Standard Components For Plastic Mold 2021

PRODUCT OVERVIEW ① COIL SPRINGS

■ Overview

■ Notes on handling MISUMI coil springs (excluding wire springs) are constantly undergoing design of optimal cross-sectional form in an effort to improve durability. Take great care of the notes below in order to use it as ease. ① Always use with a spring guide

High deflection type ● Coil spring load graph

φ 10.5−50

φ 10.5−52

φ 14.5−37

φ 11−42

φ 10.5−43

⑥ Set up an initial deflection When there is room for the coil spring to move vertically, it receives an impact force that causes it to bend midway or to buckle. Setting up an initial

When used without a spring guide, the coil spring may buckle or bend midway. This can cause it to break since the internal surface of the bend is subjected to concentrated high stress. Be sure to use a spring guide, such as a shaft and OD (outside diameter) guide, with the coil spring. ※ The best results are obtained by inserting a shaft all the way through the coil spring, from top to bottom, as an ID (inside diameter) guide. ② Clearance between spring ID and shaft It is recommended that the shaft diameter be set approximately 1.0mm smaller than the ID of the coil spring. When clearance between the spring and the shaft is insufficient, the coil springs internal surface may come into contact with the shaft and be subject to abrasion at that point. This will lead to the spring eventually breaking at the point of wear. Excessive clearance, on the other hand, can lead to buckling of the coil spring. When the coil spring has a long free length (i.e., free length/OD is 4 or high- er), set up a step on the shaft as shown in Fig. 1 to prevent the coil spring's internal surface from touching the shaft when it bends. ③ Clearance between spring OD and spot faced hole It is recommended that the spot faced hole diameter be set approximately 1.5mm larger than the coil spring OD. The coil spring expands in the outward direction when it deflects. Insufficient clearance between the spring and the spot faced hole restrains expansion, and the resulting concentration of stress can cause the coil spring to break. The spot faced hole configuration shown in Fig. 1 is ideal for a coil spring with a long free length. ④ Avoid a short shaft length and shallow spot faced hole depth If the guide is too short, the coil spring may touch the guides tip when it is compressed. The resulting friction could cause the coil spring to break. It is recommended that the guide length be set longer than half of the initial height. Also make sure to chamfer the shaft to around C3 level. ⑤ Do not use in excess of maximum deflection (300,000-times limit) (or use near solid height) When the coil spring is used in excess of the 300,000-times limit, the cross section begins to receive a stress higher than the theoretical value. This will cause the coil spring to break. And when the coil spring is used at around its solid height its active coils gradually adhere each other, increasing the spring constant value and causing the load curve to rise, as shown in Fig. 2. The resulting high stress that develops will cause the coil spring to break. Avoid using in conditions of over 300,000 cycles.

SWR

SWS

SWN

SWY

SWU Ultra high deection

L20

L15

L20

L15

Ultra high deection

High deection

Medium deection

Low deection

deflection stabilizes the top and bottom ends of the spring. ⑦ Avoid entrapment of debris or foreign matter

300

400

300

Debris or foreign matter that gets caught between the coils causes that part of the coil spring to stop functioning as active coils, making the other coils deflect as shown in Fig. 3. This effectively reduces the number of active coils, increasing the stress on the spring, and causing it eventually to break. Be careful not to let debris or foreign matter foul the coils. ⑧ Keep mounting faces parallel The coil spring should be mounted properly, with its mounting faces (top and bottom faces) parallel to each other. Misalignment can cause the spring to bend midway, subjecting the bend to high stress. This can cause to spring to break at that point. The same applies to the dies in which the coil spring is used, if the parallel alignment between the dies is poor, as shown in Fig. 4, the coil spring can bend midway or exceed the 300,000-times limit prema- turely. Keep the coil springs mounting faces as perfectly parallel as possible to prevent this from occurring. ⑨ Do not use coil springs in series If you use two coil springs in series, they will tend to bend, as shown in Fig. 5. This can cause them to move out of the shaft or spot faced holes. If this hap- pens, the coil spring will eventually break for the same reasons described in ① above. Due to spring load differences, moreover, the weaker spring is overcome by (and deflects more than) the stronger spring, as shown in Fig. 6. This will make the weaker spring more prone to damage, or cause it to break. Moreover, each spring constant when placing 2 springs in series is 1/2 that of a single spring. ⑩ Do not use two coil springs in parallel Use of two coil springs in parallel may result in the inner coils being sand- wiched between the outer coils, or vice versa, when they contract as shown in Fig.7. This can cause the coil springs to break for the same reason noted in ④ . ⑪ Do not use the coil spring horizontally When the coil spring is used horizontally, the internal surface of the spring will come into contact with the shaft, causing abrasion at those spots. The spring will eventually break at these weakened spots.

