沉头螺钉用沉孔（不含DIN EN 27721头螺钉）

Countersinks for countersunk head screws (except screws with DIN EN 27721 head)

ICS 21.060.01

Supersedes December 1980 edition.

Senkungen für Senkschrauben (ausgenommen Senkschrauben mit Köpfen nach DIN EN 27721)

In keeping with current practice in standards published by the International Organization for Standardization (ISO), a comma has been used throughout as the decimal marker.

Foreword

This standard has been prepared by Technical Committee Fachgrundnormen of the Normenausschuss Mechanische Verbindungselemente (Fasteners Standards Committee).

The revision of this standard reflects the developments that have taken place since the last edition was published in December 1980, a large number of national standards on countersunk head screws for which countersinks were specified in the former edition of this standard having since been superseded by ISO Standards and countersinks for countersunk head screws with DIN EN 27721 heads now being specified in DIN 66. As a result, this standard now only specifies countersinks for those screws for which national standards still exist.

Amendments

This standard differs from the December 1980 edition as follows.

a) Countersinks for countersunk head screws with ISO 7721 head as well as countersinks for metric screws, self-cutting screws, thread-grooving screws, tapping screws, and type A fine series wood screws are no longer included (cf. DIN 66).

b) Type F countersinks have been modified to fit hexagon socket countersunk head screws as in DIN EN ISO 10642.

Previous editions

DIN 74-1: 1971-01, 1980-12.

All dimensions are in millimetres.

1 Scope

This standard specifies dimensions and designation of countersinks for countersunk heads screws as in DIN 95, DIN 97, DIN 7969, DIN 7995, DIN 7997, and DIN EN ISO 10642.

NOTE: Countersinks for countersunk head screws with DIN EN 27721 head are specified in DIN 66.

Continued on pages 2 to 4.

Translation by DIN-Sprachendienst.

In case of doubt, the German-language original should be consulted as the authoritative text.

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2 Normative references

This standard incorporates, by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text, and the titles of the publications are listed below. For dated references, subsequent amendments to or revisions of any of these publications apply to this standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies.

DIN 66	Countersinks for countersunk head screws with ISO 7721 common head style
DIN 95	Slotted raised countersunk (oval) head wood screws
DIN 97	Slotted countersunk (flat) head wood screws
DIN 7969	Slotted countersunk head screws for structural steel bolting for supply with or without nut
DIN 7995	Cross recessed raised countersunk head wood screws
DIN 7997	Cross recessed countersunk head wood screws
DIN EN 20273	Fasteners – Clearance holes for bolts and screws (ISO 273 : 1979)
DIN EN 27721	Countersunk head screws – Head configuration and gauging (ISO 7721 : 1983)
DIN EN ISO 10642	Hexagon socket countersunk head screws (ISO 10642 : 1997)

3 Dimensions and designation

Countersink dimensions shall be as given in figures 1 to 3 and tables 1 to 3.

3.1 Type A, for countersunk head wood screws as in DIN 97 and DIN 7997, and raised countersunk head wood screws as in DIN 95 and DIN 7995.

Figure 1: Type A countersink dimensions (notation)

Designation of a countersink of type A for a 4 mm screw thread diameter:

Countersink DIN 74 – A4

Table 1: Type A countersink dimensions

Thread size	1,6	2	2,5	3	3,5	4	4,5	5	5,5	6	7	8
d11) H13	1,8	2,4	2,9	3,4	3,9	4,5	5	5,5	6	6,6	7,6	9
d2 H13	3,7	4,6	5,7	6,5	7,6	8,6	9,5	10,4	11,4	12,4	14,4	16,4
t1 ≈	0,9	1,1	1,4	1,6	1,9	2,1	2,3	2,5	2,7	2,9	3,3	3,7
1) Diameter of clearance hole, medium series, as in DIN EN 20273.

3.2 Type E, for countersunk head screws as in DIN 7969.

Figure 2: Type E countersink dimensions (notation)

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Designation of a countersink of type E for a 12 mm screw thread diameter

Countersink DIN 74 – E12

Table 2: Type E countersink dimensions

Thread size	10	12	16	20	22	24
d11) H13	10,5	13	17	21	23	25
d2 H13	19	24	31	34	37	40
t1 ≈	5,5	7	9	11,5	12	13
α ±1°	75°			60°
1) Diameter of clearance hole, medium series, as in DIN EN 20273.

3.3 Type F, for hexagon socket countersunk head screws as in DIN EN ISO 10642.

Figure 3: Type F countersink dimensions (notation)

Designation of a countersink of type F for a 12 mm screw thread diameter:

Countersink DIN 74 – F12

Table 3: Type F countersink dimensions

Thread size	3	4	5	6	8	10	12	14	16	20
d11) H13	3,4	4,5	5,5	6,6	9	11	13,5	15,5	17,5	22
d2 H13	7,5	10	12,5	14,5	19	23,5	28	32	35	41,5
t1 ≈	1,8	2,4	3,1	3,6	4,6	6	7	8	8,5	9,5
α ±1°	90°
1) Diameter of clearance hole, medium series, as in DIN EN 20273.

3.4 Other depths of countersink

Where countersinks of depth t₁, deviating from that given in tables 1 to 3 are required (e.g. 3 mm for an A4 countersink), this shall be indicated in the designation.

