GB1599070A

GB1599070A - Threaded insert particularly for securing to thin sheets

Info

Publication number: GB1599070A
Application number: GB25520/78A
Authority: GB
Original assignee: VYZK USTAV MECH
Current assignee: VYZK USTAV MECH
Priority date: 1977-06-08
Filing date: 1978-05-31
Publication date: 1981-09-30
Also published as: BE867007A; DE2818588C3; PL207397A1; DE2818588A1; DD136171A1; AU3657878A; IT7824272A0; JPS545162A; ES244270U; FR2393972A1; DE2818588B2; CS191362B1; FR2393972B1; CA1100795A; ES244270Y; AT360808B; IT1097805B; PL116611B2; ATA412778A; SE7806695L

Abstract

The blind rivet nut has a hollow shank (1) and an end part (3) with a threaded opening (4). The hollow shank (1), which is adjoined by an insert head (2), has a relatively thin portion (5), with a large internal diameter, and a second portion (7) with a smaller diameter; it is provided with axially extending reinforcements (9) on its outer side. By means of a mounting tool screwed into the threaded opening (4), the blind rivet nut is introduced, with the end bearing the insert head (2), into the metal sheet (14). By axial tension on the tool, the hollow shank (1) is upset and buckles at the transition between the two portions (5, 7) until the portion (5) with larger internal diameter finally rests on the metal sheet (14) and reinforces the latter substantially with respect to tension. <IMAGE>

Description

(54) THREADED INSERT, PARTICULARLY FOR SECURING TO THIN SHEETS (71) We, VUMA, Vyskumny ustav mechanizacie a automatizacie, a Czechoslovak body corporate, of Nove Mesto nad Vahom, Czechoslovakia, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to a threaded insert capable of being fixed to a sheet, particularly a thin sheet, from one side thereof.

Different types of threaded inserts are used for creating nut threads in thin sheets.

The different types have different methods for fixing them in the sheet. There are threaded inserts which, to be fixed, need access from both sides of the sheet and inserts which can be fixed when there is access from one side only. Among threaded inserts fixed from one side only are rivet nuts having a hollow shaft with a threaded part on one end. One sided connection elements which can be fixed in an opening of a sheet from one side only of the type of a "rivet nut" have, however, in addition to known advantages also a number of drawbacks.

Their drawbacks are mainly in their application within a narrow and positively limited range of fixing. It is furthermore known from the technical practice that any connection means serving for connection of thin sheets has in addition to its main purpose, namely the creation of a solid and reliable connection, also the task of reinforcing the thin sheet. Known threaded inserts do not meet this requirement, as the size of the formed insert is substantially the same for thin and for thick sheets.

We have sought to provide a threaded insert which is capable of being fixed from one side only of a sheet and which, particularly for thin sheets, provides a substantial reinforcement of the connection by provision of a closing head with a large diameter on the inaccessible side of the sheet.

According to the invention, there is provided a threaded insert capable of being fixed to a sheet from one side thereof, the insert comprising a thrust head at one end, a terminal part at the other end which is provided with an internal thread and a cylindrical hollow shank between the thrust head and the terminal part, the hollow shank consisting of a first part adjacent the thrust head and a second part merging into the first part and adjacent and merging into the terminal part of the insert, the second part of the hollow shank having a smaller internal diameter and a larger wall thickness than the first part of the hollow shank, and the terminal threaded portion of the insert having a smaller internal diameter and a larger wall thickness than the second part of the shank; the external surface of the insert being provided with an annular groove in the region where the second part of the hollow shank merges into the terminal threaded part of the insert.

The threaded insert of the invention is made in one piece.

Preferably, the external surface of the hollow shank is provided with axial reinforcement which can be formed by a pressing operation. Preferably, the axial reinforcement is in the form of radial depressions in the external surface of the shank wall.

An advantage of the threaded insert according to this invention is that it is par ticularly adapted for use with thin sheets but due to the annular groove in the external side of the insert which permits the two parts of the hollow shank to deform outwardly to assume a configuration of conical annular portions which thrust against the inner surface of the sheet to which the insert is being fixed to form a closing head, the insert can be fixed in sheets of different thickness at a high stress resistance of the closing head. Another advantage is that the closing head is largest for thin sheets where a substantial reinforcement by a supporting plate is required.For thicker sheets, where the same degree of reinforcement by the closing head is not required, the diameter of the closing head is smaller, but has an increased resistivity to stress by pull and torsion.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an elevation, with parts in longitudinal section, of one embodiment of a threaded insert according to the invention; Figure 2 is a cross-section thereof taken along the line A-A of Figure 1; Figure 3 shows in elevation another embodiment of a threaded insert according to the invention; Figure 4 is a cross section thereof taken along the line B-B of Figure 3; Figure 5 shows in elevation a further insert according to the invention; Figure 6 shows a cross section thereof taken along the line C-C of FigureS; Figure 7 is a section through the insert shown in Figure 1 shown placed in an opening in a sheet; Figure 8 is an elevation showing an intermediate stage in the attaching to the insert to the sheet shown in Figure 7;; Figure 9 is a part-section, part-elevation showing the insert finally attached to the sheet; and Figure 10 is a similar view to Figure 9 showing the finally attached insert fixed to a thick sheet.