Operation frequency 1 million shots 300,000 shots

Deflection rate

65 ％

70 ％

60 ％

65 ％

40 ％

45 ％

30 ％

35 ％

50 ％

55 ％

● Operation frequency: 1 million shots

● Operation frequency: 300,000 shots

Load (N)

Load

200

Load

(kgf)

SWS

1470

150

1470

SWS

SWN

SWR

100

980

SWN

SWR

SWU

490

SWY

φ 10.5

φ 14.5 φ 12.5

φ 17 φ 16.5

φ 21 φ 20.5

φ 24.5 φ 26

φ 31 φ 30

φ 37

φ 43 φ 42

φ 46 φ 50

φ 10.5

φ 17 φ 14.5 φ 12.5 φ 12.5 φ 16.5

φ 21 φ 20.5

φ 26 φ 24.5

φ 31 φ 30

φ 37

SWS φ 43 φ 46 φ 50 φ 42 φ 52

φ SWY 11

φ 52

φ 12.5 φ SWY 11

SWS

● Load{kgf} ＝ Load N × 0.101972

Heavy Load Type

φ 6–30

φ 6–70

SWF Minimal load

SWL Light load

SWM Medium load

SWH Heavy load

SWC Extra minimal load

L15

L10

200

500

350

Operation frequency 1 million shots 500,000 shots 300,000 shots

Deflection rate

50 ％

55 ％

60 ％

40 ％

45 ％

50 ％

32 ％

36 ％

40 ％

25.5 ％

28.8 ％

32 ％

19.2 ％

21.6 ％

24 ％

MISUMI durability test conditions Fig.-1

Fig.-2

Fig.-3

● Operation frequency: 1 million shots

φ 6–70

φ 10–50

① Spring guide formula Shaft penetration

(kgf) Load

＜（ d － 1 ）

（ D ＋ 1 ）＜

Load (N)

(kgf) Load

SWB Extra heavy load

SWG Hyper heavy load

Foreign substance

L10

L15

1.0mm less than shaft diameter d

1500

350

200

14700

SWB

② Initial deflection 1.0mm ③ Amplitude

SWG

Operation frequency 1 million shots 500,000 shots 300,000 shots

SWH

1000

9800

Deflection rate

16 ％

18 ％

20 ％

16 ％

18 ％

20 ％

Deflection with 300,000-times limit value

SWM

（ D ＋ 1 ） Counterbore hole diameters

Shaft diameter （ d － 1 ）

④ Speed 180spm ※ The maximum number of durable operating times may vary depending on the service conditions.

500

SWF SWL

4900

d D

300,000-times limit value

Deection of solid height

Shaft shape Spotface shape

SWC

φ 6 φ 8

φ 30 φ 27 φ 25 φ 22 φ 20 φ 18 φ 16 φ 14 φ 12 φ 10

φ 35

φ 40

φ 50

φ 60

φ 70

φ D

Fig.-4

Fig.-5

Fig.-6

Fig.-7

● Load{kgf} ＝ Load N × 0.101972

● Operation frequency: 500,000 shots

● Operation frequency: 300,000 shots

(kgf) Load

Load (N)

SWB

Weak

SWB

1500

14700

Outer

SWH

SWG

Low deection High deection

Inner

SWH

SWG

Strong

1000

9800

1000

9800

SWM

SWL SWM

SWL

500

4900

500

4900

SWF

SWC

1141

1142

φ 6 φ 8

φ 10

φ 16 φ 12 φ 14 φ 18

φ 20

φ 25 φ 22 φ 27

φ 30

φ 35

φ 40

φ 50

φ 60

φ 70

φ D

φ 70

φ 6 φ 8

φ 10

φ 16 φ 12 φ 14 φ 18

φ 20

φ 25 φ 22 φ 27

φ 30

φ 35

φ 40

φ 50

φ 60

φ D

● Load{kgf} ＝ Load N × 0.101972