Process and device for setting up and controlling a hydraulic chucking of one or a plurality of bolts

• US 20100005663A1
• Filed: 08/20/2007
• Published: 01/14/2010
• Est. Priority Date: 09/01/2006
• Status: Active Grant

• Current Assignee: ABet SKF
• Original Assignee: ABet SKF
• Inventors: Monville, Jean-Michel
• Granted Patent: US 8,261,421 B2
• Time in Patent Office: Days
• US Class Current: 29/898.90
• CPC Class Codes: B23P 19/067 Bolt tensioners for hand tools B25B29/02
• CPC Class Codes: B25B 29/02 Bolt tensioners
• CPC Class Codes: G01L 5/24 for determining value of torque or twisting moment for tightening a nut or other member which is similarly stressed
• CPC Class Codes: Y10T 29/497 Pre-usage process, e.g., preloading, aligning
• CPC Class Codes: Y10T 29/49764 with testing or indicating
• CPC Class Codes: Y10T 29/49863 with prestressing of part
• CPC Class Codes: Y10T 29/49948 Multipart cooperating fastener [e.g., bolt and nut]
• CPC Class Codes: Y10T 29/53022 with means to test work or product

Abstract

A method of establishing and checking the axial preload in a tightening portion (34) of at least one shank of the screw or stud type (4). The establishing of the preload involves a step of tensioning an extension portion (33) of the shank (4) comprising the tightening portion (34) using a shank (4) gripper member (9) and a tensioner (6). The checking method involves a step in which, prior to establishing the preload, the tensioner is brought into a rest configuration and the gripper member (9) is brought into contact with the tensioner (6) in said rest configuration, and a step in which, having established the preload, the tensioner is returned to said rest configuration, and the tensioner in said rest configuration is pressed toward one of the ends of the extension portion (33) and the difference between the initial length (Liθ) and the final length (Lfθ) of the extension portion (33) is compared against a threshold.

Claims

1. A method of establishing and checking the axial preload in a tightening portion of at least one shank of the screw or stud type, the method comprising the steps of:

tensioning an extension portion of the shank having the tightening portion using a shank gripper member and a tensioner to establish a preload;

disposing the tensioner in a rest configuration and bringing the gripper member into contact with the tensioner in said rest configuration prior to establishing the preload;

returning the tensioner to said rest configuration after establishing the preload, the tensioner in said rest configuration being pressed toward one end of the extension portion; and

comparing the difference between the initial length and the final length of the extension portion with a threshold.

4. The method as claimed in claim 1,

wherein the at least one shank includes at least three parallel shanks, each shank having a tightening portion of the same length as the tightening portion of each other shank, and the step of establishing the preload includes employing a plurality of shank gripper members each located at one of the ends of the extension portion of a separate one of the shanks, the relative position of the other end of each extension portion being unchanged by establishing of the preload, and

further comprising the step of bringing each gripper member into contact with a reference surface of the tensioner in the initial position prior to establishing the preload, such that once the preload has been established, the reference surface is pressed firmly into a final position against the three gripper members and the distance between the initial position and the final position of the reference surface is measured at at least three measurement points.

5. The method as claimed in claim 4, in which a minimal difference between the final length and the initial length of the extension portion of the shank is calculated for each one of the three shanks as a function of the distances measured.

2. (canceled)

3. The method as claimed in claim, wherein:

the step of tensioning an extension portion includes tensioning at least two shanks each having a tightening portion of the same length and the step of comparing the difference between initial and final lengths includes separately comparing the initial and final lengths of each of the at least two shanks; and

,

further comprising the step of identifying the one of the at least two shanks that exhibits the smallest difference between the final length and the corresponding initial length in order to identify which shank has the minimum preload.

6. A device for establishing and checking the axial preload of at least one shank when tightening a component, the device comprising:

a gripper member located on the at least one shank; and

a tensioner including a body, a piston having a bearing surface for bearing against a complementary surface of the gripper member, the tensioner body having a bearing surface for bearing against a complementary surface of the component that is to be tightened, the tensioner having a rest configuration in which the piston and body bearing surfaces are fixed relative to one another, the piston and body bearing surfaces being configured to apply tension to the shank when the tensioner is not in the rest configuration;

a pressing means for pressing one of the bearing surfaces of the tensioner against the corresponding complementary surface; and

a comparison means for comparing the distance between the other bearing surface of the tensioner at rest and the corresponding complementary surface with a threshold.

7. The device as claimed in claim 6, in which the pressing means is configured to press the piston bearing surface against the corresponding complementary surface of the gripper member, while at the same time keeping the gripper member fixed with respect to the at least one shank.

8. The device as claimed in claim 6, wherein the tensioner includes a plurality of pistons, one piston for each one of a plurality of shanks being checked, and the device further comprises a measurement means configured to measure the distance between the bearing surface of the tensioner body and the component that is to be tightened at at least three measurement points.

9. The device as claimed in claim 8, further comprising a calculation means configured to determine which of the plurality of shanks has the lowest tension as a function of the at least three distances measured.

10. The device as claimed in claim 8, in which the tensioner has one rest configuration in which the pistons are immobilized by internal limit stops of the tensioner body, a reference surface of the tensioner being defined by the plurality of bearing surfaces of the pistons at rest;

the gripper members of the plurality of shanks being checked are in contact with the reference surface of the tensioner before the preload is established; and

the pressing means being configured to press the reference surface of the tensioner firmly against at least three contact gripper members when the preload is established.

11. The device as claimed in claim 8, in which the tensioner body is of annular overall shape and configured to check a plurality of shanks distributed around a circle and are parallel to the axis of the annular shape.

12. The device as claimed in claim 11, in which the tensioner body bearing surface has an overall shape of a ring;

and the pressing means bearing against the component that is to be tightened and being capable of moving the annular body of the tensioner at three support points distributed about the ring.