The threaded insert 1 shown in Figures 1 and 2 is capable of being attached to a sheet, and particularly a thin sheet from one side.

It comprises a hollow shank terminated at one end by a thrust head 2 and at the other end 3 with an internal threaded terminal part 4. The hollow shank of the insert has a larger internal diameter 5 near the head, a smaller internal diameter 7 at an intermediate position and has a narrower internal diameter in the region of the threaded part 4.

Over the region of the larger internal diameter 5, the insert 1 has a small wall thickness while over one third of its length over the region of the smaller internal diameter 7 has a larger wall thickness. The diameter of the internal diameter 7 is somewhat larger than the diameter of the threaded part 4 in allowing the threaded mandrel of an assembly tool to be screwed into the threaded part 4.

The external surface of the insert 1 can be circular. However it is advantageous to provide at least over the regions of the diameters 5 and 7, axial reinforcements 9 which may have been formed by pressing 8 to the cross-sectional shape shown in Figure 2.

According to alternative embodiments of inserts, these axial reinforcements can be in the form shown in Figures 3 and 4, or the overall section of the insert can be given the shape shown in Figures 5 and 6. An annular groove 12 is provided in the external surface of the insert at a position where the smaller diameter 7 merges into the threaded part 4.

The depth of this groove 12 is about half the thickness of the wall in the region of the smaller diameter 7.

The fixing of the insert into an opening 13 in a thin sheet 14 is shown in Figures 7, 8 and 9. The threaded insert is screwed onto the threaded mandrel 10 of an assembly tool until the thrust head 2 of the insert strikes an abutment 11 on the assembly tool. As the mandrel 10 continues to be screwed into the insert, a sudden deformation takes place in the transition part between the smaller diameter 7 and the larger diameter 5 whereby the shaped part 1 of the insert starts to extend radially and takes a shape similar to two concave washers facing one another with their largest diameters adjacent one another.In the course of a further approach of the threaded part 4, the part of the shank coinciding with the larger diameter 5 bears on the inaccessible side of the thin sheet 14 and the part of the shank with the smaller diameter 7 maintains its obtained shape of a concave washer which starts to bear on the portion of larger diameter 5 until the shape shown in Figure 9 is achieved. The diameter of the shaped closing head in a thin sheet 14 is in comparison to classical rivet nuts substantial larger with the consequence of a substantial increase of stress resistance to pull to the removal of the insert from the sheet.

The insert of the invention can be fixed to thicker sheets such as the sheet 15 shown in Figure 10 and is the same as the fixing of the insert into a thin sheet 14. There is a difference however in the diameter of the closing head of the connection formed, which diameter is smaller, whereby the formed closing head of the insert has a high resistivity to stresses of the thread connection when pulled. By comparing Figures 9 and 10, the wide range of application of the threaded insert is obvious.

WHAT WE CLAIM IS: 1. A threaded insert capable of being fixed to a sheet from one side thereof, the insert comprising a thrust head at one end, a terminal part at the other end which is provided with an internal thread and a cylindrical hollow shank between the thrust head and the terminal part, the hollow shank consisting of a first part adjacent the thrust head and a second part merging into the first part and adjacent and merging into the terminal part of the insert, the second part of the hollow shank having a smaller internal diameter and a larger wall thickness than the first part of the hollow shank, and the terminal threaded portion of the insert having a smaller internal diameter and a larger wall thickness than the second part of the shank; the external surface of the insert being provided with an annular groove in the region where the second part of the hollow shank merges into the terminal

