Force sensor for manually operated or pneumatic presses

Patent metadata

Field	Value
Publication number	US-2016334287-A1
Application number	US-201415105670-A
Country	US
Kind code	A1
Filing date	Dec 15, 2014
Priority date	Dec 20, 2013
Publication date	Nov 17, 2016
Grant date	—

Abstract

A force sensor for measuring axially occurring forces in manually operated or pneumatic presses has a central axis and an outer diameter and includes a bolt and a nut that preload between them a piezoelectric force washer with a plug connection. The washer has an inner end face defining a first bore having a first diameter with an internal thread. The bolt defines a throughbore with an internal diameter, a head portion and a hollow shaft defining a frontal external thread extending through the force washer and engaging the nut's internal thread. The nut or the head portion defines a second bore with a second diameter measuring smaller than the shafts internal diameter but at least one quarter of the outer diameter and at least as long as its diameter. The inner wall of the second bore defines a center mount for a sliding fit.

First claim

1 - 12 . (canceled)

13 . A force sensor ( 1 ) for measuring axially occurring forces in manually operated or pneumatic presses, the force sensor comprising:
a bolt ( 3 ) that defines a central axis (A) extending axially through the bolt, the bolt defines a head ( 11 ) portion that defines an upper annular surface ( 10 ′) that is normal to the central axis, the head portion defines a lower end face that is normal to the central axis and disposed opposite the upper annular surface, the bolt defines a preloading shaft connected to the head portion opposite the upper annular surface and extending axially from the lower end face of the head portion, the preloading shaft defines a frontal external thread ( 13 ) that is disposed on the end of the preloading shaft that is opposite the end connected to the head portion, the bolt defines a throughbore extending axially through the head portion and the preloading shaft and surrounding the central axis and defining an inner diameter (D I ); a nut ( 4 ) defines an inner end face ( 7 ) that is normal to the central axis, the nut ( 4 ) defines a first bore ( 8 ) that extends axially part way through the nut from the inner end face and surrounding the central axis and having a first diameter (D 1 ) with a first internal thread engaging the frontal external thread ( 13 ) of the preloading shaft, the nut ( 4 ) defines a bearing surface ( 10 ) disposed opposite the inner end face ( 7 ), the nut ( 4 ) defines an axially extending inner wall that defines a second bore ( 14 ) extending axially part way through the nut from the bearing surface ( 10 ) to the first bore and surrounding the central axis and having a second diameter (D 2 ), wherein the second diameter (D 2 ) is smaller than the inner diameter (D I ) of the hollow preloading bolt, wherein the axial length (L) of the second bore is at least as long as the second diameter (D 2 ), and wherein the inner wall of the second bore ( 14 ) is formed as a center mount for a sliding fit; and a piezoelectric force washer ( 5 ) defines a third bore extending axially through the piezoelectric force washer ( 6 ) about the central axis, the piezoelectric force washer ( 5 ) defines a lower annular bearing surface and an upper annular bearing surface disposed spaced apart from the lower annular bearing surface ( 10 , 10 ′), each of the lower annular bearing surface and the upper annular bearing surface is disposed normal to the central axis and defines an outer diameter D A , the piezoelectric force washer ( 5 ) defines a plug connection that is preloaded between the upper annular bearing surface and the lower annular bearing surface, wherein the second diameter (D 2 ) of the second bore is at least one quarter of the outer diameter (D A ) of the piezoelectric force washer ( 5 ), and wherein the preloading shaft extends axially through the third bore to allow the first internal thread of the nut to engage the frontal external thread of the preloading shaft

14 . The force sensor according to claim 13 , wherein:
the nut defines an outer wall that extends axially between the inner end face and the bearing surface, the nut defines a radial bore extending from the outer wall through the inner wall in a central region of the second bore, and the radial bore defines an internal thread that is configured to receive therein a set screw.

15 . The force sensor according to claim 14 , further comprising a set screw threaded into the radial bore.

