1.3
Reusability
One of the feature of the HARDLOCK products is that they can be re-used several times.
Performace after repeated usage and information relating to torque and axial force
is seen below
Test Conditions
Specimens
Bolt
：M12×70 Strenght Class 4.8 、Surface Treatment: Trivalent Chromate
Nut
：HLN�Strenght Class 4�Surface Treatment:�Trivalent Chromate
Tightening (1st)
1st
Bolt Preload [kN] 25 20 15 10 Concave nut one-side adhesion 5 0 0
5
10
15
20
25
30
35
40
45
50
Torque [N・m] Tightening (2nd), (11th)
2nd
25 11th
Preload [N]
20 15 10 5 0 0
10
20
Torque [N・m] 30
40 0
1/6
10
20
30
Torque [N・m] 40
Test Method
(1) Tighten the HLN and commence the tightening test.
(2) Conduct the Junker test to confirm self-locking results.
(3) After conducting the Junker test, conduct the tightening test.
(4) Attaching and detaching 8 times and perform re-tightening test。
(5) Repeat (1)〜(4)、Reapeat (2) until you have attatched and detatched the nut 51times。
Tightening Method
Tighten convex nut to 70% of yield point
Tighten concave nut until one-sided adhesion
Junker test result after 1st tightening
25 1st / Remaining Preload : 93%
Preload [kN] 20 15 10 5 0 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Cycles Junker test result after 11th tightening
25 11th / Remaining Preload : 95%
Preload [kN] 20 15 10 5 0 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Cycles 2/6
Test Schematic
Tightening
Test ×1 Tightening
Test Junker Test ×10 Junker Test ×5 Tightening (1st) The junker test was conducted 6 6mes and the nuts where 6ghtened of a total of 51 6mes . Below, we show 10 before and a?er test results of the 6ghtening test of before and a?er test results of the Juker-­‐type test Tightening (12th), (21st)
12th 12th
12th 21st
25000 20 20000 15 15000 10 10000 5 5000 Preload [N] Preload [N] 25 0 0 5 10 15 20 25 Torque [N・m] 30 35 0 40 0 5 10 15 20 25 Torque [N・m] 30 35 40 Tightening (22nd), (31st)
22nd 31th 31st
22nd
25 Preload [N] 20 15 10 5 0 0 5 10 15 20 25 Torque [N・m] 30 35 40 0 3/6
5 10 15 20 25 Torque [N・m] 30 35 40 Junker Test Results
�・Amplitude：±0.35 mm
�・Initial Preload：70％ of yield point
�・1500 cycles
When conduc6ng the Junker test, lubricant is applied. This is to avoid residual axial force due to factors other than the self-­‐locking func6on and to prevent thread seizure. For example, if there is thread seizure, dents on the bolt or if the nut gets caught on the roughness of the bearing surface, rota6onal loosening may not occur. By applying a lubricant to eliminate these influences, it is possible to measure the pure sef-­‐locking performance.
Junker test result after 21st tightening
25 21st / Remaining Preload : 95%
Preload [kN] 20 15 10 5 0 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Cycles Junker test result after 31st tightening
25 31st / Remaining Preload : 97%
Preload [kN] 20 15 10 5 0 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Cycles 4/6
By looking at the results of the reapted aKaching and detaching test so far, you can see that there are no major changes in 6ghtening characteris6cs of the HARDLOCK Nut even a?er repeated usage. Take no6ce to the change in axial force when 6ghtening the Concave Nut. When 6ghtening the Concave nut you can see that there is almost no change in the ini6al axial force. By looking at the results from the Junker test, the HARDLOCK Nut maintains a high axial force and holds a sufficient self-­‐locking performance.
Tightening (32nd), (41st)
32nd 41st 41st
32nd
25 Preload [N] 20 15 10 5 0 0 5 10 15 20 25 Torque [N・m] 30 35 40 0 5 10 15 20 25 Torque [N・m] 30 35 40 Tightening (42nd). (51st)
42nd 42nd
25 51st 51st
Preload [N] 20 15 10 5 0 0 5 10 15 20 25 Torque [N・m] 30 35 40 0 5/6
5 10 15 20 25 30 35 40 By looking at the test results so far, first, there is liKle change in the 6ghtening characteris6cs, during repeated use , the same 6ghtening method can be adopted. Then as can be seen from the results of the Junker test the HARDLOCK Nut maintained sufficient locking performance even a?er 51 6mes of aKaching and detaching. Therefore, you can see that the HARDLOCK Nut can provide an sufficiant self-­‐locking performance even a?er repeated usage.
Junker test result after 41st tightening
25 Remaining Preload：93％ 41st / Remaining Preload : 93%
Preload 20 15 10 5 0 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Cycles Junker test result after 51st tightening
25 Remaining Preload：93％ 51st / Remaining Preload : 93%
Preload [kN] 20 15 10 5 0 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 Cycles 6/6