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. way of example, with reference to the accompanying drawings, in which: Figure 1 is an elevation, with parts in longitudinal section, of one embodiment of a threaded insert according to the invention; Figure 2 is a cross-section thereof taken along the line A-A of Figure 1; Figure 3 shows in elevation another embodiment of a threaded insert according to the invention; Figure 4 is a cross section thereof taken along the line B-B of Figure 3; Figure 5 shows in elevation a further insert according to the invention; Figure 6 shows a cross section thereof taken along the line C-C of FigureS; Figure 7 is a section through the insert shown in Figure 1 shown placed in an opening in a sheet;; Figure 8 is an elevation showing an intermediate stage in the attaching to the insert to the sheet shown in Figure 7; Figure 9 is a part-section, part-elevation showing the insert finally attached to the sheet; and Figure 10 is a similar view to Figure 9 showing the finally attached insert fixed to a thick sheet. The threaded insert 1 shown in Figures 1 and 2 is capable of being attached to a sheet, and particularly a thin sheet from one side. It comprises a hollow shank terminated at one end by a thrust head 2 and at the other end 3 with an internal threaded terminal part 4. The hollow shank of the insert has a larger internal diameter 5 near the head, a smaller internal diameter 7 at an intermediate position and has a narrower internal diameter in the region of the threaded part 4. Over the region of the larger internal diameter 5, the insert 1 has a small wall thickness while over one third of its length over the region of the smaller internal diameter 7 has a larger wall thickness. The diameter of the internal diameter 7 is somewhat larger than the diameter of the threaded part 4 in allowing the threaded mandrel of an assembly tool to be screwed into the threaded part 4. The external surface of the insert 1 can be circular. However it is advantageous to provide at least over the regions of the diameters 5 and 7, axial reinforcements 9 which may have been formed by pressing 8 to the cross-sectional shape shown in Figure 2. According to alternative embodiments of inserts, these axial reinforcements can be in the form shown in Figures 3 and 4, or the overall section of the insert can be given the shape shown in Figures 5 and 6. An annular groove 12 is provided in the external surface of the insert at a position where the smaller diameter 7 merges into the threaded part 4. The depth of this groove 12 is about half the thickness of the wall in the region of the smaller diameter 7. The fixing of the insert into an opening 13 in a thin sheet 14 is shown in Figures 7, 8 and 9. The threaded insert is screwed onto the threaded mandrel 10 of an assembly tool until the thrust head 2 of the insert strikes an abutment 11 on the assembly tool. As the mandrel 10 continues to be screwed into the insert, a sudden deformation takes place in the transition part between the smaller diameter 7 and the larger diameter 5 whereby the shaped part 1 of the insert starts to extend radially and takes a shape similar to two concave washers facing one another with their largest diameters adjacent one another.In the course of a further approach of the threaded part 4, the part of the shank coinciding with the larger diameter 5 bears on the inaccessible side of the thin sheet 14 and the part of the shank with the smaller diameter 7 maintains its obtained shape of a concave washer which starts to bear on the portion of larger diameter 5 until the shape shown in Figure 9 is achieved. The diameter of the shaped closing head in a thin sheet 14 is in comparison to classical rivet nuts substantial larger with the consequence of a substantial increase of stress resistance to pull to the removal of the insert from the sheet. The insert of the invention can be fixed to thicker sheets such as the sheet 15 shown in Figure 10 and is the same as the fixing of the insert into a thin sheet 14. There is a difference however in the diameter of the closing head of the connection formed, which diameter is smaller, whereby the formed closing head of the insert has a high resistivity to stresses of the thread connection when pulled. By comparing Figures 9 and 10, the wide range of application of the threaded insert is obvious. WHAT WE CLAIM IS:

1. A threaded insert capable of being fixed to a sheet from one side thereof, the insert comprising a thrust head at one end, a terminal part at the other end which is provided with an internal thread and a cylindrical hollow shank between the thrust head and the terminal part, the hollow shank consisting of a first part adjacent the thrust head and a second part merging into the first part and adjacent and merging into the terminal part of the insert, the second part of the hollow shank having a smaller internal diameter and a larger wall thickness than the first part of the hollow shank, and the terminal threaded portion of the insert having a smaller internal diameter and a larger wall thickness than the second part of the shank; the external surface of the insert being provided with an annular groove in the region where the second part of the hollow shank merges into the terminal

threaded part of the insert.

2. A threaded insert as claimed in Claim 1, wherein the external surface of the hollow shank is provided with axial reinforcement.

3. A threaded insert as claimed in Claim 2, wherein the axial reinforcement is in the form of radial depressions in the external surface of the shank wall.

4. A threaded insert as claimed in any of claims 1 to 4, wherein the annular groove is triangular in cross-section.

5. A threaded insert capable of being fixed to a sheet from one side thereof substantially as herein described with reference to Figures 1 and 2, Figures 3 and 4 or Figures 5 and 6 of the accompanying drawings.