear gland 12, and then pressing the outer spacer 14 by using the rear gland locking nut 15; and the rear bearing 13 is kept in a no-load state; the outer spacer 14 is formed with a splash guard to prevent oil leakage.

S3.22) measuring the distance C2 between the rear end face of the outer spacer 14 and the rear end face of the main shaft 5;

s3.23) pressing the outer spacer 14 of the rear gland lock nut 15 to press the inner ring of the bearing of the rear bearing 13, measuring the distance C2 'between the rear end face of the outer spacer 14 and the rear end face of the main shaft 5 at this time, and stopping pressing the rear gland lock nut 15 until C2' -C2 = Δ H2.

In the step S2), the rear bearing 13 is provided with the inner ring spacer 16, and the method for measuring the axial displacement difference Δ H2 includes:

s2.1) detaching the inner ring spacer 16 of the rear bearing 13, and measuring the gap L between the two bearing inner rings of the rear bearing 13 after loading;

s2.2) loading the bearing inner ring to determine the axial displacement difference delta H2 of the bearing inner ring;

s2.3) polishing the thickness of the inner ring spacer 16 to a size L, and then installing the inner ring spacer back into the rear bearing 13.

According to the bearing pre-tightening method for the spindle of the large-through-hole headstock, the end surface circumferences of the front gland locking nut 4 and the rear gland locking nut 15 are uniformly provided with a plurality of screw holes, and the corresponding bearing inner rings are respectively pressed through a plurality of screws 7.

In the method for pre-tightening the bearing of the spindle of the large through hole headstock, the distances C1 and C1' are measured by the following steps: c1 is measured through a screw hole on the end face of the front gland lock nut 4; then reserving a screw hole on the end face of the front gland locking nut 4, assembling screws 7 on the residual screw holes, and screwing down the residual screw holes, wherein the distance C1' is measured through the reserved screw hole; stopping screwing the screw 7 when C1' -C1 = Δ H1, and screwing the screw 7 into the screw hole reserved finally to be tightly pressed; monitoring the end surface and the inner hole of the main shaft 5 by using a dial indicator to ensure that the runout of the main shaft is within 0.01 mm;

the distances C2 and C2 'are measured in the same manner as the distances C1 and C1' described above.

According to the bearing pre-tightening method for the spindle of the large-through-hole headstock, the number of the screw holes formed in the end surface circumferences of the front gland locking nut 4 and the rear gland locking nut 15 is 10 ~ 18, and the diameter of each screw hole is M12 ~ M16.