EXAMPLE:

Designation of a countersink of type A, with a depth, t₁, of 3 mm, for a 4 mm screw thread diameter:

Countersink DIN 74 – A4 × 3

4 Indications on drawings

Indications on drawings shall be as shown in figures 4a to 4d.

EXAMPLE 1: Use of symbols

Figure 4a: Indication of symbols

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EXAMPLE 2: Indication of actual dimensions

Figure 4b: Indication of countersink diameter

Figure 4c: Indication of countersink depth

The connecting component may need to be countersunk.

Figure 4d: Indication for components where s ≤ t₁

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3.9 Content of harmful salts causing efflorescence

Bricks shall be free from harmful salts leading to structural damage in the bricks or plaster. Bricks shall be deemed to have passed the test for harmful salts if the test described in subclause 6.5, carried out on loose bricks, shows that the proportion by mass of magnesium sulfate (MgSO4) does not exceed 0,12 %.

4 Designation

The following symbols shall be used for the various types of brick:

LLz lightweight horizontally perforated brick

LLp lightweight horizontally perforated brick panel

The sequence of elements used when designating lightweight horizontally perforated bricks shall be term, DIN number, type of brick (symbol), compressive strength class, apparent brick density class and format symbol as given in table 6.

Example of designation:

Designation of a lightweight horizontally perforated brick (LLz) of compressive strength class 12, apparent brick density class 0,9, length l = 240 mm, width b = 175 mm and height h = 113 mm (3 DF):

Brick DIN 105 — LLz 12 — 0,9 — 3 DF

The sequence of elements used when designating lightweight horizontally perforated brick panels shall be DIN number, type of brick (symbol), apparent brick density class and format symbol as given in table 7.

Example of designation:

Designation of a lightweight horizontally perforated brick panel (LLp) of apparent brick density class 0,6, length l = 330 mm, height h = 238 mm and thickness s = 80 mm (80 s):

Brick DIN 105 — LLp 0,6 — 80 s

If lightweight horizontally perforated brick panels are produced with differing length or height, these dimensions shall also be stated in the designation.

Example of designation:

Designation of a lightweight horizontally perforated brick panel (LLp) of apparent brick density class 0,6, length l = 495 mm, height h = 320 mm and thickness s = 60 mm:

Brick DIN 105 — LLp 0,6 — 495 × 320 × 60

5 Marking

All bricks shall be provided with a works mark (manufacturer's mark) and the symbol identifying the brick type (LLz or LLp).

Lightweight horizontally perforated bricks ready for dispatch shall additionally be marked on one stretcher face with a colour coding stripe not less than 20 mm in width, indicating the compressive strength class (see table 8) and details of their apparent brick density class.

An indication of the apparent density class is considered adequate for lightweight horizontally perforated brick panels.

It shall be deemed sufficient if one brick is marked for up to 200 lightweight horizontally perforated bricks not less than 10 DF and for up to 50 lightweight horizontally perforated brick panels.

Table 6. Lightweight horizontally perforated bricks, format symbols (examples)

Format symbol DF (thin format)	Dimensions
	l	b	h
NF	240	115	71
2 DF	240	115	113
3 DF	240	175	113
8 DF	240	240	238
12 DF	365	240	238
16 DF	490	240	238
10 DF	240	300	238
15 DF	365	300	238
20 DF	490	300	238

Table 7. Lightweight horizontally perforated brick panels, format symbols (examples)

Format symbols	Dimensions
	l	h	s
40 s	330	238	40
50 s	330	238	50
60 s	330	238	60
70 s	330	238	70
80 s	330	238	80
100 s	330	238	100
115 s	330	238	115

Table 8. Colour coding

Compressive strength class	Colour
2	Green
4	Blue
6	Red
12	No marking

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6 Testing

6.1 Shape, dimensions, perforation

In accordance with DIN 105 Part 1.

A measuring rule or a gauge board with a millimetre scale is sufficient for measuring the length of lightweight horizontally perforated brick panels with dimensions exceeding 495 mm.

The deflection shall also be determined for lightweight horizontally perforated brick panels as illustrated in figure 5. In this determination, the panel shall be pressed on a longitudinal face or width against a smooth surface. Deviations from straightness shall be determined using a measuring wedge and stated to the nearest whole millimetre.

6.2 Apparent brick density

In accordance with DIN 105 Part 1.

6.3 Compressive strength

In accordance with DIN 105 Part 1.

Lightweight horizontally perforated bricks, including standard format bricks, shall be tested as whole bricks. Form factors shall not be applied.

6.4 Bending strength

The bending strength of lightweight horizontally perforated brick panels shall be determined on 5 air-dried samples.

Each panel shall be tested lying flat. The panel shall be placed on two supports so that it can move and stressed in the middle parallel to the supports by means of a 20 mm wide mandrel. The distance between supports shall equal the length of the panel minus 50 mm. The load shall be increased steadily at a rate of approximately 10 N per second.

6.5 Expansive particles and water-soluble salts

In accordance with DIN 105 Part 1.

7 Inspection

7.1 General

See DIN 105 Part 1.

7.2 Internal control

In accordance with DIN 105 Part 1.

7.3 Third party inspection

In accordance with DIN 105 Part 1.

The inspection of lightweight horizontally perforated brick panels shall include the bending strength test instead of the compressive strength test and the determination of deflection.

8 Delivery note

In accordance with DIN 105 Part 1.

Standards referred to

DIN 105 Part 1 Clay bricks; solid bricks and vertically perforated bricks

International Patent Classification

E 04 C 1-00

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