16 . The force sensor according to claim 13 , wherein an interior thread is defined in the portion of the throughbore extending from the upper bearing surface of the head portion and at least part way towards the preloading shaft.

17 . The force sensor according to claim 16 , wherein:
the nut defines an outer wall that extends axially between the inner end face and the bearing surface, the nut defines a radial bore extending from the outer wall through the inner wall in a central region of the second bore, and the radial bore defines an internal thread that is configured to receive therein a set screw.

18 . The force sensor according to claim 17 , further comprising a set screw threaded into the radial bore.

19 . The force sensor according to claim 1 , wherein the bolt, the nut and the piezoelectric force washer ( 5 ) are configured and disposed to withstand pressure forces up to 60 kN.

20 . The force sensor according to claim 1 , wherein the bolt, the nut and the piezoelectric force washer ( 5 ) are configured and disposed to withstand tensile forces up to 12 kN.

21 . A force sensor ( 1 ) for measuring axially occurring forces in manually operated or pneumatic presses, the force sensor comprising:
a bolt ( 3 ) that defines a central axis (A) extending axially through the bolt, the bolt defines an outer diameter D A disposed radially from the central axis, the bolt defines an upper annular surface ( 10 ) that is normal to the central axis, the bolt includes a head portion that defines a lower end face spaced axially from the upper annular surface ( 10 ); a nut ( 4 ) that defines an inner end face disposed facing the lower end face of the bolt, the nut defines a first bore having a first diameter (D 1 ) with an internal thread, the nut defines a lower annular bearing surface ( 10 ′); and a piezoelectric force washer ( 5 ) preloaded between the bolt and the nut and including a plug connector ( 6 ), the piezoelectric force washer defining an opening extending axially through the piezoelectric force washer; and wherein the bolt has a preloading shaft that defines a frontal external thread extending axially through the opening of the piezoelectric force washer and engaging the internal thread of the nut, wherein the head of the bolt includes an axially extending inner wall that defines a second bore with a second diameter (D 2 ) and that extends axially through the bolt from at least the upper annular surface ( 10 ) toward the lower end face over a length (L) that is at least equal to the diameter (D 2 ) of the second bore, the diameter (D 2 ) of the second bore being at least one quarter of the outer diameter (D A ) of the bolt, and wherein the inner wall of the second bore is formed as a center mount for a sliding fit.

22 . The force sensor according to claim 21 , wherein the nut in the first bore near the end face also has an inner surface formed as a center mount for a sliding fit, and that the bolt adjacent to the external thread facing the head portion has a guiding region that is at least as wide as the external thread and is accommodated in a centered manner in the proximity of the inner end face into the center mount of the first bore.

23 . The force sensor according to claim 21 , further comprising a sliding disk disposed between the piezoelectric force washer and the head portion of the bolt and fixed by the preload between the bolt and the nut.

24 . The force sensor according to claim 21 wherein the first bore defines the internal thread of the nut and extends axially part way through the nut from the inner end face toward the lower annular bearing surface.

25 . The force sensor according to claim 24 , wherein:
the head defines an outer wall that extends axially between the lower end face and the upper annular surface, the head defines a radial bore extending radially from the outer wall through the inner wall in a central region of the second bore, and the radial bore defines an internal thread that is configured to receive therein a set screw.

26 . The force sensor according to claim 25 , further comprising a set screw threaded into the radial bore.

27 . The forc

Assignees

• Kistler Holding Ag

Inventors

• Lehmann Andri Michael

Classifications

• G01L1/16 Primary

  using properties of piezoelectric devices · CPC title

• G01L5/0038

  applying a pushing force · CPC title

• G01L5/0076

  Force sensors associated with manufacturing machines (G01L5/0066, G01L5/0071 and B23Q17/09 take precedence; for the specific machine or operation involved see relevant class, e.g. B21 - B42) · CPC title

• B30B15/0094

  Press load monitoring means (B30B15/281 takes precedence) · CPC title