Numerical control machine for stretch bending and monitoring method for clamping force of round clamp thereof

Patent metadata

Field	Value
Publication number	US-11517953-B2
Application number	US-201916719929-A
Country	US
Kind code	B2
Filing date	Dec 18, 2019
Priority date	Jan 22, 2019
Publication date	Dec 6, 2022
Grant date	Dec 6, 2022

Abstract

A NC machine for stretch bending and monitoring method for clamping force of round clamp thereof is invented, which includes a round head clamp, a hydraulic system and a clamping force monitoring device. The round head clamp includes a housing, an internal module arranged in the housing and a positioning member for positioning the internal module in the housing. The hydraulic system includes a hydraulic rod and a hydraulic ram for pushing the hydraulic rod. The clamping force monitoring device includes a sensor and a data processing module. The present invention is suitable for the workpiece of different shapes and sizes. In this invention, the clamping force can be adjusted in real time when it needs to be changed, and this not only can avoid the problems of excessive energy consumption, excessive clamping marks and damage of the workpiece, but also save energy and protect the workpiece.

First claim

What is claimed is:

1. A numerical control machine for stretch bending, comprising:
a round head clamp, for clamping a workpiece; the round head clamp comprising:
a housing, the outer contour of the housing being in the shape of a frustum of a cone shape, and a positioning hole arranged on the side wall of the housing;
an internal module arranged in the housing; a mounting groove arranged in the bottom end of the internal module, and the mounting groove being coaxial with the housing; the internal module comprising:
a first component;
a second component; and
a third component; the first component, the second component and the third component axial setting around the housing and forming as a circular platform structure, the circular platform structure and the housing having a same cone angle; the first component and the second component forming as a notched structure, the third component inserted into the notch of the notched structure and having an L-shaped clamping space with the first component; and

a positioning member for positioning the internal module in the housing, connecting the housing to the internal module through the positioning hole;

a hydraulic system, for applying pressure to the round head clamp to clamp the workpiece, comprising:
a hydraulic rod, the hydraulic rod mounted in the mounting groove, and applied thrust to the circular platform structure to clamp the workpiece in the L-shaped clamping space; and
a hydraulic ram for pushing the hydraulic rod; and

a clamping force monitoring device, comprising:
a sensor, the sensor set in the mounting groove and for detecting the pressure between the hydraulic rod and the internal module; and
a data processing module; the data processing module used to calculate the clamping force between the internal module and the workpiece, and the clamping force being equal to the product of the pressure and the cotangent of half of the same cone angle.

2. The numerical control machine according to claim 1 , further comprising:
an upper computer, for dynamically displaying the clamping force.

3. The numerical control machine according to claim 2 , wherein when the clamping force is less than a preset clamping pressure value, the upper computer drives the hydraulic ram to increase oil pressure, and when the clamping force is greater than the preset clamping pressure value, the upper computer drives the hydraulic ram to reduce oil pressure, so as to make the clamping force be equal to the preset clamping pressure value.

4. The numerical control machine according to claim 3 , further comprising:
an oil-electric servo control system, for receiving control instruction sent by the upper computer and controlling the oil pressure of the hydraulic ram accordingly, the control instruction used for driving the hydraulic ram to increase or reduce the oil pressure.

5. The numerical control machine according to claim 4 , wherein the upper computer is configured to send the control instruction to the oil-electric servo control system by a clamping force control method using a mathematical model.

6. The numerical control machine according to claim 5 , wherein the clamping force control method comprises:
clamping workpieces made by different materials in the round head clamp;
changing the oil pressure of the hydraulic ram;
calculating the clamping force between various workpieces and the internal module to obtain the mathematical relationship between the clamping force and the oil pressure, then establishing a corresponding mathematical model; and
according to the mathematical model and the clamping force, carrying on a closed loop control to the hydraulic system by the oil-electric servo control system.

7. The numerical control machine according to claim 1 , wherein the mounting groove comprises a round hole and a disc cavity coaxial with the round hole; the radius of the disc cavity is larger than the radius of the round hole.

8. The numerical control machine according to claim 7 , wherein the hydraulic rod has a circular disc, and the radius of the circular disc is larger than the radius of the round hole;
the circular disc is set in the disc cavity.

9. The numerical control machine according to claim 8 , wherein the two ends of the second component are in the shape of an inferior arc bow.

10. The numerical control machine according to claim 9 , wherein the round hole is set in the second component and the third component.

11. The numerical control machine according to claim 8 , wherein the positioning member is a positioning pin.

12. The numerical control machine according to claim 8 , wherein the positioning hole is strip-shaped and extends parallel to an outer contour line of the housing.

13. The numerical control machine according to claim 1 , wherein the sensor is a pressure sensor which is fixed on the wall of the mounting groove, and the detection end of the sensor is in contact with the hydraulic rod.

14. The numerical control machine according to claim 1 , wherein the workpiece is one of a steel pipe, a square pipe, an H-shaped steel, an I-steel, a channel steel, an angle iron, a flat iron and an aluminum profile.

15. A monitoring method for clamping force of round clamp of a numerical control machine; the numerical control machine comprising:
a round head clamp, for clamping a workpiece; the round head clamp comprising:
a housing, the outer contour of the housing being in the shape of a frustum of a cone shape, and a positioning hole arranged on the side wall of the housing;
an internal module arranged in the housing; a mounting groove arranged in the bottom end of the internal module, and the mounting groove being coaxial with the housing; the internal module comprising:
a first component;
a second component; and
a third component; the first component, the second component and the third component axial setting around the housing and forming as a circular platform structure, the circular platform structure and the housing having a same cone angle; the first component and the second component forming as a notched structure, the third component inserted into the notch of the notched structure and having an L-shaped clamping space with the first component; and

a positioning member for positioning the internal module in the housing, connecting the housing to the internal module through the positioning hole;

a hydraulic system, for applying pressure to the round head clamp to clamp the workpiece, comprising:
a hydraulic rod, the hydraulic rod mounted in the mounting groove, and applied thrust to the circular platform structure to clamp the workpiece in the L-shaped clamping space; and
a hydraulic ram for pushing the hydraulic rod; and

a clamping force monitoring device, comprising:
a sensor, the sensor set in the mounting groove and for detecting the pressure between the hydraulic rod and the internal module; and

a data processing module; the data processing module used to calculate the clamping force between the internal module and the workpiece, and the clamping force being equal to the product of the pressure and the cotangent of half of the same cone angle;

wherein the monitoring method comprises:
detecting the pressure between the hydraulic rod and the internal module;
calculating half of the cone angle of the circular platform structure; and
calculating the clamping force between the internal module and the workpiece, and the clamping force is equal to the product of the pressure and the cotangent of half of the same cone angle.

16. The monitoring method according to claim 15 , wherein the

Assignees

• Univ Hefei Technology

Inventors

• Zhou Lihua
• Cao Zhenxin

Classifications

• G05B19/182

  characterised by the machine tool function, e.g. thread cutting, cam making, tool direction control (G05B19/21 - G05B19/40 take precedence) · CPC title

• B21D7/02 Primary

  over a stationary forming member; by use of a swinging forming member or abutment · CPC title

• B21D11/02 Primary

  Bending by stretching or pulling over a die (working sheet metal of limited length by stretching B21D25/00) · CPC title

• B21D7/12

  with program control · CPC title

• G05B2219/36203

  Bending of workpiece, also for long slender workpiece · CPC title